virtio-fs cache preventing host file updates in VM

[awprice]

Description of problem

Part of our workload that we run in Kata containers involves watching the logs from the Kata container on the host side from within the Kata VM. We do this by mounting the log files using a hostPath volume in Kubernetes.

Our process then opens the file, then continuously uses the read syscall to get each line of the file.

This worked fine when we used 9p for sharing, but since switching to virtio-fs it doesn't work properly.

When using virtio-fs with virtio_fs_cache set to either auto or always, our process isn't able to read the new lines added to the log file. Switching virtio_fs_cache to none works, but we've experienced other commands failing, e.g. apt-get update. Switching to none isn't really ideal as we like the performance benefits of auto/always.

Replication steps

The following pod spec can be used to replicate:

apiVersion: v1
kind: Pod
metadata:
  name: test
  namespace: default
  annotations:
    io.kubernetes.cri.untrusted-workload: "true"
spec:
  containers:
    - name: sleep
      image: ubuntu
      command: [ "/bin/sh", "-c", "--" ]
      args: [ "while true; do date; sleep 1; done;" ]
    - name: tail
      image: golang:1.12
      command:
        - sleep
        - "3600"
      volumeMounts:
        - mountPath: /containers
          name: container-logs
          readOnly: true
          subPath: $(POD_ID)
      env:
        - name: POD_ID
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.uid
  volumes:
    - hostPath:
        path: /var/log/pods
        type: ""
      name: container-logs

Once the pod has started, exec into the tail container, and run the go script:

$ kubectl exec -it -c tail test bash
# Install a text editor
$ apt update && apt install -y vim
# Create the script, paste in code from below
$ vim /go-log.go
# Run the go script
$ go run /go-log.go /containers/sleep/0.log 

The following go script can be used:

package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
)

func main() {
	if len(os.Args) < 2 {
		panic("Provide path to log file")
	}

	file, err := os.Open(os.Args[1])
	if err != nil {
		panic(err)
	}

	r := bufio.NewReader(file)
	for {
		line, _, err := r.ReadLine()
		if err != nil {
			if err == io.EOF {
				continue
			}
			panic(err)
		}
		fmt.Println(string(line))
	}
}

Expected result

When following the above steps in Replication steps, the expected result is for the current contents of the log file to be printed, but also for the script to continue tailing the file.

See the behaviour of tail -f /containers/sleep/0.log for how the script should work.

Actual result

When following the above steps in Replication steps, what happens is the current contents of the log file to be printed, but any subsequent log lines are not printed.

When we run tail -f /containers/sleep/0.log on the log file, we can see the new log lines are printed as expected.

I believe this is because the tail command uses the fstat syscall on the file between read syscalls, whereas our script continuously runs the read syscall on the fd.

I think this might also be related to #1505

Show kata-collect-data.sh details

Meta details

Running kata-collect-data.sh version 1.8.0 (commit 31b8cb3fbc7b1de9c94201aed7c54ddb73e97587) at 2019-07-22.03:15:38.774601076+0000.

---

Runtime is /opt/kata/bin/kata-runtime.

kata-env

Output of "/opt/kata/bin/kata-runtime kata-env":

[Meta]
  Version = "1.0.23"

[Runtime]
  Debug = false
  Trace = false
  DisableGuestSeccomp = true
  DisableNewNetNs = false
  Path = "/opt/kata/bin/kata-runtime"
  [Runtime.Version]
    Semver = "1.8.0"
    Commit = "31b8cb3fbc7b1de9c94201aed7c54ddb73e97587"
    OCI = "1.0.1-dev"
  [Runtime.Config]
    Path = "/etc/kata-containers/configuration.toml"

[Hypervisor]
  MachineType = "virt"
  Version = "NEMU (like QEMU) version 4.0.0 (kata-static)\nCopyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers"
  Path = "/opt/kata/bin/nemu-system-x86_64"
  BlockDeviceDriver = "virtio-scsi"
  EntropySource = "/dev/urandom"
  Msize9p = 8192
  MemorySlots = 10
  Debug = false
  UseVSock = false
  SharedFS = "virtio-fs"

[Image]
  Path = "/opt/kata/share/kata-containers/kata-containers-ubuntu-console-1.8.0-9e0a061.img"

[Kernel]
  Path = "/opt/kata/share/kata-containers/vmlinuz-4.19.52-45"
  Parameters = "init=/usr/lib/systemd/systemd systemd.unit=kata-containers.target systemd.mask=systemd-networkd.service systemd.mask=systemd-networkd.socket"

[Initrd]
  Path = ""

[Proxy]
  Type = "kataProxy"
  Version = "kata-proxy version 1.8.0-7cd620094df16486c19b2c20300f9847a94c23af"
  Path = "/opt/kata/libexec/kata-containers/kata-proxy"
  Debug = false

[Shim]
  Type = "kataShim"
  Version = "kata-shim version 1.8.0-bc65ea8385a09611054d95b5dbc8f858f87c3d7a"
  Path = "/opt/kata/libexec/kata-containers/kata-shim"
  Debug = false

[Agent]
  Type = "kata"
  Debug = false
  Trace = false
  TraceMode = ""
  TraceType = ""

[Host]
  Kernel = "4.19.50-coreos-r1"
  Architecture = "amd64"
  VMContainerCapable = true
  SupportVSocks = true
  [Host.Distro]
    Name = "Container Linux by CoreOS"
    Version = "2135.4.0"
  [Host.CPU]
    Vendor = "GenuineIntel"
    Model = "Intel(R) Xeon(R) CPU E5-2686 v4 @ 2.30GHz"

[Netmon]
  Version = "kata-netmon version 1.8.0"
  Path = "/opt/kata/libexec/kata-containers/kata-netmon"
  Debug = false
  Enable = false

---

Runtime config files

Runtime default config files

/etc/kata-containers/configuration.toml
/opt/kata/share/defaults/kata-containers/configuration.toml

Runtime config file contents

Output of "cat "/etc/kata-containers/configuration.toml"":

# Copyright (c) 2019 Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0
#

# XXX: WARNING: this file is auto-generated.
# XXX:
# XXX: Source file: "cli/config/configuration-nemu.toml.in"
# XXX: Project:
# XXX:   Name: Kata Containers
# XXX:   Type: kata

# nemu utilizes the 'qemu' hypervisor template type, since it closely matches qemu
[hypervisor.qemu]
path = "/opt/kata/bin/nemu-system-x86_64"
kernel = "/opt/kata/share/kata-containers/vmlinuz.container"
image = "/opt/kata/share/kata-containers/kata-containers.img"
machine_type = "virt"

# Optional space-separated list of options to pass to the guest kernel.
# For example, use `kernel_params = "vsyscall=emulate"` if you are having
# trouble running pre-2.15 glibc.
#
# WARNING: - any parameter specified here will take priority over the default
# parameter value of the same name used to start the virtual machine.
# Do not set values here unless you understand the impact of doing so as you
# may stop the virtual machine from booting.
# To see the list of default parameters, enable hypervisor debug, create a
# container and look for 'default-kernel-parameters' log entries.
kernel_params = ""

# Path to the firmware.
# If you want that qemu uses the default firmware leave this option empty
firmware = "/opt/kata/share/kata-nemu/OVMF.fd"

# Machine accelerators
# comma-separated list of machine accelerators to pass to the hypervisor.
# For example, `machine_accelerators = "nosmm,nosmbus,nosata,nopit,static-prt,nofw"`
machine_accelerators=""

# Default number of vCPUs per SB/VM:
# unspecified or 0                --> will be set to 1
# < 0                             --> will be set to the actual number of physical cores
# > 0 <= number of physical cores --> will be set to the specified number
# > number of physical cores      --> will be set to the actual number of physical cores
default_vcpus = 1

# Default maximum number of vCPUs per SB/VM:
# unspecified or == 0             --> will be set to the actual number of physical cores or to the maximum number
#                                     of vCPUs supported by KVM if that number is exceeded
# > 0 <= number of physical cores --> will be set to the specified number
# > number of physical cores      --> will be set to the actual number of physical cores or to the maximum number
#                                     of vCPUs supported by KVM if that number is exceeded
# WARNING: Depending of the architecture, the maximum number of vCPUs supported by KVM is used when
# the actual number of physical cores is greater than it.
# WARNING: Be aware that this value impacts the virtual machine's memory footprint and CPU
# the hotplug functionality. For example, `default_maxvcpus = 240` specifies that until 240 vCPUs
# can be added to a SB/VM, but the memory footprint will be big. Another example, with
# `default_maxvcpus = 8` the memory footprint will be small, but 8 will be the maximum number of
# vCPUs supported by the SB/VM. In general, we recommend that you do not edit this variable,
# unless you know what are you doing.
default_maxvcpus = 0

# Bridges can be used to hot plug devices.
# Limitations:
# * Currently only pci bridges are supported
# * Until 30 devices per bridge can be hot plugged.
# * Until 5 PCI bridges can be cold plugged per VM.
#   This limitation could be a bug in the kernel
# Default number of bridges per SB/VM:
# unspecified or 0   --> will be set to 1
# > 1 <= 5           --> will be set to the specified number
# > 5                --> will be set to 5
default_bridges = 1

# Default memory size in MiB for SB/VM.
# If unspecified then it will be set 2048 MiB.
default_memory = 2048
#
# Default memory slots per SB/VM.
# If unspecified then it will be set 10.
# This is will determine the times that memory will be hotadded to sandbox/VM.
#memory_slots = 10

# The size in MiB will be plused to max memory of hypervisor.
# It is the memory address space for the NVDIMM devie.
# If set block storage driver (block_device_driver) to "nvdimm",
# should set memory_offset to the size of block device.
# Default 0
#memory_offset = 0

# Disable block device from being used for a container's rootfs.
# In case of a storage driver like devicemapper where a container's 
# root file system is backed by a block device, the block device is passed
# directly to the hypervisor for performance reasons. 
# This flag prevents the block device from being passed to the hypervisor, 
# 9pfs is used instead to pass the rootfs.
disable_block_device_use = false

# Shared file system type:
#   - virtio-fs (default)
#   - virtio-9p
shared_fs = "virtio-fs"

# Path to vhost-user-fs daemon.
virtio_fs_daemon = "/opt/kata/bin/virtiofsd-x86_64"

# Default size of DAX cache in MiB
virtio_fs_cache_size = 1024

# Cache mode:
#
#  - none
#    Metadata, data, and pathname lookup are not cached in guest. They are
#    always fetched from host and any changes are immediately pushed to host.
#
#  - auto
#    Metadata and pathname lookup cache expires after a configured amount of
#    time (default is 1 second). Data is cached while the file is open (close
#    to open consistency).
#
#  - always
#    Metadata, data, and pathname lookup are cached in guest and never expire.
virtio_fs_cache = "auto"

# Block storage driver to be used for the hypervisor in case the container
# rootfs is backed by a block device. This is virtio-scsi, virtio-blk
# or nvdimm.
block_device_driver = "virtio-scsi"

# Specifies cache-related options will be set to block devices or not.
# Default false
#block_device_cache_set = true

# Specifies cache-related options for block devices.
# Denotes whether use of O_DIRECT (bypass the host page cache) is enabled.
# Default false
#block_device_cache_direct = true

# Specifies cache-related options for block devices.
# Denotes whether flush requests for the device are ignored.
# Default false
#block_device_cache_noflush = true

# Enable iothreads (data-plane) to be used. This causes IO to be
# handled in a separate IO thread. This is currently only implemented
# for SCSI.
#
enable_iothreads = false

# Enable pre allocation of VM RAM, default false
# Enabling this will result in lower container density
# as all of the memory will be allocated and locked
# This is useful when you want to reserve all the memory
# upfront or in the cases where you want memory latencies
# to be very predictable
# Default false
#enable_mem_prealloc = true

# Enable huge pages for VM RAM, default false
# Enabling this will result in the VM memory
# being allocated using huge pages.
# This is useful when you want to use vhost-user network
# stacks within the container. This will automatically 
# result in memory pre allocation
enable_hugepages = false

# Enable swap of vm memory. Default false.
# The behaviour is undefined if mem_prealloc is also set to true
#enable_swap = true

# This option changes the default hypervisor and kernel parameters
# to enable debug output where available. This extra output is added
# to the proxy logs, but only when proxy debug is also enabled.
# 
# Default false
#enable_debug = true

# Disable the customizations done in the runtime when it detects
# that it is running on top a VMM. This will result in the runtime
# behaving as it would when running on bare metal.
# 
#disable_nesting_checks = true

# This is the msize used for 9p shares. It is the number of bytes 
# used for 9p packet payload.
#msize_9p = 8192

# If true and vsocks are supported, use vsocks to communicate directly
# with the agent (no proxy is started).
# Default true
#use_vsock = true

# VFIO devices are hotplugged on a bridge by default. 
# Enable hotplugging on root bus. This may be required for devices with
# a large PCI bar, as this is a current limitation with hotplugging on 
# a bridge. This value is valid for "pc" machine type.
# Default false
#hotplug_vfio_on_root_bus = true

# If host doesn't support vhost_net, set to true. Thus we won't create vhost fds for nics.
# Default false
#disable_vhost_net = true
#
# Default entropy source.
# The path to a host source of entropy (including a real hardware RNG)
# /dev/urandom and /dev/random are two main options.
# Be aware that /dev/random is a blocking source of entropy.  If the host
# runs out of entropy, the VMs boot time will increase leading to get startup
# timeouts.
# The source of entropy /dev/urandom is non-blocking and provides a
# generally acceptable source of entropy. It should work well for pretty much
# all practical purposes.
#entropy_source= "/dev/urandom"

# Path to OCI hook binaries in the *guest rootfs*.
# This does not affect host-side hooks which must instead be added to
# the OCI spec passed to the runtime.
#
# You can create a rootfs with hooks by customizing the osbuilder scripts:
# https://github.com/kata-containers/osbuilder
#
# Hooks must be stored in a subdirectory of guest_hook_path according to their
# hook type, i.e. "guest_hook_path/{prestart,postart,poststop}".
# The agent will scan these directories for executable files and add them, in
# lexicographical order, to the lifecycle of the guest container.
# Hooks are executed in the runtime namespace of the guest. See the official documentation:
# https://github.com/opencontainers/runtime-spec/blob/v1.0.1/config.md#posix-platform-hooks
# Warnings will be logged if any error is encountered will scanning for hooks,
# but it will not abort container execution.
#guest_hook_path = "/usr/share/oci/hooks"

[factory]
# VM templating support. Once enabled, new VMs are created from template
# using vm cloning. They will share the same initial kernel, initramfs and
# agent memory by mapping it readonly. It helps speeding up new container
# creation and saves a lot of memory if there are many kata containers running
# on the same host.
#
# When disabled, new VMs are created from scratch.
#
# Note: Requires "initrd=" to be set ("image=" is not supported).
#
# Default false
#enable_template = true

# Specifies the path of template.
#
# Default "/run/vc/vm/template"
#template_path = "/run/vc/vm/template"

# The number of caches of VMCache:
# unspecified or == 0   --> VMCache is disabled
# > 0                   --> will be set to the specified number
#
# VMCache is a function that creates VMs as caches before using it.
# It helps speed up new container creation.
# The function consists of a server and some clients communicating
# through Unix socket.  The protocol is gRPC in protocols/cache/cache.proto.
# The VMCache server will create some VMs and cache them by factory cache.
# It will convert the VM to gRPC format and transport it when gets
# requestion from clients.
# Factory grpccache is the VMCache client.  It will request gRPC format
# VM and convert it back to a VM.  If VMCache function is enabled,
# kata-runtime will request VM from factory grpccache when it creates
# a new sandbox.
#
# Default 0
#vm_cache_number = 0

# Specify the address of the Unix socket that is used by VMCache.
#
# Default /var/run/kata-containers/cache.sock
#vm_cache_endpoint = "/var/run/kata-containers/cache.sock"

[proxy.kata]
path = "/opt/kata/libexec/kata-containers/kata-proxy"

# If enabled, proxy messages will be sent to the system log
# (default: disabled)
#enable_debug = true

[shim.kata]
path = "/opt/kata/libexec/kata-containers/kata-shim"

# If enabled, shim messages will be sent to the system log
# (default: disabled)
#enable_debug = true

# If enabled, the shim will create opentracing.io traces and spans.
# (See https://www.jaegertracing.io/docs/getting-started).
#
# Note: By default, the shim runs in a separate network namespace. Therefore,
# to allow it to send trace details to the Jaeger agent running on the host,
# it is necessary to set 'disable_new_netns=true' so that it runs in the host
# network namespace.
#
# (default: disabled)
#enable_tracing = true

[agent.kata]
# If enabled, make the agent display debug-level messages.
# (default: disabled)
#enable_debug = true

# Enable agent tracing.
#
# If enabled, the default trace mode is "dynamic" and the
# default trace type is "isolated". The trace mode and type are set
# explicity with the `trace_type=` and `trace_mode=` options.
#
# Notes:
#
# - Tracing is ONLY enabled when `enable_tracing` is set: explicitly
#   setting `trace_mode=` and/or `trace_type=` without setting `enable_tracing`
#   will NOT activate agent tracing.
#
# - See https://github.com/kata-containers/agent/blob/master/TRACING.md for
#   full details.
#
# (default: disabled)
#enable_tracing = true
#
#trace_mode = "dynamic"
#trace_type = "isolated"

[netmon]
# If enabled, the network monitoring process gets started when the
# sandbox is created. This allows for the detection of some additional
# network being added to the existing network namespace, after the
# sandbox has been created.
# (default: disabled)
#enable_netmon = true

# Specify the path to the netmon binary.
path = "/opt/kata/libexec/kata-containers/kata-netmon"

# If enabled, netmon messages will be sent to the system log
# (default: disabled)
#enable_debug = true

[runtime]
# If enabled, the runtime will log additional debug messages to the
# system log
# (default: disabled)
#enable_debug = true
#
# Internetworking model
# Determines how the VM should be connected to the
# the container network interface
# Options:
#
#   - bridged
#     Uses a linux bridge to interconnect the container interface to
#     the VM. Works for most cases except macvlan and ipvlan.
#
#   - macvtap
#     Used when the Container network interface can be bridged using
#     macvtap.
#
#   - none
#     Used when customize network. Only creates a tap device. No veth pair.
#
#   - tcfilter
#     Uses tc filter rules to redirect traffic from the network interface
#     provided by plugin to a tap interface connected to the VM.
#
internetworking_model="tcfilter"

# disable guest seccomp
# Determines whether container seccomp profiles are passed to the virtual
# machine and applied by the kata agent. If set to true, seccomp is not applied
# within the guest
# (default: true)
disable_guest_seccomp=true

# If enabled, the runtime will create opentracing.io traces and spans.
# (See https://www.jaegertracing.io/docs/getting-started).
# (default: disabled)
#enable_tracing = true

# If enabled, the runtime will not create a network namespace for shim and hypervisor processes.
# This option may have some potential impacts to your host. It should only be used when you know what you're doing.
# `disable_new_netns` conflicts with `enable_netmon`
# `disable_new_netns` conflicts with `internetworking_model=bridged` and `internetworking_model=macvtap`. It works only
# with `internetworking_model=none`. The tap device will be in the host network namespace and can connect to a bridge
# (like OVS) directly.
# If you are using docker, `disable_new_netns` only works with `docker run --net=none`
# (default: false)
#disable_new_netns = true

# Enabled experimental feature list, format: ["a", "b"].
# Experimental features are features not stable enough for production,
# They may break compatibility, and are prepared for a big version bump.
# Supported experimental features:
# 1. "newstore": new persist storage driver which breaks backward compatibility,
#				expected to move out of experimental in 2.0.0.
# (default: [])
experimental=[]

Output of "cat "/opt/kata/share/defaults/kata-containers/configuration.toml"":

# Copyright (c) 2017-2019 Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0
#

# XXX: WARNING: this file is auto-generated.
# XXX:
# XXX: Source file: "cli/config/configuration-qemu.toml.in"
# XXX: Project:
# XXX:   Name: Kata Containers
# XXX:   Type: kata

[hypervisor.qemu]
path = "/opt/kata/bin/qemu-system-x86_64"
kernel = "/opt/kata/share/kata-containers/vmlinuz.container"
image = "/opt/kata/share/kata-containers/kata-containers.img"
machine_type = "pc"

# Optional space-separated list of options to pass to the guest kernel.
# For example, use `kernel_params = "vsyscall=emulate"` if you are having
# trouble running pre-2.15 glibc.
#
# WARNING: - any parameter specified here will take priority over the default
# parameter value of the same name used to start the virtual machine.
# Do not set values here unless you understand the impact of doing so as you
# may stop the virtual machine from booting.
# To see the list of default parameters, enable hypervisor debug, create a
# container and look for 'default-kernel-parameters' log entries.
kernel_params = ""

# Path to the firmware.
# If you want that qemu uses the default firmware leave this option empty
firmware = ""

# Machine accelerators
# comma-separated list of machine accelerators to pass to the hypervisor.
# For example, `machine_accelerators = "nosmm,nosmbus,nosata,nopit,static-prt,nofw"`
machine_accelerators=""

# Default number of vCPUs per SB/VM:
# unspecified or 0                --> will be set to 1
# < 0                             --> will be set to the actual number of physical cores
# > 0 <= number of physical cores --> will be set to the specified number
# > number of physical cores      --> will be set to the actual number of physical cores
default_vcpus = 1

# Default maximum number of vCPUs per SB/VM:
# unspecified or == 0             --> will be set to the actual number of physical cores or to the maximum number
#                                     of vCPUs supported by KVM if that number is exceeded
# > 0 <= number of physical cores --> will be set to the specified number
# > number of physical cores      --> will be set to the actual number of physical cores or to the maximum number
#                                     of vCPUs supported by KVM if that number is exceeded
# WARNING: Depending of the architecture, the maximum number of vCPUs supported by KVM is used when
# the actual number of physical cores is greater than it.
# WARNING: Be aware that this value impacts the virtual machine's memory footprint and CPU
# the hotplug functionality. For example, `default_maxvcpus = 240` specifies that until 240 vCPUs
# can be added to a SB/VM, but the memory footprint will be big. Another example, with
# `default_maxvcpus = 8` the memory footprint will be small, but 8 will be the maximum number of
# vCPUs supported by the SB/VM. In general, we recommend that you do not edit this variable,
# unless you know what are you doing.
default_maxvcpus = 0

# Bridges can be used to hot plug devices.
# Limitations:
# * Currently only pci bridges are supported
# * Until 30 devices per bridge can be hot plugged.
# * Until 5 PCI bridges can be cold plugged per VM.
#   This limitation could be a bug in qemu or in the kernel
# Default number of bridges per SB/VM:
# unspecified or 0   --> will be set to 1
# > 1 <= 5           --> will be set to the specified number
# > 5                --> will be set to 5
default_bridges = 1

# Default memory size in MiB for SB/VM.
# If unspecified then it will be set 2048 MiB.
default_memory = 2048
#
# Default memory slots per SB/VM.
# If unspecified then it will be set 10.
# This is will determine the times that memory will be hotadded to sandbox/VM.
#memory_slots = 10

# The size in MiB will be plused to max memory of hypervisor.
# It is the memory address space for the NVDIMM devie.
# If set block storage driver (block_device_driver) to "nvdimm",
# should set memory_offset to the size of block device.
# Default 0
#memory_offset = 0

# Disable block device from being used for a container's rootfs.
# In case of a storage driver like devicemapper where a container's 
# root file system is backed by a block device, the block device is passed
# directly to the hypervisor for performance reasons. 
# This flag prevents the block device from being passed to the hypervisor, 
# 9pfs is used instead to pass the rootfs.
disable_block_device_use = false

# Shared file system type:
#   - virtio-9p (default)
#   - virtio-fs
shared_fs = "virtio-9p"

# Path to vhost-user-fs daemon.
virtio_fs_daemon = "/opt/kata/bin/virtiofsd-x86_64"

# Default size of DAX cache in MiB
virtio_fs_cache_size = 1024

# Cache mode:
#
#  - none
#    Metadata, data, and pathname lookup are not cached in guest. They are
#    always fetched from host and any changes are immediately pushed to host.
#
#  - auto
#    Metadata and pathname lookup cache expires after a configured amount of
#    time (default is 1 second). Data is cached while the file is open (close
#    to open consistency).
#
#  - always
#    Metadata, data, and pathname lookup are cached in guest and never expire.
virtio_fs_cache = "always"

# Block storage driver to be used for the hypervisor in case the container
# rootfs is backed by a block device. This is virtio-scsi, virtio-blk
# or nvdimm.
block_device_driver = "virtio-scsi"

# Specifies cache-related options will be set to block devices or not.
# Default false
#block_device_cache_set = true

# Specifies cache-related options for block devices.
# Denotes whether use of O_DIRECT (bypass the host page cache) is enabled.
# Default false
#block_device_cache_direct = true

# Specifies cache-related options for block devices.
# Denotes whether flush requests for the device are ignored.
# Default false
#block_device_cache_noflush = true

# Enable iothreads (data-plane) to be used. This causes IO to be
# handled in a separate IO thread. This is currently only implemented
# for SCSI.
#
enable_iothreads = false

# Enable pre allocation of VM RAM, default false
# Enabling this will result in lower container density
# as all of the memory will be allocated and locked
# This is useful when you want to reserve all the memory
# upfront or in the cases where you want memory latencies
# to be very predictable
# Default false
#enable_mem_prealloc = true

# Enable huge pages for VM RAM, default false
# Enabling this will result in the VM memory
# being allocated using huge pages.
# This is useful when you want to use vhost-user network
# stacks within the container. This will automatically 
# result in memory pre allocation
#enable_hugepages = true

# Enable file based guest memory support. The default is an empty string which
# will disable this feature. In the case of virtio-fs, this is enabled
# automatically and '/dev/shm' is used as the backing folder.
# This option will be ignored if VM templating is enabled.
#file_mem_backend = ""

# Enable swap of vm memory. Default false.
# The behaviour is undefined if mem_prealloc is also set to true
#enable_swap = true

# This option changes the default hypervisor and kernel parameters
# to enable debug output where available. This extra output is added
# to the proxy logs, but only when proxy debug is also enabled.
# 
# Default false
#enable_debug = true

# Disable the customizations done in the runtime when it detects
# that it is running on top a VMM. This will result in the runtime
# behaving as it would when running on bare metal.
# 
#disable_nesting_checks = true

# This is the msize used for 9p shares. It is the number of bytes 
# used for 9p packet payload.
#msize_9p = 8192

# If true and vsocks are supported, use vsocks to communicate directly
# with the agent and no proxy is started, otherwise use unix
# sockets and start a proxy to communicate with the agent.
# Default false
#use_vsock = true

# VFIO devices are hotplugged on a bridge by default. 
# Enable hotplugging on root bus. This may be required for devices with
# a large PCI bar, as this is a current limitation with hotplugging on 
# a bridge. This value is valid for "pc" machine type.
# Default false
#hotplug_vfio_on_root_bus = true

# If host doesn't support vhost_net, set to true. Thus we won't create vhost fds for nics.
# Default false
#disable_vhost_net = true
#
# Default entropy source.
# The path to a host source of entropy (including a real hardware RNG)
# /dev/urandom and /dev/random are two main options.
# Be aware that /dev/random is a blocking source of entropy.  If the host
# runs out of entropy, the VMs boot time will increase leading to get startup
# timeouts.
# The source of entropy /dev/urandom is non-blocking and provides a
# generally acceptable source of entropy. It should work well for pretty much
# all practical purposes.
#entropy_source= "/dev/urandom"

# Path to OCI hook binaries in the *guest rootfs*.
# This does not affect host-side hooks which must instead be added to
# the OCI spec passed to the runtime.
#
# You can create a rootfs with hooks by customizing the osbuilder scripts:
# https://github.com/kata-containers/osbuilder
#
# Hooks must be stored in a subdirectory of guest_hook_path according to their
# hook type, i.e. "guest_hook_path/{prestart,postart,poststop}".
# The agent will scan these directories for executable files and add them, in
# lexicographical order, to the lifecycle of the guest container.
# Hooks are executed in the runtime namespace of the guest. See the official documentation:
# https://github.com/opencontainers/runtime-spec/blob/v1.0.1/config.md#posix-platform-hooks
# Warnings will be logged if any error is encountered will scanning for hooks,
# but it will not abort container execution.
#guest_hook_path = "/usr/share/oci/hooks"

[factory]
# VM templating support. Once enabled, new VMs are created from template
# using vm cloning. They will share the same initial kernel, initramfs and
# agent memory by mapping it readonly. It helps speeding up new container
# creation and saves a lot of memory if there are many kata containers running
# on the same host.
#
# When disabled, new VMs are created from scratch.
#
# Note: Requires "initrd=" to be set ("image=" is not supported).
#
# Default false
#enable_template = true

# Specifies the path of template.
#
# Default "/run/vc/vm/template"
#template_path = "/run/vc/vm/template"

# The number of caches of VMCache:
# unspecified or == 0   --> VMCache is disabled
# > 0                   --> will be set to the specified number
#
# VMCache is a function that creates VMs as caches before using it.
# It helps speed up new container creation.
# The function consists of a server and some clients communicating
# through Unix socket.  The protocol is gRPC in protocols/cache/cache.proto.
# The VMCache server will create some VMs and cache them by factory cache.
# It will convert the VM to gRPC format and transport it when gets
# requestion from clients.
# Factory grpccache is the VMCache client.  It will request gRPC format
# VM and convert it back to a VM.  If VMCache function is enabled,
# kata-runtime will request VM from factory grpccache when it creates
# a new sandbox.
#
# Default 0
#vm_cache_number = 0

# Specify the address of the Unix socket that is used by VMCache.
#
# Default /var/run/kata-containers/cache.sock
#vm_cache_endpoint = "/var/run/kata-containers/cache.sock"

[proxy.kata]
path = "/opt/kata/libexec/kata-containers/kata-proxy"

# If enabled, proxy messages will be sent to the system log
# (default: disabled)
#enable_debug = true

[shim.kata]
path = "/opt/kata/libexec/kata-containers/kata-shim"

# If enabled, shim messages will be sent to the system log
# (default: disabled)
#enable_debug = true

# If enabled, the shim will create opentracing.io traces and spans.
# (See https://www.jaegertracing.io/docs/getting-started).
#
# Note: By default, the shim runs in a separate network namespace. Therefore,
# to allow it to send trace details to the Jaeger agent running on the host,
# it is necessary to set 'disable_new_netns=true' so that it runs in the host
# network namespace.
#
# (default: disabled)
#enable_tracing = true

[agent.kata]
# If enabled, make the agent display debug-level messages.
# (default: disabled)
#enable_debug = true

# Enable agent tracing.
#
# If enabled, the default trace mode is "dynamic" and the
# default trace type is "isolated". The trace mode and type are set
# explicity with the `trace_type=` and `trace_mode=` options.
#
# Notes:
#
# - Tracing is ONLY enabled when `enable_tracing` is set: explicitly
#   setting `trace_mode=` and/or `trace_type=` without setting `enable_tracing`
#   will NOT activate agent tracing.
#
# - See https://github.com/kata-containers/agent/blob/master/TRACING.md for
#   full details.
#
# (default: disabled)
#enable_tracing = true
#
#trace_mode = "dynamic"
#trace_type = "isolated"

[netmon]
# If enabled, the network monitoring process gets started when the
# sandbox is created. This allows for the detection of some additional
# network being added to the existing network namespace, after the
# sandbox has been created.
# (default: disabled)
#enable_netmon = true

# Specify the path to the netmon binary.
path = "/opt/kata/libexec/kata-containers/kata-netmon"

# If enabled, netmon messages will be sent to the system log
# (default: disabled)
#enable_debug = true

[runtime]
# If enabled, the runtime will log additional debug messages to the
# system log
# (default: disabled)
#enable_debug = true
#
# Internetworking model
# Determines how the VM should be connected to the
# the container network interface
# Options:
#
#   - bridged
#     Uses a linux bridge to interconnect the container interface to
#     the VM. Works for most cases except macvlan and ipvlan.
#
#   - macvtap
#     Used when the Container network interface can be bridged using
#     macvtap.
#
#   - none
#     Used when customize network. Only creates a tap device. No veth pair.
#
#   - tcfilter
#     Uses tc filter rules to redirect traffic from the network interface
#     provided by plugin to a tap interface connected to the VM.
#
internetworking_model="tcfilter"

# disable guest seccomp
# Determines whether container seccomp profiles are passed to the virtual
# machine and applied by the kata agent. If set to true, seccomp is not applied
# within the guest
# (default: true)
disable_guest_seccomp=true

# If enabled, the runtime will create opentracing.io traces and spans.
# (See https://www.jaegertracing.io/docs/getting-started).
# (default: disabled)
#enable_tracing = true

# If enabled, the runtime will not create a network namespace for shim and hypervisor processes.
# This option may have some potential impacts to your host. It should only be used when you know what you're doing.
# `disable_new_netns` conflicts with `enable_netmon`
# `disable_new_netns` conflicts with `internetworking_model=bridged` and `internetworking_model=macvtap`. It works only
# with `internetworking_model=none`. The tap device will be in the host network namespace and can connect to a bridge
# (like OVS) directly.
# If you are using docker, `disable_new_netns` only works with `docker run --net=none`
# (default: false)
#disable_new_netns = true

# Enabled experimental feature list, format: ["a", "b"].
# Experimental features are features not stable enough for production,
# They may break compatibility, and are prepared for a big version bump.
# Supported experimental features:
# 1. "newstore": new persist storage driver which breaks backward compatibility,
#				expected to move out of experimental in 2.0.0.
# (default: [])
experimental=[]

Config file /usr/share/defaults/kata-containers/configuration.toml not found

---

KSM throttler

version

Output of " --version":

./kata-collect-data.sh: line 178: --version: command not found

systemd service

Image details

---
osbuilder:
  url: "https://github.com/kata-containers/osbuilder"
  version: "unknown"
rootfs-creation-time: "2019-07-22T00:55:25.248493513+0000Z"
description: "osbuilder rootfs"
file-format-version: "0.0.2"
architecture: "x86_64"
base-distro:
  name: "bionic"
  version: "18.04"
  packages:
    default:
      - "systemd,iptables,init,chrony,fuse,bash"
    extra:
      - "bash"
      - "fuse"
agent:
  url: "https://github.com/kata-containers/agent"
  name: "kata-agent"
  version: "1.8.0-3195c3e48c50dc835ab84d6b4ced397659369fb8"
  agent-is-init-daemon: "no"

---

Initrd details

No initrd

---

Logfiles

Runtime logs

No recent runtime problems found in system journal.

Proxy logs

No recent proxy problems found in system journal.

Shim logs

No recent shim problems found in system journal.

Throttler logs

No recent throttler problems found in system journal.

---

Container manager details

Have docker

Docker

Output of "docker version":

Client:
 Version:           18.06.3-ce
 API version:       1.38
 Go version:        go1.10.8
 Git commit:        d7080c1
 Built:             Tue Feb 19 23:07:53 2019
 OS/Arch:           linux/amd64
 Experimental:      false
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Output of "docker info":

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Output of "systemctl show docker":

Restart=no
NotifyAccess=none
RestartUSec=100ms
TimeoutStartUSec=1min 30s
TimeoutStopUSec=1min 30s
RuntimeMaxUSec=infinity
WatchdogUSec=0
WatchdogTimestampMonotonic=0
RootDirectoryStartOnly=no
RemainAfterExit=no
GuessMainPID=yes
MainPID=0
ControlPID=0
FileDescriptorStoreMax=0
NFileDescriptorStore=0
StatusErrno=0
Result=success
UID=[not set]
GID=[not set]
NRestarts=0
ExecMainStartTimestampMonotonic=0
ExecMainExitTimestampMonotonic=0
ExecMainPID=0
ExecMainCode=0
ExecMainStatus=0
MemoryCurrent=[not set]
CPUUsageNSec=[not set]
TasksCurrent=[not set]
IPIngressBytes=18446744073709551615
IPIngressPackets=18446744073709551615
IPEgressBytes=18446744073709551615
IPEgressPackets=18446744073709551615
Delegate=no
CPUAccounting=no
CPUWeight=[not set]
StartupCPUWeight=[not set]
CPUShares=[not set]
StartupCPUShares=[not set]
CPUQuotaPerSecUSec=infinity
IOAccounting=no
IOWeight=[not set]
StartupIOWeight=[not set]
BlockIOAccounting=no
BlockIOWeight=[not set]
StartupBlockIOWeight=[not set]
MemoryAccounting=yes
MemoryMin=0
MemoryLow=0
MemoryHigh=infinity
MemoryMax=infinity
MemorySwapMax=infinity
MemoryLimit=infinity
DevicePolicy=auto
TasksAccounting=yes
TasksMax=73727
IPAccounting=no
UMask=0022
LimitCPU=infinity
LimitCPUSoft=infinity
LimitFSIZE=infinity
LimitFSIZESoft=infinity
LimitDATA=infinity
LimitDATASoft=infinity
LimitSTACK=infinity
LimitSTACKSoft=8388608
LimitCORE=infinity
LimitCORESoft=infinity
LimitRSS=infinity
LimitRSSSoft=infinity
LimitNOFILE=1073741816
LimitNOFILESoft=1073741816
LimitAS=infinity
LimitASSoft=infinity
LimitNPROC=2063281
LimitNPROCSoft=2063281
LimitMEMLOCK=67108864
LimitMEMLOCKSoft=67108864
LimitLOCKS=infinity
LimitLOCKSSoft=infinity
LimitSIGPENDING=2063281
LimitSIGPENDINGSoft=2063281
LimitMSGQUEUE=819200
LimitMSGQUEUESoft=819200
LimitNICE=0
LimitNICESoft=0
LimitRTPRIO=0
LimitRTPRIOSoft=0
LimitRTTIME=infinity
LimitRTTIMESoft=infinity
OOMScoreAdjust=0
Nice=0
IOSchedulingClass=0
IOSchedulingPriority=0
CPUSchedulingPolicy=0
CPUSchedulingPriority=0
TimerSlackNSec=50000
CPUSchedulingResetOnFork=no
NonBlocking=no
StandardInput=null
StandardInputData=
StandardOutput=inherit
StandardError=inherit
TTYReset=no
TTYVHangup=no
TTYVTDisallocate=no
SyslogPriority=30
SyslogLevelPrefix=yes
SyslogLevel=6
SyslogFacility=3
LogLevelMax=-1
LogRateLimitIntervalUSec=0
LogRateLimitBurst=0
SecureBits=0
CapabilityBoundingSet=cap_chown cap_dac_override cap_dac_read_search cap_fowner cap_fsetid cap_kill cap_setgid cap_setuid cap_setpcap cap_linux_immutable cap_net_bind_service cap_net_broadcast cap_net_admin cap_net_raw cap_ipc_lock cap_ipc_owner cap_sys_module cap_sys_rawio cap_sys_chroot cap_sys_ptrace cap_sys_pacct cap_sys_admin cap_sys_boot cap_sys_nice cap_sys_resource cap_sys_time cap_sys_tty_config cap_mknod cap_lease cap_audit_write cap_audit_control cap_setfcap cap_mac_override cap_mac_admin cap_syslog cap_wake_alarm cap_block_suspend
AmbientCapabilities=
DynamicUser=no
RemoveIPC=no
MountFlags=
PrivateTmp=no
PrivateDevices=no
ProtectKernelTunables=no
ProtectKernelModules=no
ProtectControlGroups=no
PrivateNetwork=no
PrivateUsers=no
PrivateMounts=no
ProtectHome=no
ProtectSystem=no
SameProcessGroup=no
UtmpMode=init
IgnoreSIGPIPE=yes
NoNewPrivileges=no
SystemCallErrorNumber=0
LockPersonality=no
RuntimeDirectoryPreserve=no
RuntimeDirectoryMode=0755
StateDirectoryMode=0755
CacheDirectoryMode=0755
LogsDirectoryMode=0755
ConfigurationDirectoryMode=0755
MemoryDenyWriteExecute=no
RestrictRealtime=no
RestrictNamespaces=no
MountAPIVFS=no
KeyringMode=private
KillMode=control-group
KillSignal=15
FinalKillSignal=9
SendSIGKILL=yes
SendSIGHUP=no
WatchdogSignal=6
Id=docker.service
Names=docker.service
WantedBy=kitt-init.service
ConsistsOf=docker.socket
Before=kitt-init.service
After=docker.socket
TriggeredBy=docker.socket
Description=docker.service
LoadState=masked
ActiveState=inactive
SubState=dead
FragmentPath=/dev/null
UnitFileState=masked
StateChangeTimestampMonotonic=0
InactiveExitTimestampMonotonic=0
ActiveEnterTimestampMonotonic=0
ActiveExitTimestampMonotonic=0
InactiveEnterTimestampMonotonic=0
CanStart=no
CanStop=yes
CanReload=no
CanIsolate=no
StopWhenUnneeded=no
RefuseManualStart=no
RefuseManualStop=no
AllowIsolate=no
DefaultDependencies=yes
OnFailureJobMode=replace
IgnoreOnIsolate=no
NeedDaemonReload=no
JobTimeoutUSec=infinity
JobRunningTimeoutUSec=infinity
JobTimeoutAction=none
ConditionResult=no
AssertResult=no
ConditionTimestampMonotonic=0
AssertTimestampMonotonic=0
LoadError=org.freedesktop.systemd1.UnitMasked "Unit docker.service is masked."
Transient=no
Perpetual=no
StartLimitIntervalUSec=10s
StartLimitBurst=5
StartLimitAction=none
FailureAction=none
FailureActionExitStatus=-1
SuccessAction=none
SuccessActionExitStatus=-1
CollectMode=inactive

No kubectl
No crio
Have containerd

containerd

Output of "containerd --version":

containerd github.com/containerd/containerd v1.2.0-575-gb99a66c2 b99a66c267d04740628634d7d038f9ce1753b339

Output of "systemctl show containerd":

Type=simple
Restart=always
NotifyAccess=none
RestartUSec=5s
TimeoutStartUSec=1min 30s
TimeoutStopUSec=1min 30s
RuntimeMaxUSec=infinity
WatchdogUSec=0
WatchdogTimestampMonotonic=0
RootDirectoryStartOnly=no
RemainAfterExit=no
GuessMainPID=yes
MainPID=22071
ControlPID=0
FileDescriptorStoreMax=0
NFileDescriptorStore=0
StatusErrno=0
Result=success
UID=[not set]
GID=[not set]
NRestarts=0
ExecMainStartTimestamp=Mon 2019-07-22 01:54:53 UTC
ExecMainStartTimestampMonotonic=752780330
ExecMainExitTimestampMonotonic=0
ExecMainPID=22071
ExecMainCode=0
ExecMainStatus=0
ExecStartPre={ path=/sbin/modprobe ; argv[]=/sbin/modprobe overlay ; ignore_errors=no ; start_time=[Mon 2019-07-22 01:54:50 UTC] ; stop_time=[Mon 2019-07-22 01:54:50 UTC] ; pid=21979 ; code=exited ; status=0 }
ExecStartPre={ path=/opt/bin/containerd-init.sh ; argv[]=/opt/bin/containerd-init.sh ; ignore_errors=no ; start_time=[Mon 2019-07-22 01:54:50 UTC] ; stop_time=[Mon 2019-07-22 01:54:53 UTC] ; pid=21980 ; code=exited ; status=0 }
ExecStart={ path=/opt/containerd/bin/containerd ; argv[]=/opt/containerd/bin/containerd --log-level=info --config=/etc/containerd/config.toml ; ignore_errors=no ; start_time=[Mon 2019-07-22 01:54:53 UTC] ; stop_time=[n/a] ; pid=22071 ; code=(null) ; status=0/0 }
Slice=system.slice
ControlGroup=/system.slice/containerd.service
MemoryCurrent=3014160384
CPUUsageNSec=[not set]
TasksCurrent=283
IPIngressBytes=18446744073709551615
IPIngressPackets=18446744073709551615
IPEgressBytes=18446744073709551615
IPEgressPackets=18446744073709551615
Delegate=yes
DelegateControllers=cpu cpuacct io blkio memory devices pids bpf-firewall bpf-devices
CPUAccounting=no
CPUWeight=[not set]
StartupCPUWeight=[not set]
CPUShares=[not set]
StartupCPUShares=[not set]
CPUQuotaPerSecUSec=infinity
IOAccounting=no
IOWeight=[not set]
StartupIOWeight=[not set]
BlockIOAccounting=no
BlockIOWeight=[not set]
StartupBlockIOWeight=[not set]
MemoryAccounting=yes
MemoryMin=0
MemoryLow=0
MemoryHigh=infinity
MemoryMax=infinity
MemorySwapMax=infinity
MemoryLimit=infinity
DevicePolicy=auto
TasksAccounting=yes
TasksMax=73727
IPAccounting=no
UMask=0022
LimitCPU=infinity
LimitCPUSoft=infinity
LimitFSIZE=infinity
LimitFSIZESoft=infinity
LimitDATA=infinity
LimitDATASoft=infinity
LimitSTACK=infinity
LimitSTACKSoft=8388608
LimitCORE=infinity
LimitCORESoft=infinity
LimitRSS=infinity
LimitRSSSoft=infinity
LimitNOFILE=1048576
LimitNOFILESoft=1048576
LimitAS=infinity
LimitASSoft=infinity
LimitNPROC=infinity
LimitNPROCSoft=infinity
LimitMEMLOCK=65536
LimitMEMLOCKSoft=65536
LimitLOCKS=infinity
LimitLOCKSSoft=infinity
LimitSIGPENDING=2063281
LimitSIGPENDINGSoft=2063281
LimitMSGQUEUE=819200
LimitMSGQUEUESoft=819200
LimitNICE=0
LimitNICESoft=0
LimitRTPRIO=0
LimitRTPRIOSoft=0
LimitRTTIME=infinity
LimitRTTIMESoft=infinity
OOMScoreAdjust=-999
Nice=0
IOSchedulingClass=0
IOSchedulingPriority=0
CPUSchedulingPolicy=0
CPUSchedulingPriority=0
TimerSlackNSec=50000
CPUSchedulingResetOnFork=no
NonBlocking=no
StandardInput=null
StandardInputData=
StandardOutput=journal
StandardError=inherit
TTYReset=no
TTYVHangup=no
TTYVTDisallocate=no
SyslogPriority=30
SyslogLevelPrefix=yes
SyslogLevel=6
SyslogFacility=3
LogLevelMax=-1
LogRateLimitIntervalUSec=0
LogRateLimitBurst=0
SecureBits=0
CapabilityBoundingSet=cap_chown cap_dac_override cap_dac_read_search cap_fowner cap_fsetid cap_kill cap_setgid cap_setuid cap_setpcap cap_linux_immutable cap_net_bind_service cap_net_broadcast cap_net_admin cap_net_raw cap_ipc_lock cap_ipc_owner cap_sys_module cap_sys_rawio cap_sys_chroot cap_sys_ptrace cap_sys_pacct cap_sys_admin cap_sys_boot cap_sys_nice cap_sys_resource cap_sys_time cap_sys_tty_config cap_mknod cap_lease cap_audit_write cap_audit_control cap_setfcap cap_mac_override cap_mac_admin cap_syslog cap_wake_alarm cap_block_suspend
AmbientCapabilities=
DynamicUser=no
RemoveIPC=no
MountFlags=
PrivateTmp=no
PrivateDevices=no
ProtectKernelTunables=no
ProtectKernelModules=no
ProtectControlGroups=no
PrivateNetwork=no
PrivateUsers=no
PrivateMounts=no
ProtectHome=no
ProtectSystem=no
SameProcessGroup=no
UtmpMode=init
IgnoreSIGPIPE=yes
NoNewPrivileges=no
SystemCallErrorNumber=0
LockPersonality=no
RuntimeDirectoryPreserve=no
RuntimeDirectoryMode=0755
StateDirectoryMode=0755
CacheDirectoryMode=0755
LogsDirectoryMode=0755
ConfigurationDirectoryMode=0755
MemoryDenyWriteExecute=no
RestrictRealtime=no
RestrictNamespaces=no
MountAPIVFS=no
KeyringMode=private
KillMode=process
KillSignal=15
FinalKillSignal=9
SendSIGKILL=yes
SendSIGHUP=no
WatchdogSignal=6
Id=containerd.service
Names=containerd.service
Requires=system.slice sysinit.target
WantedBy=multi-user.target
Conflicts=shutdown.target
Before=shutdown.target multi-user.target
After=containerd-devicemapper-init.service basic.target kata-init.service sysinit.target system.slice systemd-journald.socket
Documentation=https://containerd.io
Description=containerd container runtime
LoadState=loaded
ActiveState=active
SubState=running
FragmentPath=/etc/systemd/system/containerd.service
UnitFileState=enabled
UnitFilePreset=enabled
StateChangeTimestamp=Mon 2019-07-22 01:54:53 UTC
StateChangeTimestampMonotonic=752780381
InactiveExitTimestamp=Mon 2019-07-22 01:54:50 UTC
InactiveExitTimestampMonotonic=750181982
ActiveEnterTimestamp=Mon 2019-07-22 01:54:53 UTC
ActiveEnterTimestampMonotonic=752780381
ActiveExitTimestamp=Mon 2019-07-22 01:54:50 UTC
ActiveExitTimestampMonotonic=750173118
InactiveEnterTimestamp=Mon 2019-07-22 01:54:50 UTC
InactiveEnterTimestampMonotonic=750179863
CanStart=yes
CanStop=yes
CanReload=no
CanIsolate=no
StopWhenUnneeded=no
RefuseManualStart=no
RefuseManualStop=no
AllowIsolate=no
DefaultDependencies=yes
OnFailureJobMode=replace
IgnoreOnIsolate=no
NeedDaemonReload=no
JobTimeoutUSec=infinity
JobRunningTimeoutUSec=infinity
JobTimeoutAction=none
ConditionResult=yes
AssertResult=yes
ConditionTimestamp=Mon 2019-07-22 01:54:50 UTC
ConditionTimestampMonotonic=750180484
AssertTimestamp=Mon 2019-07-22 01:54:50 UTC
AssertTimestampMonotonic=750180485
Transient=no
Perpetual=no
StartLimitIntervalUSec=10s
StartLimitBurst=5
StartLimitAction=none
FailureAction=none
FailureActionExitStatus=-1
SuccessAction=none
SuccessActionExitStatus=-1
InvocationID=c1ed7b0c9c6c4059905831c506e24b53
CollectMode=inactive

Output of "cat /etc/containerd/config.toml":

[grpc]
address = "/run/containerd/containerd.sock"
uid = 0
gid = 0

[plugins]
  [plugins.devmapper]
    pool_name = "containerd-thinpool"
    base_image_size = "32GB"
  [plugins.cri.containerd]
    snapshotter = "overlayfs"
    [plugins.cri.containerd.default_runtime]
      runtime_type = "io.containerd.runtime.v1.linux"
      runtime_engine = "/usr/bin/runc"
      runtime_root = ""
    [plugins.cri.containerd.untrusted_workload_runtime]
      runtime_type = "io.containerd.kata.v2"

[plugins.cri]
  max_container_log_line_size = 262144

[plugins.linux]
  shim = "/opt/containerd/bin/containerd-shim"
  runtime = "runc"

[plugins.cri.registry]
  [plugins.cri.registry.mirrors]
    [plugins.cri.registry.mirrors."docker.io"]
       endpoint = []

---

Packages

No dpkg
No rpm

---

[bergwolf]

@awprice Could you re-try with virtio_fs_cache = "none" in the config.toml?

[awprice]

@awprice Could you re-try with virtio_fs_cache = "none" in the config.toml?

@bergwolf See issue description:

Switching virtio_fs_cache to none works, but we've experienced other commands failing, e.g. apt-get update. Switching to none isn't really ideal as we like the performance benefits of auto/always.

[bergwolf]

@awprice The problem is caused by guest kernel cache. With auto/always, data is cached in the guest and later flushed to the guest. So you cannot expect to read guest writes immediately on the host. This is the design of the two cache modes.

One possible workaround is for the guest app to use mmap to read/write the file. The guest page cache is mmaped to the app and it is actually backed by the host page cache with virtio-fs dax option. Then you can get immediate data access on the host by using only one layer of cache.

[awprice]

@bergwolf Just to clarify, the file is being written from the host side by containerd and we are reading from it from an app on the guest. We aren't seeing the file being updated inside the VM until an fstat syscall is called on it.

[bergwolf]

@awprice Looks like the same thing vice versa ;) The two cache modes make guest kernel trust its local inode attribute thus does not know what's happening on the host side.

[egernst]

@dagrh @ganeshmaharaj PTAL

[rhvgoyal]

@bergwolf Just to clarify, the file is being written from the host side by containerd and we are reading from it from an app on the guest. We aren't seeing the file being updated inside the VM until an fstat syscall is called on it.

For this immediate synchornization between host and guest, you will need cache=none. Are you extending file size? If not, with DAX enabled, even with cache=auto/always, you should see host written data in guest immediately (as guest is not caching any data, only metadata is being cached. All data access is through dax in guest which is mapping host cache which is up to date already).

[awprice]

Thanks for the explanation @bergwolf, @rhvgoyal. From what I understand this is desired behaviour?

@rhvgoyal One question about this:

Are you extending file size?

We are changing the file size (appending log lines), so why doesn't the cache get invalidated when file size changes?

@egernst Would it be worthwhile adding some documentation somewhere documenting this? It's a change in behaviour from 9p -> virtio-fs, so it will likely trip others up.

My only other concern is related to Kubernetes secrets/configmaps and service account tokens, which are mounted into the VM. These can be changed by the kubelet on the host side. Is this cache behaviour going to pose an issue for those use cases?

[bergwolf]

These can be changed by the kubelet on the host side. Is this cache behaviour going to pose an issue for those use cases?

For this case we might be able to specially optimize for it for cache=auto/always modes. E.g., we tell virtiofsd which file/directory to watch at (via inotify or fanotify etc.). Then when the watched file/directory changes, send fuse notifications to the guest kernel to invalidate corresponding caches. In the kata host share dir, we can create a watched directory and bind mount k8s specific files there and pass to the guest. @rhvgoyal wdyt?

[rhvgoyal]

These can be changed by the kubelet on the host side. Is this cache behaviour going to pose an issue for those use cases?

For this case we might be able to specially optimize for it for cache=auto/always modes. E.g., we tell virtiofsd which file/directory to watch at (via inotify or fanotify etc.). Then when the watched file/directory changes, send fuse notifications to the guest kernel to invalidate corresponding caches. In the kata host share dir, we can create a watched directory and bind mount k8s specific files there and pass to the guest. @rhvgoyal wdyt?

For now, if you want cache coherency with host, one will have to use cache=none. With cache=always, virtio-fs still does not handle cache coherency with host/other guests. Bunch of ideas are in flux but nothing is finalized yet. Once a basic version of virtio-fs is upstream and handles basic use cases well, we will have to move to next stage of provide cache coherency with cache=auto/always as well.

[ganeshmaharaj]

These can be changed by the kubelet on the host side. Is this cache behaviour going to pose an issue for those use cases?

For this case we might be able to specially optimize for it for cache=auto/always modes. E.g., we tell virtiofsd which file/directory to watch at (via inotify or fanotify etc.). Then when the watched file/directory changes, send fuse notifications to the guest kernel to invalidate corresponding caches. In the kata host share dir, we can create a watched directory and bind mount k8s specific files there and pass to the guest. @rhvgoyal wdyt?

For now, if you want cache coherency with host, one will have to use cache=none. With cache=always,
In this case, there would be a performance hit isn't it @rhvgoyal ?

[rhvgoyal]

For now, if you want cache coherency with host, one will have to use cache=none. With cache=always,
In this case, there would be a performance hit isn't it @rhvgoyal ?

Yes, there will be. But correctness is first goal and performance is secondary goal once correctness has been achieved. So if your use case requires that you update file on host and that change become visible immediately inside guest, you need to use cache=none.

[ganeshmaharaj]

@awprice now that we landed the fix for cache=none, I am guessing this use-case will work? Will try to test this asap and confirm what i find.

[awprice]

I'm going to close this out, with the following recommendation for anyone that comes across the same issue -

• Switch to cache=none to disable the virtio-fs cache to get instant host file updates
• Call stat in your program before reading the file to ensure the latest version is fetched