setup ~/.ssh using cloudflared access service token and installs cloudflared

TODO / limitations

• assumes sshd is on port 22
• only works for a single remote machine jumping through a bastion
• assumes bastion and remote machine use the same user
• assumes private key is encrypted
• only works for linux
• installs hardcoded version(s) or the latest from the stable channel

usage

- uses: gnawhleinad/setup-cloudflared-ssh@v0.0.4
  with:
    # cloudflared --version (default: stable)
    cloudflared-version: stable

    # cloudflared access service token id
    cloudflared-service-token-id:

    # cloudflared access service token secret
    cloudflared-service-token-secret:

    # ssh bastion hostname (cloudflared access hostname)
    ssh-bastion:

    # contents of ~/.ssh/known_hosts (appended)
    ssh-known-hosts:

    # contents of ~/.ssh/{encrypted-key}
    ssh-private-key:

    # passphrase for ~/.ssh/{encrypted-key}
    ssh-passphrase:

    # ssh hostname
    ssh-hostname:

~/.ssh/config

Host {{ssh-bastion}}
        HostName {{ssh-bastion}}
        Port 22
        IdentityFile ~/.ssh/{{ssh-private-key}}
        ProxyCommand cloudflared access ssh --id {{cloudflared-service-token-id}} --secret {{cloudflared-service-token-secret}} --hostname %h

Host {{ssh-hostname}}
        HostName {{ssh-hostname}}
        Port 22
        IdentityFile ~/.ssh/{{ssh-private-key}}
        ProxyJump %r@{{ssh-bastion}}

see dist/setup-ssh.sh for more details