pod create: add --infra-conmon-pidfile

Add an `--infra-conmon-pidfile` flag to `podman-pod-create` to write the
infra container's conmon process ID to a specified path.  Several
container sub-commands already support `--conmon-pidfile` which is
especially helpful to allow for systemd to access and track the conmon
processes.  This allows for easily tracking the conmon process of a
pod's infra container.

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

cmd/podman/pods/create.go

@@ -53,6 +53,7 @@ func init() {
 	flags.AddFlagSet(common.GetNetFlags())
 	flags.StringVar(&createOptions.CGroupParent, "cgroup-parent", "", "Set parent cgroup for the pod")
 	flags.BoolVar(&createOptions.Infra, "infra", true, "Create an infra container associated with the pod to share namespaces with")
+	flags.StringVar(&createOptions.InfraConmonPidFile, "infra-conmon-pidfile", "", "Path to the file that will receive the POD of the infra container's conmon")
 	flags.StringVar(&createOptions.InfraImage, "infra-image", containerConfig.Engine.InfraImage, "The image of the infra container to associate with the pod")
 	flags.StringVar(&createOptions.InfraCommand, "infra-command", containerConfig.Engine.InfraCommand, "The command to run on the infra container when the pod is started")
 	flags.StringSliceVar(&labelFile, "label-file", []string{}, "Read in a line delimited file of labels")
@@ -83,6 +84,9 @@ func create(cmd *cobra.Command, args []string) error {
 
 	if !createOptions.Infra {
 		logrus.Debugf("Not creating an infra container")
+		if cmd.Flag("infra-conmon-pidfile").Changed {
+			return errors.New("cannot set infra-conmon-pid without an infra container")
+		}
 		if cmd.Flag("infra-command").Changed {
 			return errors.New("cannot set infra-command without an infra container")
 		}

completions/bash/podman

@@ -3098,6 +3098,7 @@ _podman_pod_create() {
       --dns-opt
       --dns-search
       --infra-command
+      --infra-conmon-pidfile
       --infra-image
       --ip
       --label-file

docs/source/markdown/podman-pod-create.1.md

@@ -47,6 +47,10 @@ Set a hostname to the pod
 
 Create an infra container and associate it with the pod. An infra container is a lightweight container used to coordinate the shared kernel namespace of a pod. Default: true.
 
+**--infra-conmon-pidfile**=*file*
+
+Write the pid of the infra container's **conmon** process to a file. As **conmon** runs in a separate process than Podman, this is necessary when using systemd to manage Podman containers and pods.
+
 **--infra-command**=*command*
 
 The command that will be run to start the infra container. Default: "/pause".

libpod/options.go

@@ -1550,6 +1550,18 @@ func WithPodCreateCommand() PodCreateOption {
 	}
 }
 
+// WithInfraConmonPidFile sets the path to a custom conmon PID file for the
+// infra container.
+func WithInfraConmonPidFile(path string) PodCreateOption {
+	return func(pod *Pod) error {
+		if pod.valid {
+			return define.ErrPodFinalized
+		}
+		pod.config.InfraContainer.ConmonPidFile = path
+		return nil
+	}
+}
+
 // WithPodLabels sets the labels of a pod.
 func WithPodLabels(labels map[string]string) PodCreateOption {
 	return func(pod *Pod) error {

libpod/pod.go

@@ -83,6 +83,7 @@ type podState struct {
 
 // InfraContainerConfig is the configuration for the pod's infra container
 type InfraContainerConfig struct {
+	ConmonPidFile      string               `json:"conmonPidFile"`
 	HasInfraContainer  bool                 `json:"makeInfraContainer"`
 	HostNetwork        bool                 `json:"infraHostNetwork,omitempty"`
 	PortBindings       []ocicni.PortMapping `json:"infraPortBindings"`

libpod/runtime_pod_infra_linux.go

@@ -130,6 +130,9 @@ func (r *Runtime) makeInfraContainer(ctx context.Context, p *Pod, imgName, rawIm
 	options = append(options, WithRootFSFromImage(imgID, imgName, rawImageName))
 	options = append(options, WithName(containerName))
 	options = append(options, withIsInfra())
+	if len(p.config.InfraContainer.ConmonPidFile) > 0 {
+		options = append(options, WithConmonPidFile(p.config.InfraContainer.ConmonPidFile))
+	}
 
 	return r.newContainer(ctx, g.Config, options...)
 }

pkg/domain/entities/pods.go

@@ -108,6 +108,7 @@ type PodCreateOptions struct {
 	Infra              bool
 	InfraImage         string
 	InfraCommand       string
+	InfraConmonPidFile string
 	Labels             map[string]string
 	Name               string
 	Net                *NetOptions
@@ -127,6 +128,9 @@ func (p PodCreateOptions) ToPodSpecGen(s *specgen.PodSpecGenerator) {
 	if len(p.InfraCommand) > 0 {
 		s.InfraCommand = strings.Split(p.InfraCommand, " ")
 	}
+	if len(p.InfraConmonPidFile) > 0 {
+		s.InfraConmonPidFile = p.InfraConmonPidFile
+	}
 	s.InfraImage = p.InfraImage
 	s.SharedNamespaces = p.Share
 

pkg/specgen/generate/pod_create.go

@@ -94,5 +94,8 @@ func createPodOptions(p *specgen.PodSpecGenerator) ([]libpod.PodCreateOption, er
 	}
 	options = append(options, libpod.WithPodCgroups())
 	options = append(options, libpod.WithPodCreateCommand())
+	if len(p.InfraConmonPidFile) > 0 {
+		options = append(options, libpod.WithInfraConmonPidFile(p.InfraConmonPidFile))
+	}
 	return options, nil
 }

pkg/specgen/podspecgen.go

@@ -25,6 +25,9 @@ type PodBasicConfig struct {
 	// InfraCommand and InfraImages in this struct.
 	// Optional.
 	NoInfra bool `json:"no_infra,omitempty"`
+	// InfraConmonPidFile is a custom path to store the infra container's
+	// conmon PID.
+	InfraConmonPidFile string `json:"infra_conmon_pid_file,omitempty"`
 	// InfraCommand sets the command that will be used to start the infra
 	// container.
 	// If not set, the default set in the Libpod configuration file will be

test/e2e/pod_start_test.go

@@ -193,4 +193,23 @@ var _ = Describe("Podman pod start", func() {
 		Expect(session.ExitCode()).To(Equal(0))
 		Expect(podmanTest.NumberOfContainersRunning()).To(Equal(20)) // 10*(infra+top)
 	})
+
+	It("podman pod create --infra-conmon-pod create + start", func() {
+		tmpDir, err := ioutil.TempDir("", "")
+		Expect(err).To(BeNil())
+		tmpFile := tmpDir + "podID"
+		defer os.RemoveAll(tmpDir)
+
+		podName := "rudolph"
+		// Create a pod with --infra-conmon-pid.
+		session := podmanTest.Podman([]string{"pod", "create", "--name", podName, "--infra-conmon-pidfile", tmpFile})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+
+		session = podmanTest.Podman([]string{"pod", "start", podName})
+		session.WaitWithDefaultTimeout()
+		Expect(session.ExitCode()).To(Equal(0))
+		Expect(podmanTest.NumberOfContainersRunning()).To(Equal(1)) // infra
+	})
+
 })