Gitlab CI cannot pull image from private docker registry

Question

I'd like to create a Docker based Gitlab CI runner which pulls the docker images for the build from a private Docker Registry (v2). I cannot make the Gitlab Runner to pull the image from a local Registry, it tries to GET something from a /v1 API. I get the following error message:

ERROR: Build failed: Error while pulling image: Get http://registry:5000/v1/repositories/maven/images: dial tcp: lookup registry on 127.0.1.1:53: no such host

Here's a minimal example, using docker-compose and a web browser.

I have the following docker-compose.yml file:

version: "2"

services:
  gitlab:
    image: gitlab/gitlab-ce
    ports:
      - "22:22"
      - "8080:80"
    links:
      - registry:registry

  gitlab_runner:
    image: gitlab/gitlab-runner
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    links:
      - registry:registry
      - gitlab:gitlab

  registry:
    image: registry:2

After the first Gitlab login, I register the runner into the Gitlab instance:

root@130d08732613:/# gitlab-runner register
Running in system-mode.                            

Please enter the gitlab-ci coordinator URL (e.g. https://gitlab.com/ci):
http://192.168.61.237:8080/ci         
Please enter the gitlab-ci token for this runner:
tE_1RKnwkfj2HfHCcrZW
Please enter the gitlab-ci description for this runner:
[130d08732613]: docker
Please enter the gitlab-ci tags for this runner (comma separated):

Registering runner... succeeded                     runner=tE_1RKnw
Please enter the executor: docker-ssh+machine, docker, docker-ssh, parallels, shell, ssh, virtualbox, docker+machine:
docker
Please enter the default Docker image (eg. ruby:2.1):
maven:latest
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!

After this, I see the Gitlab runner in my Gitlab instance:

After this I push a simple maven image to my newly created Docker repository:

vilmosnagy@vnagy-dell:~/$ docker tag maven:3-jdk-7 172.19.0.2:5000/maven:3-jdk7
vilmosnagy@vnagy-dell:~/$ docker push 172.19.0.2:5000/maven:3-jdk7 
The push refers to a repository [172.19.0.2:5000/maven]
79ab7e0adb89: Pushed 
f831784a6a81: Pushed 
b5fc1e09eaa7: Pushed 
446c0d4b63e5: Pushed 
338cb8e0e9ed: Pushed 
d1c800db26c7: Pushed 
42755cf4ee95: Pushed 
3-jdk7: digest: sha256:135e7324ccfc7a360c7641ae20719b068f257647231d037960ae5c4ead0c3771 size: 1794

(I got the 172.19.0.2 IP-address from a docker inspect command's output)

After this I create a test project in the Gitlab and add a simple .gitlab-ci.yml file:

image: registry:5000/maven:3-jdk-7

stages:
  - build
  - test
  - analyze

maven_build:
  stage: build
  script:
    - "mvn -version"

And after the build the Gitlab gives the error in seen in the beginning of the post.

If I enter into the running gitlab-runner container, I can access the registry under the given URL:

vilmosnagy@vnagy-dell:~/$ docker exec -it comptest_gitlab_runner_1 bash
root@c0c5cebcc06f:/# curl http://registry:5000/v2/maven/tags/list
{"name":"maven","tags":["3-jdk7"]}
root@c0c5cebcc06f:/# exit
exit
vilmosnagy@vnagy-dell:~/$

But the error still the same:

Do you have any idea how to force the gitlab-runner to use the v2 api of the private registry?

Answer 1

Current Gitlab and Gitlab Runners support this, see: https://docs.gitlab.com/runner/configuration/advanced-configuration.html#use-a-private-container-registry

On older Gitlab I've solved this with copying an auth key into ~/.docker/config.json

{
        "auths": {
                "my.docker.registry.url": {
                        "auth": "dmlsbW9zLm5hZ3k6VGZWNTM2WmhC"
                }
        }
}

I've logged into this container from my computer and copied this auth key into the Gitlab Runner's docker container.