Add support for podman --remote

[dustinblack]

Please describe what you would like to see in this project

Podman has the ability to run containers on a remote system via a socket connected to over ssh. We would like the ability to utilize this feature with both the default deployer and within a plugin step.

Please describe your use case

Running workflow plugins on target remote systems provides flexibility to include non-k8s remote targets, which would be helpful for CI execution as well as for parallelization of workflows across multiple targets.

Additional context

The server-side prerequisite for this is for the remote target host to enable the socket:

systemctl [--user] --now enable podman.socket

You can validate this is working on the server side with:

podman --remote info

On the client side (from where the workflow is run), an ssh identity for connection authentication with the remote host is required.

From the client, the remote connection is setup with:

podman system connection add <connection_name> --identity <path_to_ssh_private_key> ssh://<user>@<remote_host>/run/user/<uid>/podman/podman.sock

This connection can be validated on the client side with:

podman system connection list
podman --connection <connection_name> info

Once the remote connection is established and validated, a podman command can be run as usual, adding only --connection <connection_name> to the parameters (before the run command), for example:

podman --connection <connection_name> run -i --rm quay.io/arcalot/arcaflow-plugin-example:latest --schema