fix: Podman compose incorrectly targets docker engine w/ compose

[muchzill4]

Changes

ℹ️ This seems to affect podman 4.9.x, which is the version ubuntu 24.04 LTS ship with, my local tests with brewed podman 6.0.0 did work as expected w/o explicit DOCKER_HOST being set

• Configure the docker-compose provider with Podman’s resolved local API endpoint via DOCKER_HOST.
• Keep raw Podman commands on their normal local configuration; use CONTAINER_HOST only for explicit sockets.
• Correct deployment assertions to query containers with raw Podman rather than Compose, preventing tests from checking Docker while Podman Compose was misconfigured.
  • See the CI failure from the first commit of this PR
• Cache the resolved local Compose endpoint

Checklist

• 🤖 This change is covered by tests as required.
• 🤹 All required manual testing has been performed.
• 📖 All documentation updates are complete.

[th3james]

Functionally looks OK, but there are a few tweaks to consider

[th3james]

Overwriting this seems a touch invasive and could let to subtle misbehaviour. Possible that I'm being paranoid, but is it worth respecting the existing value?

Suggested change

	runtime_dir="$RUNNER_TEMP/podman-runtime"
	mkdir -p "$runtime_dir/podman"
	chmod 700 "$runtime_dir"
	echo "XDG_RUNTIME_DIR=$runtime_dir" >> "$GITHUB_ENV"
	export XDG_RUNTIME_DIR="$runtime_dir"
	runtime_dir="${XDG_RUNTIME_DIR:-$RUNNER_TEMP/podman-runtime}"
	mkdir -p "$runtime_dir/podman"
	if [ -z "${XDG_RUNTIME_DIR:-}" ]; then
	chmod 700 "$runtime_dir"
	echo "XDG_RUNTIME_DIR=$runtime_dir" >> "$GITHUB_ENV"
	export XDG_RUNTIME_DIR="$runtime_dir"
	fi

[th3james]

Found this quite hard to follow, I think it's clearer if we separate out "get the URL from a Socket" from "change the ENV"

Suggested change

	func (socket Socket) ConfigureComposeEnv(environment []string) ([]string, error) {
	if socket.localComposeSocket == nil {
	return append(environment, "DOCKER_HOST="+socket.url), nil
	}
	return socket.localComposeSocket.ConfigureEnv(environment)
	}
	func (socket *localComposeSocket) ConfigureEnv(environment []string) ([]string, error) {
	socket.mutex.Lock()
	defer socket.mutex.Unlock()
	if socket.url == "" {
	url, err := ResolveLocalComposeSocket(context.Background())
	if err != nil {
	return nil, err
	}
	socket.url = url
	}
	return append(environment, "DOCKER_HOST="+socket.url), nil
	}
	func (socket Socket) ConfigureComposeEnv(environment []string) ([]string, error) {
	socketURL, err := socket.GetSocketURL()
	if err != nil {
	return nil, err
	}
	return append(environment, "DOCKER_HOST="+socketURL), nil
	}
	func (socket Socket) GetSocketURL() (string, error) {
	if socket.localComposeSocket != nil {
	return socket.localComposeSocket.GetSocketURL()
	}
	if socket.url == "" {
	return "", errors.New("podman socket URL not configured")
	}
	return socket.url, nil
	}
	func (socket *localComposeSocket) GetSocketURL() (string, error) {
	socket.mutex.Lock()
	defer socket.mutex.Unlock()
	if socket.url == "" {
	url, err := ResolveLocalComposeSocket(context.Background())
	if err != nil {
	return "", err
	}
	socket.url = url
	}
	return socket.url, nil
	}

[th3james]

This is on the public interface and it takes a context, but it has a single call site inside this package , and the only context it gets passed is context.Background().
Should we consider either removing the ability to pass a context, or update the function APIs up the call stack to allow passing the existing context down?