docker:dind tries to listen to two overlapping ports

[nickygerritsen]

It seems that since 7db7ecc the docker:dind container listens on $DOCKER_HOST instead of unix:///var/run/docker.sock besides listening on 0.0.0.0 port 2375 or 2376.
However, for GitLab CI to work (in Kubernetes) we have to set the environment variable DOCKER_HOST to tcp://localhost:2375. This results in docker:dind trying to bind to 2375 twice (if DOCKER_TLS_CERTDIR="" which is needed for now to get stuff working until Gitlab offers an option to share the certdir), which gives a bind: address already in use error.

For now I have fixed this by setting DOCKER_HOST to tcp://localhost:2378, letting Docker use a port that is not in use yet, but it seems to me that this is not an ideal solution.

Note that it not only broke for docker:dind but also for other versions like docker:18-dind.

[alexandrujieanu]

My setup is using Gitlab CI with docker-dind (https://docs.gitlab.com/ce/ci/docker/using_docker_build.html#use-docker-in-docker-workflow-with-docker-executor), with

  DOCKER_DRIVER: overlay2
  DOCKER_HOST: tcp://docker:2375/

I tried switching the port to 2378, it didn't work.

It worked by removing the DOCKER_HOST variable.

[nickygerritsen]

Might be that the fix for port 2378 is specific to the Kubernetes runner :) .

[paolomainardi]

We are facing the same issue, as a result all our CI pipelines todays are broken, our quick fix for now is downgrade to docker:17-dind

[dc2tom]

I've confirmed that 18.09.7-dind fixes the issue for now. 18.09.8 is the problem tag. I wish I hadn't advised all of our teams to roll back to 18-dind and not the explicit version the other day :(

[jakubfijalkowski]

If someone is using v19 line, I can confirm that 19.03.0 also works.

[maresja1]

@dc2tom Fixing to specific version does not help - I advised our team to rollback from latest to 18.09.8-dind and it worked fine for a week. And guess what - this version was overwritten 4hrs ago. Unbelievable.

[prawana-perera]

If someone is using v19 line, I can confirm that 19.03.0 also works.

I tried 19.03-dind, this did not work, same issue

[peter-c-larsson]

The version to use is 19.03.0-dind since the 19.03.1-dind is the one failing and that is the same version as 19.03-dind

Getting used to look at the tag times here: https://hub.docker.com/_/docker?tab=tags

[paolomainardi]

19.03.0-dind is failing as well for the TLS thing on #176

[Eji4h]

If someone is using v19 line, I can confirm that 19.03.0 also works.

I tried 19.03-dind, this did not work, same issue

It work for me.

[azzaka]

Soooo.... essentially if we add:

variables:
DOCKER_DRIVER: overlay2
DOCKER_TLS_CERTDIR: ""

to the gitlab-ci file it will disable the TLS flag, and if we add:

variables:
DOCKER_DRIVER: overlay2
DOCKER_TLS_CERTDIR: "/certs"

It will enable the flag. Not tested it yet, hoping it will fix it.

[tmaczukin]

@azzaka From what I see, any of:

1. Remove DOCKER_HOST: tcp://docker/237x
2. Use strict version: docker:19.03.0-dind/docker:18.09.7-dind

should help.

The TLS problem was discussed last week, also in this issue tracker (#170). And at the end you can find a link to our blog post, that describes what happened and how TLS problem can be resolved: https://about.gitlab.com/2019/07/31/docker-in-docker-with-docker-19-dot-03/.

[tmaczukin]

I've proposed #177 as a solution for this issue.