Docker – Connect GitLab and Gitlab runner, both in Docker

dockergitlab

How can I connect my GitLab installation with a runner, that are both running in separate docker containers?

GitLab is working fine, it is reachable via http://docker.lcnet:8181

My first problem is, where can I find my Gitlab "CI" URL? or is it just my normal URL? Do I have to inlcude the Port?

I'm using this doc:
https://docs.gitlab.com/ce/ci/docker/using_docker_images.html

This is what I get:

ubuntu@docker:~$ sudo docker exec -it gitlab-runner gitlab-runner register

Running in system-mode.

Please enter the gitlab-ci coordinator URL (e.g. https://gitlab.com/):
http://docker.lcnet:8181
Please enter the gitlab-ci token for this runner:
<token from settings>
Please enter the gitlab-ci description for this runner:
[5bf3c5086904]: my-runner
Please enter the gitlab-ci tags for this runner (comma separated):
tag1
ERROR: Registering runner... failed runner=hm-eFuar status=couldn't execute POST against http://docker.lcnet:8181/ci/api/v1/runners/register.json:                                                                      Post http://docker.lcnet:8181/ci/api/v1/runners/register.json: dial tcp: lookup vader.nts on 8.8.8.8:53: no such host
PANIC: Failed to register this runner. Perhaps you are having network problems

I see that there are network problems but after some hours of searching I couldn't find a decent hint to resolve this problem.
I know that docker images can communicate with each other via docker-names but this isn't mentioned anywhere how to set this up.

I tried to enter "gitlab-ce" (which is the name of the docker container running gitlab) but it won't work.

Do I have to create a docker network?

Best Answer

Ok so after diving into docker more deeply, I understood that I have to link the runner-container to the GitLab container with "link".

This is something that is missing in the docs above. Although it says that running Gitlab and a runner on the same machine isn't suggested (which I guess would also solve the problem), in some scenarios it is needed, so it would be nice to mention that the containers have to be linked:

$ docker run -d -P --name gitlabce gitlab/gitlab-ce:latest
$ docker run -d -P --name runner --link gitlabce:gitlabce gitlab/gitlab-runner:latest

$ docker exec -it runner gitlab-runner register
Running in system-mode.                                                                                                                                                                                                                                       

Please enter the gitlab-ci coordinator URL (e.g. https://gitlab.com/):                                                                                                                                                                                        
http://gitlabce  

Please enter the gitlab-ci token for this runner:                                                                                                                                                                                                             
(your token from gitlab->admin->runner) 

Please enter the gitlab-ci description for this runner:                                                                                                                                                                                                       
[a11fa3f389d9]:    

Please enter the gitlab-ci tags for this runner (comma separated):                                                                                                                                                                                            

Registering runner... succeeded

I'm new to docker so sorry for this trivial question, but maybe it will help others.

Another method would be to create a user defined network, since, if I understood correctly, containers can communicate with each other without links.

Related Solutions

Docker – how to set the image volume in gitlab-runner with docker executor

The answer is... it clones to the build directory in the image, by creating the directory and then cloning to it, much like calling docker exec. So when you are running commands you are running them in the build container, that containers image is set with the 'image:' key. So in order to get scripts from the host system into the build container, you will have to set the volume from the host to the build container. So I put an extra directory in my image, I called it tools_for_ci, then I mount a directory with all those scripts to the image. This works great. The issue now arises, that the docker image can not talk back and forth with the services. This is a known hindrance with docker executor, with no improvement in site, all the issues I have seen are marked backlog. So unfortunately it does not look like a fix will be implemented for that any time soon.

So in short, the image gets all the files it needs from the repo at run time, which means you do not need to set a volume, unless you are transferring scripts from the host to the image. All script commands are also executed on the image.

However, docker in docker, when binded to the docker socket, does appear to save the images so you don't have to re-download every time. So I may try that to get around the issue with the back and forth communication between the image and the services.

Docker – gitlab-runner process in container can’t find gitlab container when using docker-compose

So, since I have come across this issue myself, I thought I would reply here with my fix and an explanation:

My home lab has git-lab docker setup, and I use docker-compose to deploy both the gitlab and gitlab-runner servers. What this does is create a network that links the two together, allowing for hostname recognition within the containers...but not from outside of the created network.

Gitlab-runner, I have found by default will startup a container when running a test and add it to the "bridge" docker network. If you use dockstation you can see this by checking the info of the created container before it stops, or run docker inspect against it: docker inspect --format='{{.NetworkSettings.Networks}}' <runner temp container_id>

I had another container running on bridge and tested whether 'gitlab' would resolve. It would not.

Soooooooo.....there is a setting you can pass in the gitlab-runner's config.toml:

[[runners]]
...
  [runners.docker]
    network_mode= <----- THIS

This setting will tell gitlab-runner which network to place the container in when it gets spun up, so if you know the name of the network your gitlab and gitlab-containers run on:

docker inspect --format='{{.NetworkSettings.Networks}}' <gitlab container id>

then add that as the network mode (my network name is git-lab_default):

[[runners]]
...
  [runners.docker]
    network mode= "git-lab_default"

Then voila! Your test containers will be in the same network and everything is peachy.

Hope this helps anyone with the issue.

Best Answer

Related Solutions

Docker – how to set the image volume in gitlab-runner with docker executor

Docker – gitlab-runner process in container can’t find gitlab container when using docker-compose

Related Topic