Start traefik with docker backend in circleCI 2.0 (after setup_remote_docker)

README.md

The issue

CircleCI uses a TCP endpoint (echo $DOCKER_HOST) and not the unix socket to communicate with the docker deamon (on another docker machine). Mounting volumes won't work: /var/run/docker.sock:/var/run/docker.sock fails. Source circleCI building-docker-images and circleCI docker-compose

Solution

Setup traefik with a TCP endpoint :

• You need to copy the certificats: cp -R $DOCKER_CERT_PATH ./circle-cert (after you ran - setup_remote_docker in you circle file)
• Then docker build -t traefik-ci Dockerfile (see the dockerfile next).
• You can run docker run --rm -p 80:80 --name traefik-reverse-proxy traefik-ci -l debug --docker --docker.endpoint=$DOCKER_HOST --docker.tls=true --docker.tls.ca=/cert/ca.pem --docker.tls.key=/cert/key.pem --docker.tls.cert=/cert/cert.pem --docker.tls.insecureskipverify=true .

Misc

Thanks to https://discuss.circleci.com/t/gcloud-docker-push-image/15040 and https://discuss.circleci.com/t/cannot-connect-to-the-docker-daemon-at-unix-var-run-docker-sock/12195 for the inspiration.

If something is wrong, say it here! Hope this helps.

Dockerfile

# Docker file used for traefik in CircleCI
FROM traefik

# Necessary because CircleCI use a tcp endpoint and not the unix socket.
# It requires certificats for TLS, and because CircleCI use docker machine,
# mounting a volume doesn't work.
# NB circle-cert needs to contain $DOCKER_CERT_PATH, see README.md
COPY circle-cert /cert

# if you used to share other volumes, you need to copy them now or with `docker cp`
# NB if you mount volumes in a docker-compose.yml file, they won't be mounted to the container but will
# make it fail if the volume they mount already exists (example here: /ssl or /traefik.toml)
# COPY ssl /ssl
# COPY traefik.ci.toml /traefik.toml

Thanks for this. I think I'm doing something wrong though as I still see it complaining about trying to connect to the daemon at http+docker://localhost - have you had to make any updates to this in the last two years?

We run traefik via a separate docker compose file called proxy.yml so I'm not sure how to pass the docker options to it this way.