Add Service Discovery option for non-Swarm Docker (#316)

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.20 as builder
+FROM golang:1.22 AS builder
 
 WORKDIR /build
 

README.md

@@ -22,12 +22,16 @@ Routes Minecraft client connections to backend servers based upon the requested
         Enable debug logs (env DEBUG)
   -default string
         host:port of a default Minecraft server to use when mapping not found (env DEFAULT)
+  -docker-socket
+        Path to Docker socket to use (env DOCKER_SOCKET) (default "unix:///var/run/docker.sock")
   -docker-refresh-interval int
         Refresh interval in seconds for the Docker Swarm integration (env DOCKER_REFRESH_INTERVAL) (default 15)
   -docker-timeout int
         Timeout configuration in seconds for the Docker Swarm integration (env DOCKER_TIMEOUT)
+  -in-docker
+        Use Docker service discovery (env IN_DOCKER)
   -in-docker-swarm
-        Use in-swarm Docker config (env IN_DOCKER_SWARM)
+        Use Docker Swarm service discovery (env IN_DOCKER_SWARM)
   -in-kube-cluster
         Use in-cluster Kubernetes config (env IN_KUBE_CLUSTER)
   -kube-config string
@@ -114,6 +118,33 @@ To test out this example, add these two entries to my "hosts" file:
 127.0.0.1 forge.example.com
 ```
 
+### Using Docker auto-discovery
+
+When running `mc-router` in a Docker environment you can pass the `--in-docker` or `--in-docker-swarm` 
+command-line argument and it will poll the Docker API periodically to find all the running
+containers/services for Minecraft instances. To enable discovery you have to set the `mc-router.host`
+label on the container. These are the labels scanned:
+
+- `mc-router.host`: Used to configure the hostname the Minecraft clients would use to 
+  connect to the server. The container/service endpoint will be used as the routed backend. You can 
+  use more than one hostname by splitting it with a comma.
+- `mc-router.port`: This value must be set to the port the Minecraft server is listening on.
+  The default value is 25565.
+- `mc-router.default`: Set this to a truthy value to make this server the default backend.
+  Please note that `mc-router.host` is still required to be set.
+- `mc-router.network`: Specify the network you are using for the router if multiple are 
+  present in the container/service. You can either use the network ID, it's full name or an alias.
+
+#### Example Docker deployment
+
+Refer to [this example docker-compose.yml](docs/sd-docker.docker-compose.yml) to see how to
+configure two different Minecraft servers and a `mc-router` instance for use with Docker service discovery.
+
+#### Example Docker Swarm deployment
+
+Refer to [this example docker-compose.yml](docs/swarm.docker-compose.yml) to see how to
+configure two different Minecraft servers and a `mc-router` instance for use with Docker Swarm service discovery.
+
 ## Routing Configuration
 
 The routing configuration allows routing via a config file rather than a command. 
@@ -213,32 +244,6 @@ rules:
   verbs: ["watch","list","get","update"]
 ```
 
-## Docker Swarm Usage
-
-### Using Docker Swarm Service auto-discovery
-
-When running `mc-router` in a Docker Swarm environment you can pass the `--in-docker-swarm` 
-command-line argument and it will poll the Docker API periodically to find all the running
-services for minecraft instances. To enable discovery you have to set the `mc-router.host`
-label on the service. These are the labels scanned:
-
-- `mc-router.host`: Used to configure the hostname the Minecraft clients would use to 
-  connect to the server. The service endpoint will be used as the routed backend. You can 
-  use more than one hostname by splitting it with a comma.
-- `mc-router.port`: This value must be set to the port the Minecraft server is listening on.
-  The default value is 25565.
-- `mc-router.default`: Set this to a truthy value to make this server the deafult backend.
-  Please note that `mc-router.host` is still required to be set.
-- `mc-router.network`: Specify the network you are using for the router if multiple are 
-  present in the service. You can either use the network ID, it's full name or an alias.
-
-### Example Docker Swarm deployment
-
-Refer to [this example docker-compose.yml](docs/swarm.docker-compose.yml) to see how to
-configure two different Minecraft servers and a `mc-router` instance. Notice how you don't 
-have to expose the Minecraft instances ports, but all the containers are required to be in
-the same network.
-
 ## REST API
 
 * `GET /routes` (with `Accept: application/json`)
@@ -365,4 +370,4 @@ docker run -it --rm \
 
 ## Related Projects
 
-* https://github.com/haveachin/infrared
+* https://github.com/haveachin/infrared

cmd/mc-router/main.go

@@ -40,9 +40,11 @@ type Config struct {
 	InKubeCluster         bool              `usage:"Use in-cluster Kubernetes config"`
 	KubeConfig            string            `usage:"The path to a Kubernetes configuration file"`
 	AutoScaleUp           bool              `usage:"Increase Kubernetes StatefulSet Replicas (only) from 0 to 1 on respective backend servers when accessed"`
-	InDockerSwarm         bool              `usage:"Use in-swarm Docker config"`
-	DockerTimeout         int               `default:"0" usage:"Timeout configuration in seconds for the Docker Swarm integration"`
-	DockerRefreshInterval int               `default:"15" usage:"Refresh interval in seconds for the Docker Swarm integration"`
+	InDocker              bool              `usage:"Use Docker service discovery"`
+	InDockerSwarm         bool              `usage:"Use Docker Swarm service discovery"`
+	DockerSocket          string            `default:"unix:///var/run/docker.sock" usage:"Path to Docker socket to use"`
+	DockerTimeout         int               `default:"0" usage:"Timeout configuration in seconds for the Docker integrations"`
+	DockerRefreshInterval int               `default:"15" usage:"Refresh interval in seconds for the Docker integrations"`
 	MetricsBackend        string            `default:"discard" usage:"Backend to use for metrics exposure/publishing: discard,expvar,influxdb"`
 	UseProxyProtocol      bool              `default:"false" usage:"Send PROXY protocol to backend servers"`
 	ReceiveProxyProtocol  bool              `default:"false" usage:"Receive PROXY protocol from backend servers, by default trusts every proxy header that it receives, combine with -trusted-proxies to specify a list of trusted proxies"`
@@ -161,12 +163,21 @@ func main() {
 		}
 	}
 
+	if config.InDocker {
+		err = server.DockerWatcher.Start(config.DockerSocket, config.DockerTimeout, config.DockerRefreshInterval)
+		if err != nil {
+			logrus.WithError(err).Fatal("Unable to start docker integration")
+		} else {
+			defer server.DockerWatcher.Stop()
+		}
+	}
+
 	if config.InDockerSwarm {
-		err = server.DockerWatcher.StartInSwarm(config.DockerTimeout, config.DockerRefreshInterval)
+		err = server.DockerSwarmWatcher.Start(config.DockerSocket, config.DockerTimeout, config.DockerRefreshInterval)
 		if err != nil {
 			logrus.WithError(err).Fatal("Unable to start docker swarm integration")
 		} else {
-			defer server.DockerWatcher.Stop()
+			defer server.DockerSwarmWatcher.Stop()
 		}
 	}
 

docs/sd-docker.docker-compose.yml

@@ -0,0 +1,34 @@
+services:
+  mcfoo:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      MOTD: "foo"
+    volumes:
+      - mcfoodata:/data
+    labels:
+      mc-router.host: "foo.localhost"
+      mc-router.default: true
+  mcbar:
+    image: itzg/minecraft-server
+    environment:
+      EULA: "TRUE"
+      MOTD: "bar"
+    volumes:
+      - mcbardata:/data
+    labels:
+      mc-router.host: "bar.localhost"
+  router:
+    image: itzg/mc-router:latest
+    command: "-debug -in-docker"
+    depends_on:
+      - mcfoo
+      - mcbar
+    ports:
+      - "25565:25565"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+
+volumes:
+  mcfoodata:
+  mcbardata: