[wanda] add podman backend

adds podman backend via podman_cmd. Requires
having podman already installed + available via PATH

I still need to battletest this, but this is the
general shape!

Topic: add-podman-backend
Relative: refactor-for-podman

Signed-off-by: andrew <andrew@anyscale.com>

Author: andrew-anyscale

wanda/container_cmd.go

@@ -82,9 +82,9 @@ func (c *baseContainerCmd) inspectImage(tag string) (*imageInfo, error) {
 	cmd.Stdout = buf
 	if err := cmd.Run(); err != nil {
 		if exitErr, ok := err.(*exec.ExitError); ok {
-			// Docker returns 1
+			// Docker returns 1, podman returns 125 for "image not found".
 			code := exitErr.ExitCode()
-			if code == 1 {
+			if code == 1 || code == 125 {
 				return nil, nil
 			}
 		}

wanda/container_cmd_test.go

@@ -33,7 +33,8 @@ func dockerAvailable() bool {
 }
 
 func podmanAvailable() bool {
-	return false
+	_, err := exec.LookPath("podman")
+	return err == nil
 }
 
 var containerRuntimes = []containerRuntimeTest{

wanda/forge_config.go

@@ -40,6 +40,11 @@ type ForgeConfig struct {
 
 // newContainerCmd creates a ContainerCmd based on the config settings.
 func (c *ForgeConfig) newContainerCmd() ContainerCmd {
+	if c.ContainerRuntime == RuntimePodman {
+		return NewPodmanCmd(&PodmanCmdConfig{
+			Bin: c.ContainerBin,
+		})
+	}
 	return NewDockerCmd(&DockerCmdConfig{
 		Bin:             c.ContainerBin,
 		UseLegacyEngine: runtime.GOOS == "windows",

wanda/podman_cmd.go

@@ -0,0 +1,49 @@
+package wanda
+
+import (
+	"fmt"
+	"os"
+)
+
+func podmanCmdEnvs() []string {
+	var envs []string
+	for _, k := range []string{
+		"HOME",
+		"USER",
+		"PATH",
+		"XDG_RUNTIME_DIR",
+		"CONTAINERS_CONF",
+		"REGISTRY_AUTH_FILE",
+	} {
+		if v, ok := os.LookupEnv(k); ok {
+			envs = append(envs, fmt.Sprintf("%s=%s", k, v))
+		}
+	}
+	return envs
+}
+
+// podmanCmd wraps the podman CLI for building container images.
+type podmanCmd struct {
+	baseContainerCmd
+}
+
+// PodmanCmdConfig configures the podman command.
+type PodmanCmdConfig struct {
+	Bin string
+}
+
+// NewPodmanCmd creates a new podman container command.
+func NewPodmanCmd(config *PodmanCmdConfig) ContainerCmd {
+	bin := config.Bin
+	if bin == "" {
+		bin = "podman"
+	}
+	envs := podmanCmdEnvs()
+
+	return &podmanCmd{
+		baseContainerCmd: baseContainerCmd{
+			bin:  bin,
+			envs: envs,
+		},
+	}
+}

wanda/podman_cmd_test.go

@@ -0,0 +1,23 @@
+package wanda
+
+import (
+	"testing"
+)
+
+func TestNewPodmanCmd(t *testing.T) {
+	c := NewPodmanCmd(&PodmanCmdConfig{})
+	cmd := c.(*podmanCmd)
+
+	if cmd.bin != "podman" {
+		t.Errorf("bin: got %q, want %q", cmd.bin, "podman")
+	}
+}
+
+func TestNewPodmanCmd_customBin(t *testing.T) {
+	c := NewPodmanCmd(&PodmanCmdConfig{Bin: "/usr/local/bin/podman"})
+	cmd := c.(*podmanCmd)
+
+	if cmd.bin != "/usr/local/bin/podman" {
+		t.Errorf("bin: got %q, want %q", cmd.bin, "/usr/local/bin/podman")
+	}
+}

wanda/wanda/main.go

@@ -27,6 +27,7 @@ Flags:
 func main() {
 	workDir := flag.String("work_dir", ".", "root directory for the build")
 	dockerBin := flag.String("docker", "", "path to the docker/podman binary")
+	podman := flag.Bool("podman", false, "use podman instead of docker")
 	rayCI := flag.Bool(
 		"rayci", false,
 		"takes RAYCI_ env vars for input and run in remote mode",
@@ -73,6 +74,9 @@ func main() {
 
 	// Determine the container runtime.
 	runtime := wanda.RuntimeDocker
+	if *podman {
+		runtime = wanda.RuntimePodman
+	}
 
 	config := &wanda.ForgeConfig{
 		WorkDir:    *workDir,