Add Ignite usage documentation

docs/REQUIREMENTS.md

@@ -14,8 +14,8 @@ Everything apart from above, is not supported, and out of scope.
 
  - A host running Linux 4.14 or newer
  - An Intel or AMD (alpha) CPU
- - `sysctl net.bridge.bridge-nf-call-iptables=0`
  - `sysctl net.ipv4.ip_forward=1`
+ - Optional: `sysctl net.bridge.bridge-nf-call-iptables=0`
 
 ### Guest Requirements
 

docs/installation.md

@@ -0,0 +1,45 @@
+# Ignite installation guide
+
+This guide describes the installation and uninstallation process of Ignite.
+
+## System requirements
+
+Ignite runs on any Intel-based `linux/amd64` system with `KVM` enabled.
+AMD support is in alpha (Firecracker limitation).
+
+See the [requirements](REQUIREMENTS.md) for needed dependencies.
+
+## Downloading the binary
+Ignite is a currently a single binary application. To install it,
+download the binary from the [GitHub releases page](https://github.com/weaveworks/ignite/releases),
+save it as `/usr/local/bin/ignite` and make it executable.
+
+To install Ignite from the command line, execute the following in a `root` shell
+(or use `sudo` for `curl` and `chmod`):
+```bash
+export VERSION=0.3.0
+curl -Lo /usr/local/bin/ignite https://github.com/weaveworks/ignite/releases/download/v${VERSION}/ignite
+chmod +x /usr/local/bin/ignite
+```
+
+Ignite uses [semantic versioning](https://semver.org), select the version to be installed
+by changing the `VERSION` environment variable.
+
+## Verifying the installation
+
+If the installation was successful, the `ignite` command should now be available:
+```
+# ignite version
+Ignite version: version.Info{Major:"0", Minor:"3", GitVersion:"v0.3.0", GitCommit:"9db63f66c8a38c83212d618f6d0d6995b79e07bf", GitTreeState:"clean", BuildDate:"2019-06-18T13:30:59Z", GoVersion:"go1.12.1", Compiler:"gc", Platform:"linux/amd64"}
+Firecracker version: v0.16.0
+```
+
+## Removing the installation
+
+**NOTE:** Make sure no virtual machines are running before executing this step.
+
+To completely remove the Ignite installation, execute the following as root:
+```bash
+rm -r /var/lib/firecracker
+rm /usr/local/bin/ignite
+```

docs/usage.md

@@ -0,0 +1,231 @@
+# How to use Ignite to run VMs
+
+Ignite is a containerized Firecracker microVM administration tool.
+It runs and manages virtual machines in separate containers
+using [Firecracker](https://firecracker-microvm.github.io/).
+
+This is a quick guide on how to get started with Ignite. 
+The guide will cover the following topics in order:
+ - [Importing a VM base image](#importing-a-vm-base-image)
+ - [Creating a new VM based on the imported image](#creating-a-new-vm-based-on-the-imported-image)
+ - [Options for VM generation](#options-for-vm-generation)
+ - [Starting a VM](#starting-a-vm)
+ - [Inspecting VMs and their resources](#inspecting-vms-and-their-resources)
+ - [Accessing a VM](#accessing-a-vm)
+ - [Attaching to the TTY](#attaching-to-the-tty)
+ - [SSH into the VM](#ssh-into-the-vm)
+ - [All in one](#all-in-one)
+ - [Stopping a VM](#stopping-a-vm)
+ - [Removing a VM](#removing-a-vm)
+ - [Removing other resources](#removing-other-resources)
+
+Keep in mind that all Ignite commands require `root` for now.
+This will change later.
+
+### Importing a VM base image
+
+A VM base image (or just `image`) is an OCI container, which contains a filesystem
+and has an init system installed. Ignite currently supports importing `images` from
+Docker images, for which it has the following command:
+
+```
+# ignite image import <identifier>
+```
+
+The identifier can either be the UID of the image in Docker, or its name. If using the
+name without specifying a tag, `:latest` is automatically appended. Ignite can also match
+a prefix of the given name/UID in any command provided that it's unique, so you can e.g.
+enter just the three first letters of a name if they are unique to a single resource.
+
+Go ahead and import the `weaveworks/ignite-ubuntu` Docker image. If it isn't present locally,
+Ignite will pull it for you:
+
+```
+# ignite image import weaveworks/ignite-ubuntu
+...
+INFO[0002] Created image with ID "cae0ac317cca74ba" and name "weaveworks/ignite-ubuntu:latest" 
+```
+
+Now the `weaveworks/ignite-ubuntu` image is imported and ready for VM use.
+
+### Creating a new VM based on the imported image
+
+The `images` are read-only references of what every VM based on them should contain.
+To create a functional `VM`, Ignite uses `device mapper` to overlay a writable snapshot
+on top of the `image`. All changes to the `VM` will be saved in the snapshot.
+
+Let's create a new VM with some options:
+
+```
+# ignite create weaveworks/ignite-ubuntu \
+ --name my-vm \
+ --cpus 2 \
+ --memory 1GB \
+ --size 6GB \
+ --ssh
+...
+INFO[0001] Created VM with ID "3c5fa9a18682741f" and name "my-vm" 
+```
+
+#### Options for VM generation
+
+The previous example tells Ignite to create a `VM` with the name `my-vm` and that it should have
+2 CPU cores, 1 GB of RAM, a writable snapshot size of 6 GB and have SSH access enabled.
+
+The snapshot stores a delta compared to the base `image`, so a `--size` of "6GB" enables
+storing 6 Gigabytes of data changes (addition or removal).
+
+The `--ssh` flag generates a new private/public key pair
+for the `VM` and exports the public key it into the `VM`.
+This is used for `ignite ssh <identifier>` later.
+
+All available options can be listed with `ignite create --help`.
+
+## Starting a VM
+
+Starting a created `VM` is very straight forward:
+
+```
+# ignite start my-vm
+```
+
+The `VM` will be matched by its name or ID (useful if there are similarly named `VMs`).
+
+If no error occured, your `VM` is now running.
+
+## Inspecting VMs and their resources
+
+Ignite currently manages three kinds of resources: `images`, `kernels` and `VMs`.
+The `kernels` are quite transparent, and get automatically imported from the docker
+image `weaveworks/ignite-kernel:4.19.47` by default (overridable during `create`).
+
+To list the available `kernels`, enter:
+```
+# ignite kernels
+KERNEL ID NAME CREATED SIZE VERSION
+aefb459546315344 weaveworks/ignite-kernel:4.19.47 61m ago 49.0 MB 4.19.47
+```
+
+To list the imported `images`, enter:
+```
+# ignite images
+IMAGE ID NAME CREATED SIZE
+cae0ac317cca74ba weaveworks/ignite-ubuntu:latest 82m ago 268.9 MB
+```
+
+And to list the running `VMs`, enter:
+```
+# ignite ps
+VM ID IMAGE KERNEL CREATED SIZE CPUS MEMORY STATE IPS PORTS NAME
+3c5fa9a18682741f weaveworks/ignite-ubuntu:latest weaveworks/ignite-kernel:4.19.47 63m ago 4.0 GB 2 1.0 GB Running 172.17.0.3 my-vm
+```
+To list all `VMs` instead of just running ones, add the `-a` flag to `ps`.
+
+## Accessing a VM
+
+Ignite has two ways to access a CLI in a `VM`, the first option is to attach to the `VM's` TTY
+and the other is to SSH into the `VM`.
+
+### Attaching to the TTY
+
+To attach to the running `VM's` TTY, enter:
+```
+# ignite attach my-vm
+3c5fa9a18682741f
+<enter>
+Ubuntu 18.04.2 LTS 3c5fa9a18682741f ttyS0
+
+3c5fa9a18682741f login:
+```
+If nothing is displayed, hit Enter to re-display the login prompt.
+Login using the credentials set in the `image` (usually `root` with password `root`).
+
+**To detach** from the TTY, enter the key combination **^P^Q** (Ctrl + P + Q):
+```
+root@3c5fa9a18682741f:~# <^P^Q> read escape sequence
+$
+```
+
+### SSH into the VM
+
+**NOTE:** SSH works only if the `--ssh` flag is specified during `create`. Otherwise there are
+no public keys imported into the `VM` and most `images` have password-based root logins
+disabled for security reasons.
+
+To SSH into a `VM`, enter:
+```
+# ignite ssh my-vm
+Welcome to Ubuntu 18.04.2 LTS (GNU/Linux 4.19.47 x86_64)
+...
+root@3c5fa9a18682741f:~#
+```
+
+To exit SSH, just quit the shell process with `exit`.
+
+**NOTE:** Each SSH access spawns its own session, but TTY access
+via `attach` is **shared**, every attached user operates the same terminal.
+
+## All in one
+
+Ignite has a shorthand for peforming `image import`, `create`, `start` and possibly also `attach`
+all in one command:
+
+```
+# ignite run weaveworks/ignite-ubuntu \
+ --name another-vm \
+ --cpus 2 \
+ --memory 1GB \
+ --size 6GB \
+ --ssh \
+ --interactive
+```
+
+This imports the given `image`, creates a new `VM` from it, starts the `VM` and attaches to the `VM's` TTY.
+
+`run` accepts all the flags for `image import`, `create` and `start`. Using the `--interactive`
+flag of `start`, an `attach` is performed right after the `VM` has been started.
+
+## Stopping a VM
+
+Ignite `VMs` can be stopped three ways:
+1. By running: `# ignite stop my-vm`
+2. By running: `# ignite kill my-vm`
+3. By issuing the `reboot` command inside the VM
+
+If the `VM's` `kernel` has support for Firecracker's virtual keyboard, `stop` will issue
+Ctrl + Alt + Del to gracefully shut down the `VM`. It will wait 20 seconds for Firecracker
+to exit, after which the `VM` will be forcibly killed.
+
+`kill` is an alias for `stop -f`, which force-kills the `VM`. **WARNING:** The `VM` is given
+no time to close open resources, so this might lead to data loss or filesystem corruption.
+
+Issuing `reboot` inside the `VM` is the recommended way to stop a `VM` that doesn't support
+Firecracker's virtual keyboard. By _rebooting_ the `VM` Firecracker _shuts itself down gracefully_.
+
+**NOTE:** Do _not_ enter `shutdown` or `halt` inside the `VM`, this will result in
+Firecracker hanging.
+
+## Removing a VM
+
+To remove `VMs` in Ignite, use the following command:
+```
+# ignite rm my-vm
+```
+
+The `VM` needs to not be running for this to succeed. Using the `--force` flag
+a running `VM` can also be removed, it will be killed before removal.
+
+## Removing other resources
+
+To remove an `image`, run:
+```
+# ignite rmi weaveworks/ignite-ubuntu
+```
+
+And to remove a `kernel`, run:
+```
+# ignite rmk weaveworks/ignite-kernel:4.19.47
+```
+
+**NOTE:** To fully uninstall all Ignite data, remove the data directory
+at `/var/lib/firecracker`. Remember to stop all running `VMs` before doing this.