Alpine SSH Client Docker Image

This is a minimal Alpine image based on alpine:latest that embeds an SSH client.

Useful within CI/CD pipelines when it's necessary to SSH into a server.

Use Github version of this repo (instead of Gitlab) because of automatic Build trigger from Docker Hub

Push to both Gitlab (origin) and Github (github_build)

Update Image upon new Alpine version by manually triggering a build in Docker Hub build tab

Usage in terminal

docker pull altdsoy/alpine-ssh
docker run --rm -it --env SSH_PRIVATE_KEY=abcd altdsoy/alpine-ssh

Usage in a CI/CD pipeline

• Set the SSH_PRIVATE_KEY environment with the SSH private key within you CI/CD environment
• Use the image in your scripts: image: altdsoy/alpine-ssh
• You can now SSH into your server in following scripts: ssh user@example.com 'ls -alh'

Example with Gitlab

#.gitlab-ci.yml
deploy_job:
  image: altdsoy/alpine-ssh
  script:
    - ssh example.com 'rm -rf ~/project && mkdir -p ~/project'
    - scp -r ./project example.com:~/project/
    - ssh example.com 'docker-compose up -d'

Usage with overriding the default environment variable

In case the name of the SSH Private Key environemnt variable name is already set, it's possible to use another name.

Just echo the environment variable into ~/ssh_key (set as the IdentityFile in ssh config)

Example with Gitlab

#.gitlab-ci.yml
deploy_job:
  image: altdsoy/alpine-ssh
  script:
    - echo "$CUSTOM_SERVER_SSH" > ~/ssh_key
    - ssh example.com 'rm -rf ~/project && mkdir -p ~/project'
    - scp -r ./project example.com:~/project/
    - ssh example.com 'docker-compose up -d'

Generating SSH key pair dedicated to the CI/CD server

Generate a key pair in any computer

Here the pair is named id_ed25519 and id_ed25519.pub and it's generated in the current directory:

ssh-keygen -o -a 128 -t ed25519 -f ./id_ed25519 -C "gitlab-ci"

Copying the Public key to the server

This will add the public key to the server.

Regular SSH login/password might be required here.

ssh-copy-id -f ./id_ed25519 user@example.com

Copying the Private Key to the CI/CD server

⚠️ The private key must not be shared in any case.

Nor be in any version controlled file.

Use the GUI of your CI/CD tool or any other way to securely set the environment variable SSH_PRIVATE_KEY in yout CI/CD environment.

In Gitlab, go under: Settings (on the left) > CI / CD > Variables (Expand) > Add Variable