Add init containers to generate and play kube

Kubernetes has a concept of init containers that run and exit before
the regular containers in a pod are started. We added init containers
to podman pods as well. This patch adds support for generating init
containers in the kube yaml when a pod we are converting had init
containers. When playing a kube yaml, it detects an init container
and creates such a container in podman accordingly.
Note, only init containers created with the init type set to "always"
will be generated as the "once" option deletes the init container after
it has run and exited. Play kube will always creates init containers
with the "always" init container type.

Signed-off-by: Urvashi Mohnani <umohnani@redhat.com>

2 files changed, 33 insertions, 5 deletions

diff --git a/libpod/container.go b/libpod/container.go
index 0986a0d80..a4bbb5dd0 100644
--- a/libpod/container.go
+++ b/libpod/container.go
@@ -1062,6 +1062,11 @@ func (c *Container) IsInfra() bool {
 	return c.config.IsInfra
 }
 
+// IsInitCtr returns whether the container is an init container
+func (c *Container) IsInitCtr() bool {
+	return len(c.config.InitContainerType) > 0
+}
+
 // IsReadOnly returns whether the container is running in read only mode
 func (c *Container) IsReadOnly() bool {
 	return c.config.Spec.Root.Readonly
diff --git a/libpod/kube.go b/libpod/kube.go
index fff040adb..812bb101b 100644
--- a/libpod/kube.go
+++ b/libpod/kube.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -220,8 +221,14 @@ func (p *Pod) podWithContainers(containers []*Container, ports []v1.ContainerPor
 	deDupPodVolumes := make(map[string]*v1.Volume)
 	first := true
 	podContainers := make([]v1.Container, 0, len(containers))
+	podInitCtrs := []v1.Container{}
 	podAnnotations := make(map[string]string)
 	dnsInfo := v1.PodDNSConfig{}
+
+	// Let's sort the containers in order of created time
+	// This will ensure that the init containers are defined in the correct order in the kube yaml
+	sort.Slice(containers, func(i, j int) bool { return containers[i].CreatedTime().Before(containers[j].CreatedTime()) })
+
 	for _, ctr := range containers {
 		if !ctr.IsInfra() {
 			// Convert auto-update labels into kube annotations
@@ -229,6 +236,8 @@ func (p *Pod) podWithContainers(containers []*Container, ports []v1.ContainerPor
 				podAnnotations[k] = v
 			}
 
+			isInit := ctr.IsInitCtr()
+
 			ctr, volumes, _, err := containerToV1Container(ctr)
 			if err != nil {
 				return nil, err
@@ -245,6 +254,10 @@ func (p *Pod) podWithContainers(containers []*Container, ports []v1.ContainerPor
 				ctr.Ports = ports
 				first = false
 			}
+			if isInit {
+				podInitCtrs = append(podInitCtrs, ctr)
+				continue
+			}
 			podContainers = append(podContainers, ctr)
 			// Deduplicate volumes, so if containers in the pod share a volume, it's only
 			// listed in the volumes section once
@@ -278,13 +291,14 @@ func (p *Pod) podWithContainers(containers []*Container, ports []v1.ContainerPor
 	return newPodObject(
 		p.Name(),
 		podAnnotations,
+		podInitCtrs,
 		podContainers,
 		podVolumes,
 		&dnsInfo,
 		hostNetwork), nil
 }
 
-func newPodObject(podName string, annotations map[string]string, containers []v1.Container, volumes []v1.Volume, dnsOptions *v1.PodDNSConfig, hostNetwork bool) *v1.Pod {
+func newPodObject(podName string, annotations map[string]string, initCtrs, containers []v1.Container, volumes []v1.Volume, dnsOptions *v1.PodDNSConfig, hostNetwork bool) *v1.Pod {
 	tm := v12.TypeMeta{
 		Kind:       "Pod",
 		APIVersion: "v1",
@@ -304,9 +318,10 @@ func newPodObject(podName string, annotations map[string]string, containers []v1
 		Annotations:       annotations,
 	}
 	ps := v1.PodSpec{
-		Containers:  containers,
-		Volumes:     volumes,
-		HostNetwork: hostNetwork,
+		Containers:     containers,
+		HostNetwork:    hostNetwork,
+		InitContainers: initCtrs,
+		Volumes:        volumes,
 	}
 	if dnsOptions != nil {
 		ps.DNSConfig = dnsOptions
@@ -323,6 +338,7 @@ func newPodObject(podName string, annotations map[string]string, containers []v1
 // for a single container.  we "insert" that container description in a pod.
 func simplePodWithV1Containers(ctrs []*Container) (*v1.Pod, error) {
 	kubeCtrs := make([]v1.Container, 0, len(ctrs))
+	kubeInitCtrs := []v1.Container{}
 	kubeVolumes := make([]v1.Volume, 0)
 	hostNetwork := true
 	podDNS := v1.PodDNSConfig{}
@@ -333,6 +349,8 @@ func simplePodWithV1Containers(ctrs []*Container) (*v1.Pod, error) {
 			kubeAnnotations[k] = v
 		}
 
+		isInit := ctr.IsInitCtr()
+
 		if !ctr.HostNetwork() {
 			hostNetwork = false
 		}
@@ -340,7 +358,11 @@ func simplePodWithV1Containers(ctrs []*Container) (*v1.Pod, error) {
 		if err != nil {
 			return nil, err
 		}
-		kubeCtrs = append(kubeCtrs, kubeCtr)
+		if isInit {
+			kubeInitCtrs = append(kubeInitCtrs, kubeCtr)
+		} else {
+			kubeCtrs = append(kubeCtrs, kubeCtr)
+		}
 		kubeVolumes = append(kubeVolumes, kubeVols...)
 
 		// Combine DNS information in sum'd structure
@@ -379,6 +401,7 @@ func simplePodWithV1Containers(ctrs []*Container) (*v1.Pod, error) {
 	return newPodObject(
 		strings.ReplaceAll(ctrs[0].Name(), "_", ""),
 		kubeAnnotations,
+		kubeInitCtrs,
 		kubeCtrs,
 		kubeVolumes,
 		&podDNS,