Docker provider does not detect exposed port

Traefik Traefik v3 (latest)
1

Hello :slight_smile:

I'm new to Traefik, going through the Docker Quick Start: Docker and Traefik Quick Start - Traefik .

What did you do?

When trying to test my setup, I get a 404:

❯ curl http://whoami.localhost
404 page not found

The Traefik service logged an error when I started the Whoami service:

traefik-1  | 2026-02-12T11:09:56Z ERR error="service \"whoami-traefik\" error: port is missing" container=whoami-traefik-a8ad089214719afa6565adcddb17b1c74b99f22147a4c497397c54bcf6ed8488 providerName=docker

According to the documentation for the Docker provider ( Traefik Docker Documentation - Traefik ): "If a container exposes a single port, then Traefik uses this port."

The traefok/whoami:latest image (as of now, latest is v1.11) does expose port 80:

❯ docker inspect --format='{{.Config.ExposedPorts}}' traefik/whoami:latest
map[80/tcp:{}]

I managed to fix my issue by adding this label to the Whoami service: "traefik.http.services.whoami.loadbalancer.server.port=80".

I am not sure if this is a Docker or a Traefik issue.

What did you see instead?

I expected Traefik to detect the port exposed by the Whoami service, and not have to add a label to the Whoami service.

What version of Traefik are you using?

The image is traefik:v3.6.

❯ docker run traefik:v3.6 version
Version:      3.6.8
Codename:     ramequin
Go version:   go1.25.7
Built:        2026-02-11T16:35:44Z
OS/Arch:      linux/arm64

What is your environment & configuration?

❯ docker --version
Docker version 28.3.0, build 38b7060

❯ uname -a
Darwin L437 24.6.0 Darwin Kernel Version 24.6.0: Wed Nov  5 21:28:03 PST 2025; root:xnu-11417.140.69.705.2~1/RELEASE_ARM64_T8122 arm64

Do you have any idea what is happening? Thank you!

2

This is a community forum, users supporting users.

If you think this is a bug, you better check with the devs at Traefik Github.

3

Hi! I was told to post here :frowning: Docker provider does not detect exposed port · Issue #12661 · traefik/traefik · GitHub

EDIT: I do think it is a bug, but I have no experience with Traefik so maybe something with my setup is wrong.

4

Ok, it works for me on latest Debian, latest Docker, latest Traefik, even when removing port label (simple Traefik example).

How do you run Docker on Mac? Via Docker Desktop? Because usually a VM is created to run Linux containers, so there is some extra isolation.

5

Ok, I updated Docker Desktop (and so docker) to the latest version, and now it works :slight_smile:.

❯ docker --version
Docker version 29.2.0, build 0b9d198

I quickly skimmed through Docker Engine and Desktop release notes to find out why, without success… Anyway, thank you!

6

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