Adding Entrypoint

Updated Feb 05, 2023 ·

Overview

You can add --entrypoints.web.address in your Docker Compose file to have explicit control over the web entrypoint. This makes your setup more deterministic and configurable.

Sample docker-compose.yaml:

version: '3'

services:
  traefik:
    image: traefik:v2.3
    command:
      - --api.insecure=true       # Enables the Traefik Dashboard
      - --providers.docker=true
      - --log.level=INFO
      - "--entrypoints.web.address=:80"
    ports:
      - "80:80"                   # Exposes port 80 for incoming web requests
      - "8080:8080"               # The Web UI port http://0.0.0.0:8080
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

  whoami:
     image: containous/whoami
     labels:                      # Set hostname to the new service
       - "traefik.http.routers.whoami.rule=Host(`whoami.docker.localhost`)"

The line explicitly defines an entrypoint named web and bind it to port 80 on all network interfaces (: means all interfaces):

- "--entrypoints.web.address=:80"

If you add it:

• You can change the port if needed (e.g., :8080)

• Entrypoint can be used in:

  • labels (e.g., traefik.http.routers.myrouter.entrypoints=web)
  • Routing rules

If you don't add it:

• Traefik creates a default web entrypoint on port 80 only if it's not overridden elsewhere.

• But:

  • If you define custom entrypoints (e.g., websecure) and don’t define web, then web won't exist.
  • Routes relying on web might break or not be matched.

• It's less predictable if you don't declare it explicitly, especially in complex setups.

ports vs entrypoints

ports

In the same docker-compose.yml:

ports:
  - "80:80"
  - "8080:8080"

This means Docker maps:

• Host port 80 → Container port 80
• Host port 8080 → Container port 8080

It lets traffic reach the container, but it doesn’t tell Traefik what to do with those ports.

entrypoints

On the other hand:

`--entrypoints.web.address=:80

This tells Traefik to listen for HTTP traffic on port 80 inside the container and call that entrypoint web.

• Traefik uses this to define its internal routing logic.
• You can later reference web in your service/router labels.

Do You Need Both?

Yes, both serve different purposes:

Purpose	ports	--entrypoints.web.address=:80
Docker-level	Yes - Maps host to container port	No - Doesn't affect Docker port mapping
Traefik entrypoint definition	No - Does not affect Traefik's behavior directly	Yes - Defines how Traefik listens and labels ports
Needed for routing	No - just exposes port	Yes - Required for Traefik to know what web is