vr_dns

DNS

This feature implements a DNS recursor, the main use case of it would be to provide DNS to VMs running inside an isolated (no Internet access), private VNET.

Virtual Router Configuration

The following attributes control the basic DNS configuration:

• ONEAPP_VNF_DNS_ENABLED to enable the DNS server
• ONEAPP_VNF_DNS_INTERFACES list of interface names to listen for DNS requests.

For example to enable the recursor on a private network connected to the eth1 NIC:

CONTEXT = [
  ...
  ONEAPP_VNF_DNS_ENABLED    = "YES",
  ONEAPP_VNF_DNS_INTERFACES = "eth1",
  ...
]

You should use the Virtual Router IP (or FLOATING_IP) as the Virtual Network DNS. So for example if your Virtual Router includes:

CONTEXT = [
  ...
  ONEAPP_VROUTER_ETH1_VIP0 = "172.20.0.123",
  ...
]

Then your private Virtual Network should have DNS parameter set to 172.20.0.123 (VIP).

$ onevnet show private -j | jq -r .VNET.TEMPLATE.DNS
172.20.0.123

Context Configuration Attributes

Parameter	Default	Description
ONEAPP_VNF_DNS_ENABLED	NO	Enable/Disable DNS feature (YES/NO)
ONEAPP_VNF_DNS_INTERFACES	all NICs	List of NICs to listen on (<[!]ethX> ...)
ONEAPP_VNF_DNS_MAX_CACHE_TTL	3600	Maximum caching time (seconds)
ONEAPP_VNF_DNS_USE_ROOTSERVERS	YES	Use root name servers directly (YES/NO)
ONEAPP_VNF_DNS_NAMESERVERS	none	List of upstream NSs to forward queries to (<IP>[@<PORT>] ...)
ONEAPP_VNF_DNS_UPSTREAM_TIMEOUT	1128	Upstream NS connection timeout (milliseconds)
ONEAPP_VNF_DNS_ALLOWED_NETWORKS	all SNs	Client networks from which is allowed to make queries (<network>/<prefix> ...)
ONEAPP_VNF_DNS_TCP_DISABLED	NO	Enable/Disable service over TCP (YES/NO)
ONEAPP_VNF_DNS_UDP_DISABLED	NO	Enable/Disable service over UDP (YES/NO)
ONEAPP_VNF_DNS_CLUSTER_DOMAIN	vr	Expose ipX.ethY.vr, vipX.ethY.vr and epX.ethY.vr DNS local-zone names

IP / VIP / EP Local-Zone Domain Names

Similarly to IP / VIP / EP Placeholders same logic is reused by the DNS feature. When ONEAPP_VNF_DNS_CLUSTER_DOMAIN context variable is non-empty, then the recursor (unbound) exposes ipX.ethY.<ONEAPP_VNF_DNS_CLUSTER_DOMAIN>, vipX.ethY.<ONEAPP_VNF_DNS_CLUSTER_DOMAIN>, epX.ethY.<ONEAPP_VNF_DNS_CLUSTER_DOMAIN> domain names, so they can be accessed from VNETs attached to the VR.

The primary use case for these domain names would be to always have identical endpoints regardless of the underlying VNETs / subnets / IP addresses. So for example an internal VM could access a service behind TCP LB via https://ep0.eth0.vr. This especially makes a lot of sense for OneFlow services which can be instantiated multiple times requiring minimal configuration.

CONTEXT VARIABLES		LOCAL-ZONE DOMAINS
ETH0_IP	ONEAPP_VROUTER_ETH0_VIP0	ip0.eth0.vr	vip0.eth0.vr	ep0.eth0.vr
10.11.12.13/24	10.11.12.254/24	10.11.12.13	10.11.12.254	10.11.12.254
10.11.12.13/24	undefined	10.11.12.13	undefined	10.11.12.13
undefined	10.11.12.254/24	undefined	10.11.12.254	10.11.12.254
undefined	undefined	undefined	undefined	undefined