add a section in README for changing hub URL. Closes issue #1.

README.md

@@ -70,7 +70,33 @@ the `COMPOSE_PROJECT_NAME` that will serve as prefix to network name to separate
 
 File `docker-compose.yml` contains:
 ```yaml
-
+version: '3'
+
+services:
+  # Configuration for Hub+Proxy
+  jupyterhub:
+    image: ${COMPOSE_PROJECT_NAME}_hub_img
+    build: jupyterhub                # Build the container from this folder.
+    container_name: ${COMPOSE_PROJECT_NAME}_hub    # The service will use this container name.
+    volumes:                         # Give access to Docker socket.
+      - /var/run/docker.sock:/var/run/docker.sock
+      - ./jupyterhub/jupyterhub_config.py:/srv/jupyterhub/jupyterhub_config.py
+    environment:                     # Env variables passed to the Hub process.
+      DOCKER_JUPYTER_IMAGE: jupyter/minimal-notebook
+      DOCKER_NETWORK_NAME: ${COMPOSE_PROJECT_NAME}_default
+      HUB_IP: ${COMPOSE_PROJECT_NAME}_hub
+    ports:
+      - "8000:8000"
+
+  # Configuration for the single-user servers
+  jupyterlab:
+    image: jupyter/minimal-notebook
+    network_mode: none
+    command: echo
+
+networks:
+  default:
+     name: ${COMPOSE_PROJECT_NAME}_default
 ```
 
 ### Build and run
@@ -95,6 +121,57 @@ The following code should remove jupyterhub and user containers respectively.
 docker-compose down && docker rm $(docker ps -qa -f "name=jupyter-")
 ```
 
+### Change hub URL
+
+The the hub URL can be changed with `bind_url`. Example, if I want to route the hub to http://localhost/minimal_notebook
+instead of http://localhost:8000 I could do the following:
+```yaml
+# File docker-compose.yml
+version: '3'
+
+services:
+  # Configuration for Hub+Proxy
+  jupyterhub:
+    image: ${COMPOSE_PROJECT_NAME}_hub_img
+    build: jupyterhub                # Build the container from this folder.
+    container_name: ${COMPOSE_PROJECT_NAME}_hub    # The service will use this container name.
+    volumes:                         # Give access to Docker socket.
+      - /var/run/docker.sock:/var/run/docker.sock
+      - ./jupyterhub/jupyterhub_config.py:/srv/jupyterhub/jupyterhub_config.py
+    environment:                     # Env variables passed to the Hub process.
+      DOCKER_JUPYTER_IMAGE: jupyter/minimal-notebook
+      DOCKER_NETWORK_NAME: ${COMPOSE_PROJECT_NAME}_default
+      HUB_IP: ${COMPOSE_PROJECT_NAME}_hub
+      COMPOSE_PROJECT_NAME: ${COMPOSE_PROJECT_NAME}
+    ports:
+      - "80:80"
+
+  # Configuration for the single-user servers
+  jupyterlab:
+    image: jupyter/minimal-notebook
+    network_mode: none
+    command: echo
+
+networks:
+  default:
+     name: ${COMPOSE_PROJECT_NAME}_default
+```
+
+```python
+# jupyterhub_config.yml
+c = get_config()
+
+import os
+c.JupyterHub.spawner_class = 'dockerspawner.DockerSpawner'
+c.DockerSpawner.image = os.environ['DOCKER_JUPYTER_IMAGE']
+c.DockerSpawner.network_name = os.environ['DOCKER_NETWORK_NAME']
+c.JupyterHub.hub_ip = os.environ['HUB_IP']
+c.JupyterHub.bind_url = 'http://0.0.0.0:80/'+os.environ['COMPOSE_PROJECT_NAME']
+```
+
+However, with the docker port binding `80:80`, it wouldn't be possible to run another hub in parallel (e.g. for another tutorial).
+Thus rerouting outside the container would be a better solution (to be documented).
+
 ## Rstudio
 
 An Rstudio-session can be launched from inside a jupyterlab session with
@@ -145,6 +222,7 @@ These variables are stored in .env file and called in jupyterhub_config.py.
 # Authors
 
 Florian de Boissieu
+Rémy Decoupes