Application Load Balancing with Traefik
=======================================

Traefik dynamically discovers services running in Docker and routes traffic to them using simple container labels. This enables easy and powerful HTTP routing and load balancing without manual configuration.

In order for Traefik to recognize a container and route traffic to it, the container must be started with a specific set of labels.

Example Configuration
---------------------

Below is an example set of labels for a container that should be exposed via Traefik:

.. list-table:: Container Labels for Traefik
   :widths: 50 50
   :header-rows: 1

   * - Label
     - Value
   * - `traefik.enable`
     - `true`
   * - `traefik.http.routers.my_app.entrypoints`
     - `http`
   * - `traefik.http.routers.my_app.rule`
     - `Host(\`application.local\`)`
   * - `traefik.http.routers.my_app.service`
     - `my_app`
   * - `traefik.http.services.my_app.loadbalancer.server.port`
     - `80`

Label Breakdown
---------------

- **`traefik.enable=true`**  
  Enables Traefik for this container. If `false` or not set, Traefik will ignore it.

- **`traefik.http.routers.my_app.entrypoints=http`**  
  Binds this route to the `http` entry point (typically port 80).

- **`traefik.http.routers.my_app.rule=Host(\`application.local\`)`**  
  Defines the routing rule. In this case, any request with the Host header `application.local` will be routed to this container.

- **`traefik.http.routers.my_app.service=my_app`**  
  Assigns the router to a named service (here, `my_app`).

- **`traefik.http.services.my_app.loadbalancer.server.port=80`**  
  Defines the internal container port that Traefik should forward traffic to.

Usage
-----

To use this setup, ensure your Docker container is started with these labels (e.g., in `docker-compose.yml`):

.. code-block:: yaml

   services:
     my_app:
       image: my_app_image
       labels:
         - "traefik.enable=true"
         - "traefik.http.routers.my_app.entrypoints=http"
         - "traefik.http.routers.my_app.rule=Host(`application.local`)"
         - "traefik.http.routers.my_app.service=my_app"
         - "traefik.http.services.my_app.loadbalancer.server.port=80"

With this configuration, Traefik will automatically detect the container and route incoming HTTP requests with the host `application.local` to it.

This also enables built-in **load balancing**: if multiple containers share the same service name (`my_app`), Traefik will distribute requests between them.