Connect with open-sshd

This GitHub Action opens an SSH connection to the github actions runner through an intermediary server. It is intended to debug jobs through SSH.

Pre-requisites

The gateway server has to be accessible from internet. The gateway ssh server configuration (usually in /etc/ssh/sshd_config) needs the following configuration

AllowTcpForwarding yes
GatewayPorts yes

How to use

First add the action to your workflow.

  - name: Debug through SSH
    uses: edipizarro/runner-open-ssh @main
    with:
      sshPublicKey: ${{ secrets.SSH_PUBLIC_KEY }}
      gatewayPrivateKey: ${{ secrets.GATEWAY_PRIVATE_KEY }}
      gatewayIP: ${{ secrets.GATEWAY_IP }}
      maxLifeTime: 30

• sshPublicKey: Public SSH key that will be authorized in the github runner.
• gatewayPrivateKey: Private SSH Key that can access the Gateway server. The action will use this key to SSH to the gateway server and open a proxy on port 2222, consequently, the gateway server will be able to SSH with the runner.
• gatewayIP is the public IP of the gateway (used by the runner to ssh to the gateway)
• maxLifeTime is the maximum life of the connection in seconds. default value is 3600 (1 hour). When the action SSH's to the gateway, it runs "sleep ${maxLifeTime}".

After the job is run, the runner creates a proxy on the gateway on port 2222. So, to connect to the runner, first ssh to the gateway server, and from there run "ssh -p 2222 runner@localhost".

The ssh proxy connection is run as a background process (using the ampersand &). And to keep the action alive a tmux terminal is attached.

If you want to close the connection before the maxLifeTime (to continue to the next action or just to finish the job), execute 'tmux kill-session'. This will kill the tmux session and then the action will finish. You can also just cancel the action.