coredns-docker-discovery/setup.go

package dockerdiscovery

import (
	"strconv"

	"github.com/coredns/coredns/core/dnsserver"
	"github.com/coredns/coredns/plugin"

	dockerapi "github.com/fsouza/go-dockerclient"

	"github.com/coredns/caddy"
)

const defaultDockerEndpoint = "unix:///var/run/docker.sock"
const defaultDockerDomain = "docker.local"

func init() {
	caddy.RegisterPlugin("docker", caddy.Plugin{
		ServerType: "dns",
		Action:     setup,
	})
}

// TODO(kevinjqiu): add docker endpoint verification
func createPlugin(c *caddy.Controller) (*DockerDiscovery, error) {
	dd := NewDockerDiscovery(defaultDockerEndpoint)
	labelResolver := &LabelResolver{hostLabel: "coredns.dockerdiscovery.host"}
	dd.resolvers = append(dd.resolvers, labelResolver)

	for c.Next() {
		args := c.RemainingArgs()
		if len(args) == 1 {
			dd.dockerEndpoint = args[0]
		}

		if len(args) > 1 {
			return dd, c.ArgErr()
		}

		for c.NextBlock() {
			var value = c.Val()
			switch value {
			case "domain":
				var resolver = &SubDomainContainerNameResolver{
					domain: defaultDockerDomain,
				}
				dd.resolvers = append(dd.resolvers, resolver)
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				resolver.domain = c.Val()
			case "hostname_domain":
				var resolver = &SubDomainHostResolver{
					domain: defaultDockerDomain,
				}
				dd.resolvers = append(dd.resolvers, resolver)
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				resolver.domain = c.Val()
			case "compose_domain":
				var resolver = &ComposeResolver{
					domain: defaultDockerDomain,
				}
				dd.resolvers = append(dd.resolvers, resolver)
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				resolver.domain = c.Val()
			case "network_aliases":
				var resolver = &NetworkAliasesResolver{
					network: "",
				}
				dd.resolvers = append(dd.resolvers, resolver)
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				resolver.network = c.Val()
			case "filter_network":
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				dd.filterNetwork = c.Val()
			case "label":
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				labelResolver.hostLabel = c.Val()
			case "ttl":
				if !c.NextArg() {
					return dd, c.ArgErr()
				}
				ttl, err := strconv.ParseUint(c.Val(), 10, 32)
				if err != nil {
					return dd, err
				}
				if ttl > 0 {
					dd.ttl = uint32(ttl)
				}
			default:
				return dd, c.Errf("unknown property: '%s'", c.Val())
			}
		}
	}
	dockerClient, err := dockerapi.NewClient(dd.dockerEndpoint)
	if err != nil {
		return dd, err
	}
	dd.dockerClient = dockerClient
	go dd.start()
	return dd, nil
}

func setup(c *caddy.Controller) error {
	dd, err := createPlugin(c)
	if err != nil {
		return err
	}

	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
		dd.Next = next
		return dd
	})
	return nil
}