Clone a GitLab git repository inside a Dockerfile/build run inside GitLab CI

GitLabCIGitRepoCloneDockerfile

# Add the following key to the 'Deploy Keys' section in Settings/Repository of your GitLab repository
# Dockerfile:
FROM centos:7

ARG SSH_KEY_GITLAB_DEPLOY_KEY

RUN \
    ### ssh configuration, see https://docs.gitlab.com/ee/ci/ssh_keys/#ssh-keys-when-using-the-docker-executor
    # run ssh-agent inside build environment
    eval $(ssh-agent -s); \
    # add ssh-key from GitLab variable to ssh agent store incl. fixing line endings
    echo "${SSH_KEY_GITLAB_DEPLOY_KEY}" | tr -d '\r' | ssh-add -; \
    # create the SSH directory and give it the right permissions
    mkdir -p ~/.ssh; \
    # Allow access to gitlab.your.lan
    echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config; \
    chmod 700 ~/.ssh; \
    \
    git clone ssh://git@gitlab.your.lan:2222/yourgroup/yourrepository.git;

# Run with docker build and include Deploy Key fully as build-arg
docker build . --force-rm --build-arg SSH_KEY_GITLAB_DEPLOY_KEY="-----BEGIN OPENSSH PRIVATE KEY-----
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