play kube: service container

Add the notion of a "service container" to play kube.  A service
container is started before the pods in play kube and is (reverse)
linked to them.  The service container is stopped/removed *after*
all pods it is associated with are stopped/removed.

In other words, a service container tracks the entire life cycle
of a service started via `podman play kube`.  This is required to
enable `play kube` in a systemd unit file.

The service container is only used when the `--service-container`
flag is set on the CLI.  This flag has been marked as hidden as it
is not meant to be used outside the context of `play kube`.  It is
further not supported on the remote client.

The wiring with systemd will be done in a later commit.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

1 files changed, 37 insertions, 1 deletions

diff --git a/libpod/options.go b/libpod/options.go
index 9b83cb76a..feb89510f 100644
--- a/libpod/options.go
+++ b/libpod/options.go
@@ -1,6 +1,7 @@
 package libpod
 
 import (
+	"fmt"
 	"net"
 	"os"
 	"path/filepath"
@@ -1477,7 +1478,7 @@ func WithCreateCommand(cmd []string) CtrCreateOption {
 	}
 }
 
-// withIsInfra allows us to dfferentiate between infra containers and regular containers
+// withIsInfra allows us to dfferentiate between infra containers and other containers
 // within the container config
 func withIsInfra() CtrCreateOption {
 	return func(ctr *Container) error {
@@ -1491,6 +1492,20 @@ func withIsInfra() CtrCreateOption {
 	}
 }
 
+// WithIsService allows us to dfferentiate between service containers and other container
+// within the container config
+func WithIsService() CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+
+		ctr.config.IsService = true
+
+		return nil
+	}
+}
+
 // WithCreateWorkingDir tells Podman to create the container's working directory
 // if it does not exist.
 func WithCreateWorkingDir() CtrCreateOption {
@@ -2081,6 +2096,27 @@ func WithInfraContainer() PodCreateOption {
 	}
 }
 
+// WithServiceContainer associates the specified service container ID with the pod.
+func WithServiceContainer(id string) PodCreateOption {
+	return func(pod *Pod) error {
+		if pod.valid {
+			return define.ErrPodFinalized
+		}
+
+		ctr, err := pod.runtime.LookupContainer(id)
+		if err != nil {
+			return fmt.Errorf("looking up service container: %w", err)
+		}
+
+		if err := ctr.addServicePodLocked(pod.ID()); err != nil {
+			return fmt.Errorf("associating service container %s with pod %s: %w", id, pod.ID(), err)
+		}
+
+		pod.config.ServiceContainerID = id
+		return nil
+	}
+}
+
 // WithVolatile sets the volatile flag for the container storage.
 // The option can potentially cause data loss when used on a container that must survive a machine reboot.
 func WithVolatile() CtrCreateOption {