add the ability to set aliases per network

README.md

@@ -106,6 +106,25 @@ labels:
 > A network named `frontend` in a project folder `myapp` becomes
 > `myapp_frontend`.
 
+### Network aliases
+
+If a container has the label `traefik.aliases` these aliases are set for
+traefik when it is added to the network. `traefik.aliases` must be a
+comma-separated list. Having aliases on traefik is useful to separate stacks
+but still letting a container from one stack talk through traefik to the other
+stack.
+
+```yaml
+labels:
+  - "traefik.enable=true"
+  - "traefik.aliases=myotherapp.domain"
+  - "traefik.docker.network=myapp_frontend"
+  - "traefik.http.routers.myapp.rule=Host(`myapp.${DOMAIN}`)"
+  - "traefik.http.routers.myapp.entrypoints=websecure"
+  - "traefik.http.routers.myapp.tls.certresolver=letsencrypt"
+  - "traefik.http.services.myapp.loadbalancer.server.port=8080"
+```
+
 ---
 
 ## ⚙️ Configuration

main.py

@@ -106,7 +106,11 @@ def connect_traefik_to_network(container):
     # Retrieve allowed networks from the container's labels, if specified
     allowed_networks_label = container.labels.get(config.traefik.networkLabel, "")
     allowed_networks = allowed_networks_label.split(",")
-
+
+    # add alias labels
+    alias_label = container.labels.get("traefik.aliases")
+    aliases = [a.strip() for a in alias_label.split(",") if a.strip()] if alias_label else []
+
     app_logger.debug(f"Allowed networks: {allowed_networks}")
 
     for net in target_networks:
@@ -130,7 +134,10 @@ def connect_traefik_to_network(container):
         if allowed_networks == [''] or net in allowed_networks:
             if net not in traefik_container.attrs["NetworkSettings"]["Networks"]:
                 app_logger.debug(f"Connecting Traefik to network {net}.")
-                network.connect(traefik_container)
+                if aliases and net in allowed_networks:
+                    network.connect(traefik_container, aliases=aliases)
+                else:
+                    network.connect(traefik_container)
                 app_logger.info(f"Successfully connected Traefik to network {net}.")
             else:
                 app_logger.info(f"Traefik is already connected to network {net}, skipping connection.")

tests/unit/test_main_logic.py

@@ -251,6 +251,113 @@ def test_compose_network_resolution(self, mock_docker_client, mock_config, mock_
 
         network.connect.assert_called_once_with(traefik)
 
+    def test_no_alias_set(self, mock_docker_client, mock_config, mock_logger):
+        """
+        When traefik.aliases is not set, the container should not get an alias
+        """
+        container = MagicMock()
+        container.name = "web-app"
+        container.attrs = {
+            "NetworkSettings": {"Networks": {"app_net": {}}}
+        }
+        container.labels = {}
+
+        traefik = MagicMock()
+        traefik.attrs = {"NetworkSettings": {"Networks": {"bridge": {}}}}
+        mock_docker_client.containers.get.return_value = traefik
+
+        network = MagicMock()
+        network.attrs = {"Name": "app_net", "Labels": {}}
+        mock_docker_client.networks.get.return_value = network
+
+        main.connect_traefik_to_network(container)
+
+        network.connect.assert_called_once()
+        assert("aliases" not in network.connect.call_args.kwargs.keys())
+
+    def test_single_alias_set(self, mock_docker_client, mock_config, mock_logger):
+        """
+        When traefik.aliases is set to a single value, the network connect call
+        should have that value as alias
+        """
+        container = MagicMock()
+        container.name = "web-app"
+        container.attrs = {
+            "NetworkSettings": {"Networks": {"app_net": {}}}
+        }
+        container.labels = {
+            "traefik.aliases": "app",
+            "traefik.docker.network": "app_net",
+        }
+
+        traefik = MagicMock()
+        traefik.attrs = {"NetworkSettings": {"Networks": {"bridge": {}}}}
+        mock_docker_client.containers.get.return_value = traefik
+
+        network = MagicMock()
+        network.attrs = {"Name": "app_net", "Labels": {}}
+        mock_docker_client.networks.get.return_value = network
+
+        main.connect_traefik_to_network(container)
+
+        network.connect.assert_called_once_with(traefik, aliases=["app"])
+
+    def test_multiple_aliases_set(self, mock_docker_client, mock_config, mock_logger):
+        """
+        When traefik.aliases is set to a comma separated string, the network
+        connect call should have a list of strings value as aliases value
+        """
+        container = MagicMock()
+        container.name = "web-app"
+        container.attrs = {
+            "NetworkSettings": {"Networks": {"app_net": {}}}
+        }
+        container.labels = {
+            "traefik.aliases": "app, app2, app3",
+            "traefik.docker.network": "app_net",
+        }
+
+        traefik = MagicMock()
+        traefik.attrs = {"NetworkSettings": {"Networks": {"bridge": {}}}}
+        mock_docker_client.containers.get.return_value = traefik
+
+        network = MagicMock()
+        network.attrs = {"Name": "app_net", "Labels": {}}
+        mock_docker_client.networks.get.return_value = network
+
+        main.connect_traefik_to_network(container)
+
+        network.connect.assert_called_once_with(
+            traefik, aliases=["app", "app2", "app3"])
+
+    def test_aliases_with_additional_whitespace(self, mock_docker_client, mock_config, mock_logger):
+        """
+        When traefik.aliases is set to a comma separated string, the network
+        connect call should have a list of strings value as aliases value
+        """
+        container = MagicMock()
+        container.name = "web-app"
+        container.attrs = {
+            "NetworkSettings": {"Networks": {"app_net": {}}}
+        }
+        container.labels = {
+            "traefik.aliases": " app one, app2, app3   ",
+            "traefik.docker.network": "app_net",
+        }
+
+        traefik = MagicMock()
+        traefik.attrs = {"NetworkSettings": {"Networks": {"bridge": {}}}}
+        mock_docker_client.containers.get.return_value = traefik
+
+        network = MagicMock()
+        network.attrs = {"Name": "app_net", "Labels": {}}
+        mock_docker_client.networks.get.return_value = network
+
+        main.connect_traefik_to_network(container)
+
+        network.connect.assert_called_once_with(
+            traefik, aliases=["app one", "app2", "app3"])
+
 
 # ---------------------------------------------------------------------------
 # disconnect_traefik_from_network
@@ -462,3 +569,4 @@ def get_container(name):
 
         # connect should have been called for both containers' networks
         assert network.connect.call_count == 2
+