Introduce podman machine os commands

Introduce machine os and machine os apply. Note that these are both stubs at the current moment, and do not introduce functionality. In order to build them, you must use the `experimental` build tag, or use `make podman-remote-experimental`

[NO NEW TESTS NEEDED]
as there is no actual functionality and this is a WIP.

Signed-off-by: Ashley Cui <acui@redhat.com>

Makefile

@@ -385,6 +385,15 @@ bin/rootlessport: $(SOURCES) go.mod go.sum
 .PHONY: rootlessport
 rootlessport: bin/rootlessport
 
+.PHONY: podman-remote-experimental
+podman-remote-experimental: $(SRCBINDIR)/experimental/podman$(BINSFX)
+$(SRCBINDIR)/experimental/podman$(BINSFX): $(SOURCES) go.mod go.sum | $(SRCBINDIR)
+	$(GOCMD) build \
+		$(BUILDFLAGS) \
+		$(GO_LDFLAGS) '$(LDFLAGS_PODMAN)' \
+		-tags "${REMOTETAGS} experimental" \
+		-o $@ ./cmd/podman
+
 ###
 ### Secondary binary-build targets
 ###

cmd/podman/machine/os.go

@@ -0,0 +1,28 @@
+//go:build (amd64 || arm64) && experimental
+// +build amd64 arm64
+// +build experimental
+
+package machine
+
+import (
+	"github.com/containers/podman/v4/cmd/podman/registry"
+	"github.com/containers/podman/v4/cmd/podman/validate"
+	"github.com/spf13/cobra"
+)
+
+var (
+	OSCmd = &cobra.Command{
+		Use:               "os",
+		Short:             "Manage a virtual machine's os",
+		Long:              "Manage a virtual machine's operating system",
+		PersistentPreRunE: validate.NoOp,
+		RunE:              validate.SubCommandExists,
+	}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Command: OSCmd,
+		Parent:  machineCmd,
+	})
+}

cmd/podman/machine/os/apply.go

@@ -0,0 +1,38 @@
+//go:build (amd64 || arm64) && experimental
+// +build amd64 arm64
+// +build experimental
+
+package machineos
+
+import (
+	"fmt"
+
+	"github.com/containers/podman/v4/cmd/podman/machine"
+	"github.com/containers/podman/v4/cmd/podman/registry"
+	"github.com/containers/podman/v4/cmd/podman/validate"
+	"github.com/spf13/cobra"
+)
+
+var (
+	applyCmd = &cobra.Command{
+		Use:               "apply",
+		Short:             "Apply OCI image to existing VM",
+		Long:              "Apply custom layers from a containerized Fedora CoreOS image on top of an existing VM",
+		PersistentPreRunE: validate.NoOp,
+		RunE:              apply,
+		Example:           `podman machine os apply myimage`,
+	}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Command: applyCmd,
+		Parent:  machine.OSCmd,
+	})
+
+}
+
+func apply(cmd *cobra.Command, args []string) error {
+	fmt.Println("Applying..")
+	return nil
+}

cmd/podman/main_experimental.go

@@ -0,0 +1,8 @@
+//go:build experimental
+// +build experimental
+
+package main
+
+import (
+	_ "github.com/containers/podman/v4/cmd/podman/machine/os"
+)