containers.conf: add pod_exit_policy

Add a new `pod_exit_policy` field to the containers.conf's engine table.
A pod's exit policy determines the behaviour when the last container of
a pod exits.

Required-in: containers/podman/pull/13859
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

common/docs/containers.conf.5.md

@@ -549,6 +549,15 @@ pod consumes one lock. The default number available is 2048. If this is
 changed, a lock renumbering must be performed, using the
 `podman system renumber` command.
 
+**pod_exit_policy**="continue"
+
+Set the exit policy of the pod when the last container exits.  Supported policies are:
+
+| Exit Policy        | Description                                                                 |
+| ------------------ | --------------------------------------------------------------------------- |
+| *continue*         | The pod continues running when the last container exits. Used by default.   |
+| *stop*             | The pod is stopped when the last container exits. Used in `play kube`.      |
+
 **pull_policy**="always"|"missing"|"never"
 
 Pull image before running or creating a container. The default is **missing**.

common/pkg/config/config.go

@@ -349,6 +349,9 @@ type EngineConfig struct {
 	// OCIRuntimes are the set of configured OCI runtimes (default is runc).
 	OCIRuntimes map[string][]string `toml:"runtimes,omitempty"`
 
+	// PodExitPolicy determines the behaviour when the last container of a pod exits.
+	PodExitPolicy PodExitPolicy `toml:"pod_exit_policy,omitempty"`
+
 	// PullPolicy determines whether to pull image before creating or running a container
 	// default is "missing"
 	PullPolicy string `toml:"pull_policy,omitempty"`

common/pkg/config/config_test.go

@@ -362,6 +362,7 @@ image_copy_tmp_dir="storage"`
 			}
 			gomega.Expect(config.Engine.EventsLogFilePath).To(gomega.BeEquivalentTo(config.Engine.TmpDir + "/events/events.log"))
 			gomega.Expect(uint64(config.Engine.EventsLogFileMaxSize)).To(gomega.Equal(DefaultEventsLogSizeMax))
+			gomega.Expect(config.Engine.PodExitPolicy).To(gomega.Equal(PodExitPolicyContinue))
 		})
 
 		It("should success with valid user file path", func() {
@@ -402,6 +403,7 @@ image_copy_tmp_dir="storage"`
 			gomega.Expect(err).To(gomega.BeNil())
 			gomega.Expect(path).To(gomega.BeEquivalentTo("/tmp/foobar"))
 			gomega.Expect(uint64(config.Engine.EventsLogFileMaxSize)).To(gomega.Equal(uint64(500)))
+			gomega.Expect(config.Engine.PodExitPolicy).To(gomega.BeEquivalentTo(PodExitPolicyStop))
 		})
 
 		It("should fail with invalid value", func() {

common/pkg/config/containers.conf

@@ -506,6 +506,9 @@ default_sysctls = [
 #
 #num_locks = 2048
 
+# Set the exit policy of the pod when the last container exits.
+#pod_exit_policy = "continue"
+
 # Whether to pull new image before running a container
 #
 #pull_policy = "missing"

common/pkg/config/default.go

@@ -388,6 +388,8 @@ func defaultConfigFromMemory() (*EngineConfig, error) {
 	c.MachineEnabled = false
 	c.ChownCopiedFiles = true
 
+	c.PodExitPolicy = defaultPodExitPolicy
+
 	return c, nil
 }
 

common/pkg/config/pod_exit_policy.go

@@ -0,0 +1,36 @@
+package config
+
+import "fmt"
+
+// PodExitPolicies includes the supported pod exit policies.
+var PodExitPolicies = []string{string(PodExitPolicyContinue), string(PodExitPolicyStop)}
+
+// PodExitPolicy determines a pod's exit and stop behaviour.
+type PodExitPolicy string
+
+const (
+	// PodExitPolicyContinue instructs the pod to continue running when the
+	// last container has exited.
+	PodExitPolicyContinue PodExitPolicy = "continue"
+	// PodExitPolicyStop instructs the pod to stop when the last container
+	// has exited.
+	PodExitPolicyStop = "stop"
+	// PodExitPolicyUnsupported implies an internal error.
+	// Negative for backwards compat.
+	PodExitPolicyUnsupported = "invalid"
+
+	defaultPodExitPolicy = PodExitPolicyContinue
+)
+
+// ParsePodExitPolicy parses the specified policy and returns an error if it is
+// invalid.
+func ParsePodExitPolicy(policy string) (PodExitPolicy, error) {
+	switch policy {
+	case "", string(PodExitPolicyContinue):
+		return PodExitPolicyContinue, nil
+	case string(PodExitPolicyStop):
+		return PodExitPolicyStop, nil
+	default:
+		return PodExitPolicyUnsupported, fmt.Errorf("invalid pod exit policy: %q", policy)
+	}
+}

common/pkg/config/pod_exit_policy_test.go

@@ -0,0 +1,33 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParsePodExitPolicy(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected PodExitPolicy
+		mustFail bool
+	}{
+		{"", PodExitPolicyContinue, false},
+		{"continue", PodExitPolicyContinue, false},
+		{"stop", PodExitPolicyStop, false},
+		{"-", PodExitPolicyUnsupported, true},
+		{" stop", PodExitPolicyUnsupported, true},
+		{"continue ", PodExitPolicyUnsupported, true},
+		{"invalid", PodExitPolicyUnsupported, true},
+	}
+
+	for _, test := range tests {
+		parsed, err := ParsePodExitPolicy(test.input)
+		require.Equal(t, test.expected, parsed, "%v", test)
+		if test.mustFail {
+			require.Error(t, err, "%v", test)
+		} else {
+			require.NoError(t, err, "%v", test)
+		}
+	}
+}

common/pkg/config/testdata/containers_override.conf

@@ -11,6 +11,7 @@ image_default_format="v2s2"
 image_copy_tmp_dir="/tmp/foobar"
 events_logfile_path = "/tmp/events.log"
 events_logfile_max_size="500"
+pod_exit_policy="stop"
 
 [secrets]
 driver = "pass"