use image from gitlab Registry in CI

Question

Could you tell me if I do it in correct way:

• I have create Docker image with all stuff which is need for running my tests in gitlab CI
• I push it to gitlab registry
• I can see on gitlab page in section Registry my image - gitlablogin/projectname
• I want to use this image for CI, so in .gitlab-ci.yml I add image: gitlablogin/projectname

Before I had had in .gitlab-ci.yml

same_task:
  stage: deploy
  image: python:3
  script:
    - python -V

Now I have:

pep8:
  stage: deploy
  image: gitlablogin/projectname
  script:
    - python -V

and after this change job failed:

Running with gitlab-runner 11.4.2 (cf91d5e1)
  on docker-auto-scale 72989761
Using Docker executor with image gitlablogin/projectname ...
Pulling docker image gitlablogin/projectname ...
ERROR: Job failed: Error response from daemon: pull access denied for gitlablogin/projectname, repository does not exist or may require 'docker login' (executor_docker.go:168:0s)

Is my usage of docker in context of gitlab CI and gitlab registry is correct? I also want to keep my docker file on same repo and build new image when samething change in Dockerfile, what will be the best way to do it?

Answer 1

Right now it is possible to use images from your gitlab registry without any special steps. Just build and push an image to your gitlab project container registry

docker build -t registry.gitlab.com/gitlabProject/projectName:build .
docker push registry.gitlab.com/gitlabProject/projectName:build 

and then just specify this image in your pipeline settings:

image: registry.gitlab.com/gitlabProject/projectName:build

Gitlab is able to pull this image using it's credentials:

Preparing the "docker+machine" executor
00:46
 Using Docker executor with image registry.gitlab.com/gitlabProject/projectName:build ...
 Authenticating with credentials from job payload (GitLab Registry)
 Pulling docker image registry.gitlab.com/gitlabProject/projectName:build ...
 Using docker image sha256:e7e0f4f5fa8cff8a93b1f37ffd7dd0505946648246aa921dd457c06a1607304b for registry.gitlab.com/gitlabProject/projectName:build ...

More: https://docs.gitlab.com/runner/configuration/advanced-configuration.html#using-a-private-container-registry