1. Set up SSH Keys for Authentication

To enable secure authentication between GitLab and your remote server, you need to generate SSH keys.

a. Generate SSH Key Pair

If you haven't already, generate an SSH key pair on your local machine using the following command:

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Press Enter to accept the default file location, then enter a passphrase if desired.

b. Add the SSH Private Key to GitLab

Once you've generated the SSH key, add the private key to your GitLab CI/CD variables:

• Go to Settings > CI / CD > Variables in your GitLab project.
• Create a new variable:
• Key: SSH_PRIVATE_KEY
• Value: Paste the contents of your private key file (e.g., ~/.ssh/id_rsa).
• Type: Variable

c. Add the SSH Public Key to Your Server

Copy your SSH public key (~/.ssh/id_rsa.pub) to the remote server's authorized keys:

ssh-copy-id -i ~/.ssh/id_rsa.pub user@your-server

This will enable GitLab CI to authenticate with the server over SSH.

2. Configure .gitlab-ci.yml for Deployment

Now, create the .gitlab-ci.yml file at the root of your repository to define the CI/CD pipeline for deployment.

Here’s an example of the .gitlab-ci.yml file:

stages:
  - deploy

deploy:
  stage: deploy
  script:
    - echo "Deploying PHP code via SSH"
    - mkdir -p ~/.ssh
    - echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config
    - eval $(ssh-agent -s)
    - echo "$SSH_PRIVATE_KEY" | tr -d '\r' | ssh-add -
    - ssh user@your-server "cd /path/to/deploy && git pull"
        

3. Test the CI/CD Pipeline

Once you've added the .gitlab-ci.yml file to your repository, GitLab will automatically detect the file and run the CI/CD pipeline when you push the changes. Check the pipeline logs to ensure that the SSH deployment works correctly.

4. Security Considerations

• Private Key Handling: Make sure the private key is securely stored in GitLab CI/CD variables and never exposed in logs or the repository.
• StrictHostKeyChecking: Disabling strict host key checking is often safe in a controlled environment (CI/CD), but in production, ensure proper host key verification is enabled.