How to have a mirror repository on GitLab without the premium

In this article, I will explain an idea to have a semi-mirror repoistory feature without a premium version from GitLab as the mirror with pull mode is a premium

What is a mirror repository feature first?

If you have for example a codebase on a repository on GitHub or azure-DevOps and you want to have a mirror on GitLab to use for example the GitLab CI/CD feature or to have a backup repository and so on. GitLab offers a mirror repository feature with pull/push mode but only push available as free also the CI/CD repository is a premium.

We can make a very simple step to have this a simulation for this feature by writing a GitLab pipeline to do this using the following steps

• Create a new empty GitLab project
• Add a new .gitlab-ci.yml (GitLab CI) with the following content

stages:
- mirror-from-external
mirror-from-external:
stage: mirror-from-external
image: ubuntu:18.04
before_script:
- apt-get update -y && apt-get install openssh-client -y
- apt install git -y
- eval $(ssh-agent -s)
- echo "$GIT_SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
- mkdir -p ~/.ssh
- chmod 700 ~/.ssh
- ssh-keyscan $GIT_LAB_HOST >> ~/.ssh/known_hosts
- chmod 644 ~/.ssh/known_hosts
- git config --global user.name "${GIT_USER_NAME}"
- git config --global user.email "${GIT_USER_EMAIL}"
- ssh "git@$GIT_LAB_HOST"
script:
- echo $SOURCE_REPOSITORY
- git clone --mirror $SOURCE_REPOSITORY Your_Repo_folder_name
- cd Your_Repo_folder_name
- git remote remove origin
- git remote add origin $DESTINATION_REPOSITORY
- git push --prune --all
- git push --prune --tags
only:
- branches

Explanation :

We just use an ubuntu image with ssh and git then we cloned from the source repository and remove the remote origin then add the GitLab repository as a remote origin then push all and tags with prune to delete the deleted branches and tags

so now we have our pipeline and every time trigger this pipeline will take a snapshot from the source repository to the GitLab repository.

You can add a CI scheduler to trigger the pipeline automatically just go to CI/CD and choose the schedule option and create a new schedule.

Also, you can add a git hook in your source repository in your local machine to trigger the pipeline every push on your source repository by using GitLab API to do this

• Go to Settings >> CI/CD and at the end expand the Pipeline triggers accordion and click add a trigger

Then we have an API to trigger our pipeline

• Go to your .git\hooks on the source repository path on your development machine and create a new hook file with the name “pre-push” with the following content

#!/bin/sh
curl -X POST -F token=84accae6178539643a7177de83d552 -F ref=master https://your-git-lab-url/api/v4/projects/{projectID}/trigger/pipeline

Just replace the URL with your API URL as explained on the trigger

After that, every git push command will trigger the mirror pipeline to work that will take a snapshot from the source repository to the GitLab repository and that is all.

I hope that I helped you thanks.