dnsname plugin

Overview

This plugin sets up the use of dnsmasq on a given CNI network so that Pods can resolve each other by name. When configured, the pod and its IP address are added to a network specific hosts file that dnsmasq reads in. Similarly, when a pod is removed from the network, it will remove the entry from the hosts file. Each CNI network will have its own dnsmasq instance.

The dnsname plugin was specifically designed for the Podman container engine. Follow the mini-tutorial to use it with Podman.

Usage

The dnsname plugin can be enabled in the cni network configuration file.

{
    "cniVersion": "0.4.0",
    "name": "cni-bridge-network",
    "plugins": [
      {
        "type": "bridge",
        "bridge": "cni0",
        ...
        }
      },
      {
        "type": "dnsname",
        "domainName": "foobar.com",
        "capabilities": {
            "aliases": true
        }
      }
    ]
}

DNSMasq configuration files

The dnsmasq service and its configuration files are considered to be very fluid and are not meant to survive a system reboot. Therefore, files are stored in /run/containers/cni/dnsname, or under $XDG_RUNTIME_DIR/containers/cni/dnsname if XDG_RUNTIME_DIR is specified. The plugin knows to recreate the necessary files if it detects they are not present.

DNSMasq default configuration

Much like the implementation of DNSMasq for libvirt, this plugin will only set up dnsmasq to listen on the network interfaces associated with the CNI network. The DNSMasq services are not configured or managed by systemd but rather only by the plugin itself.

Network aliases

The dnsname plugin is capable of not only adding the container name for DNS resolution but also adding network aliases. These aliases are also added to the DNSMasq host file.

Reporting issues

If you are using dnsname code compiled directly from github, then reporting bugs and problem to the dnsname github issues tracker is appropriate. In the case that you are using code compiled and provided by a Linux distribution, you should file the problem with their appropriate bug tracker (bugzilla/trackpad).