feat: add filtering by container label for Docker integration (#194)

app/server/config/integration/docker.ts

@@ -6,6 +6,11 @@ import log from '~/utils/log';
 import type { HeadplaneConfig } from '../schema';
 import { Integration } from './abstract';
 
+interface DockerContainer {
+	Id: string;
+	Names: string[];
+}
+
 type T = NonNullable<HeadplaneConfig['integration']>['docker'];
 export default class DockerIntegration extends Integration<T> {
 	private maxAttempts = 10;
@@ -15,13 +20,63 @@ export default class DockerIntegration extends Integration<T> {
 		return 'Docker';
 	}
 
+	async getContainerName(label: string, value: string): Promise<string> {
+		if (!this.client) {
+			throw new Error('Docker client is not initialized');
+		}
+
+		const filters = encodeURIComponent(
+			JSON.stringify({
+				label: [`${label}=${value}`],
+			}),
+		);
+		const { body } = await this.client.request({
+			method: 'GET',
+			path: `/containers/json?filters=${filters}`,
+		});
+		const containers: DockerContainer[] =
+			(await body.json()) as DockerContainer[];
+		if (containers.length > 1) {
+			throw new Error(
+				`Found multiple Docker containers matching label ${label}=${value}. Please specify a container name.`,
+			);
+		}
+		if (containers.length === 0) {
+			throw new Error(
+				`No Docker containers found matching label: ${label}=${value}`,
+			);
+		}
+		log.info(
+			'config',
+			'Found Docker container matching label: %s=%s',
+			label,
+			value,
+		);
+		return containers[0].Id;
+	}
+
 	async isAvailable() {
-		if (this.context.container_name.length === 0) {
+		// Perform a basic check to see if any of the required properties are set
-			log.error('config', 'Docker container name is empty');
+		if (
+			this.context.container_name.length === 0 &&
+			!this.context.container_label
+		) {
+			log.error('config', 'Docker container name and label are both empty');
 			return false;
 		}
 
-		log.info('config', 'Using container: %s', this.context.container_name);
+		if (
+			this.context.container_name.length > 0 &&
+			!this.context.container_label
+		) {
+			log.error(
+				'config',
+				'Docker container name and label are mutually exclusive',
+			);
+			return false;
+		}
+
+		// Verify that Docker socket is reachable
 		let url: URL | undefined;
 		try {
 			url = new URL(this.context.socket);
@@ -72,6 +127,38 @@ export default class DockerIntegration extends Integration<T> {
 				socketPath: url.pathname,
 			});
 		}
+		if (this.client === undefined) {
+			log.error('config', 'Failed to create Docker client');
+			return false;
+		}
+
+		if (this.context.container_name.length === 0) {
+			try {
+				if (this.context.container_label === undefined) {
+					log.error('config', 'Docker container label is not defined');
+					return false;
+				}
+				const containerName = await this.getContainerName(
+					this.context.container_label.name,
+					this.context.container_label.value,
+				);
+				if (containerName.length === 0) {
+					log.error(
+						'config',
+						'No Docker containers found matching label: %s=%s',
+						this.context.container_label.name,
+						this.context.container_label.value,
+					);
+					return false;
+				}
+				this.context.container_name = containerName;
+			} catch (error) {
+				log.error('config', 'Failed to get Docker container name: %s', error);
+				return false;
+			}
+		}
+
+		log.info('config', 'Using container: %s', this.context.container_name);
 
 		return this.client !== undefined;
 	}

app/server/config/schema.ts

@@ -41,10 +41,16 @@ const headscaleConfig = type({
 	config_strict: stringToBool,
 }).onDeepUndeclaredKey('reject');
 
+const containerLabel = type({
+	name: 'string',
+	value: 'string',
+}).optional();
+
 const dockerConfig = type({
 	enabled: stringToBool,
 	container_name: 'string',
 	socket: 'string = "unix:///var/run/docker.sock"',
+	container_label: containerLabel,
 });
 
 const kubernetesConfig = type({

compose.yaml

@@ -10,6 +10,8 @@ services:
   headscale:
     image: "headscale/headscale:0.25.1"
     container_name: "headscale"
+    labels:
+      - com.headplane.selector=headscale
     restart: "unless-stopped"
     command: "serve"
     networks:

config.example.yaml

@@ -47,8 +47,14 @@ headscale:
 integration:
   docker:
     enabled: false
-    # The name (or ID) of the container running Headscale
+    # Preferred method: use container_label to dynamically discover the Headscale container.
-    container_name: "headscale"
+    container_label:
+      name: "com.headplane.selector"
+      value: "headscale"
+    # Optional fallback: directly specify the container name (or ID)
+    # of the container running Headscale
+    # container_name: "headscale"
+
     # The path to the Docker socket (do not change this if you are unsure)
     # Docker socket paths must start with unix:// or tcp:// and at the moment
     # https connections are not supported.

docs/Integrated-Mode.md

@@ -70,11 +70,14 @@ you build the container yourself or run Headplane in Bare-Metal mode.
 > setting up your `config.yaml` file to the appropriate values.
 
 ## Docker Integration
-The Docker integration is the easiest to setup, as it only requires the Docker socket
+The Docker integration is the easiest to set up, as it only requires mounting the
-to be mounted into the container along with some configuration. As long as Headplane
+Docker socket into the container along with some basic configuration. Headplane
-has access to the Docker socket and the name of the Headscale container, it will
+uses Docker labels to discover the Headscale container. As long as Headplane has
-automatically propagate config and DNS changes to Headscale without any additional
+access to the Docker socket and can identify the Headscale container—either by
-configuration.
+label or name—it will automatically propagate configuration and DNS changes to
+Headscale without any additional setup. Alternatively, instead of using a label
+to dynamically determine the container name, it is possible to directly specify
+the container name.
 
 ## Native Linux (/proc) Integration
 The `proc` integration is used when you are running Headscale and Headplane on