forked from zalando/postgres-operator
/
pod.go
358 lines (291 loc) · 10.9 KB
/
pod.go
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package cluster
import (
"fmt"
"math/rand"
v1 "k8s.io/api/core/v1"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"github.com/zalando-incubator/postgres-operator/pkg/spec"
"github.com/zalando-incubator/postgres-operator/pkg/util"
"k8s.io/api/apps/v1beta1"
)
func (c *Cluster) listPods() ([]v1.Pod, error) {
listOptions := metav1.ListOptions{
LabelSelector: c.labelsSet(false).String(),
}
pods, err := c.KubeClient.Pods(c.Namespace).List(listOptions)
if err != nil {
return nil, fmt.Errorf("could not get list of pods: %v", err)
}
return pods.Items, nil
}
func (c *Cluster) getRolePods(role PostgresRole) ([]v1.Pod, error) {
listOptions := metav1.ListOptions{
LabelSelector: c.roleLabelsSet(false, role).String(),
}
pods, err := c.KubeClient.Pods(c.Namespace).List(listOptions)
if err != nil {
return nil, fmt.Errorf("could not get list of pods: %v", err)
}
if role == Master && len(pods.Items) > 1 {
return nil, fmt.Errorf("too many masters")
}
return pods.Items, nil
}
func (c *Cluster) deletePods() error {
c.logger.Debugln("deleting pods")
pods, err := c.listPods()
if err != nil {
return err
}
for _, obj := range pods {
podName := util.NameFromMeta(obj.ObjectMeta)
c.logger.Debugf("deleting pod %q", podName)
if err := c.deletePod(podName); err != nil {
c.logger.Errorf("could not delete pod %q: %v", podName, err)
} else {
c.logger.Infof("pod %q has been deleted", podName)
}
}
if len(pods) > 0 {
c.logger.Debugln("pods have been deleted")
} else {
c.logger.Debugln("no pods to delete")
}
return nil
}
func (c *Cluster) deletePod(podName spec.NamespacedName) error {
c.setProcessName("deleting pod %q", podName)
ch := c.registerPodSubscriber(podName)
defer c.unregisterPodSubscriber(podName)
if err := c.KubeClient.Pods(podName.Namespace).Delete(podName.Name, c.deleteOptions); err != nil {
return err
}
return c.waitForPodDeletion(ch)
}
func (c *Cluster) unregisterPodSubscriber(podName spec.NamespacedName) {
c.logger.Debugf("unsubscribing from pod %q events", podName)
c.podSubscribersMu.Lock()
defer c.podSubscribersMu.Unlock()
if _, ok := c.podSubscribers[podName]; !ok {
panic("subscriber for pod '" + podName.String() + "' is not found")
}
close(c.podSubscribers[podName])
delete(c.podSubscribers, podName)
}
func (c *Cluster) registerPodSubscriber(podName spec.NamespacedName) chan PodEvent {
c.logger.Debugf("subscribing to pod %q", podName)
c.podSubscribersMu.Lock()
defer c.podSubscribersMu.Unlock()
ch := make(chan PodEvent)
if _, ok := c.podSubscribers[podName]; ok {
panic("pod '" + podName.String() + "' is already subscribed")
}
c.podSubscribers[podName] = ch
return ch
}
func (c *Cluster) movePodFromEndOfLifeNode(pod *v1.Pod) (*v1.Pod, error) {
var (
eol bool
err error
newPod *v1.Pod
)
podName := util.NameFromMeta(pod.ObjectMeta)
if eol, err = c.podIsEndOfLife(pod); err != nil {
return nil, fmt.Errorf("could not get node %q: %v", pod.Spec.NodeName, err)
} else if !eol {
c.logger.Infof("check failed: pod %q is already on a live node", podName)
return pod, nil
}
c.setProcessName("moving pod %q out of end-of-life node %q", podName, pod.Spec.NodeName)
c.logger.Infof("moving pod %q out of the end-of-life node %q", podName, pod.Spec.NodeName)
if newPod, err = c.recreatePod(podName); err != nil {
return nil, fmt.Errorf("could not move pod: %v", err)
}
if newPod.Spec.NodeName == pod.Spec.NodeName {
return nil, fmt.Errorf("pod %q remained on the same node", podName)
}
if eol, err = c.podIsEndOfLife(newPod); err != nil {
return nil, fmt.Errorf("could not get node %q: %v", pod.Spec.NodeName, err)
} else if eol {
c.logger.Warningf("pod %q moved to end-of-life node %q", podName, newPod.Spec.NodeName)
return newPod, nil
}
c.logger.Infof("pod %q moved from node %q to node %q", podName, pod.Spec.NodeName, newPod.Spec.NodeName)
return newPod, nil
}
func (c *Cluster) masterCandidate(oldNodeName string) (*v1.Pod, error) {
// Wait until at least one replica pod will come up
if err := c.waitForAnyReplicaLabelReady(); err != nil {
c.logger.Warningf("could not find at least one ready replica: %v", err)
}
replicas, err := c.getRolePods(Replica)
if err != nil {
return nil, fmt.Errorf("could not get replica pods: %v", err)
}
if len(replicas) == 0 {
c.logger.Warningf("no available master candidates, migration will cause longer downtime of Postgres cluster")
return nil, nil
}
for i, pod := range replicas {
// look for replicas running on live nodes. Ignore errors when querying the nodes.
if pod.Spec.NodeName != oldNodeName {
eol, err := c.podIsEndOfLife(&pod)
if err == nil && !eol {
return &replicas[i], nil
}
}
}
c.logger.Warningf("no available master candidates on live nodes")
return &replicas[rand.Intn(len(replicas))], nil
}
// MigrateMasterPod migrates master pod via failover to a replica
func (c *Cluster) MigrateMasterPod(podName spec.NamespacedName) error {
var (
masterCandidatePod *v1.Pod
err error
eol bool
)
oldMaster, err := c.KubeClient.Pods(podName.Namespace).Get(podName.Name, metav1.GetOptions{})
if err != nil {
return fmt.Errorf("could not get pod: %v", err)
}
c.logger.Infof("starting process to migrate master pod %q", podName)
if eol, err = c.podIsEndOfLife(oldMaster); err != nil {
return fmt.Errorf("could not get node %q: %v", oldMaster.Spec.NodeName, err)
}
if !eol {
c.logger.Debugf("no action needed: master pod is already on a live node")
return nil
}
if role := PostgresRole(oldMaster.Labels[c.OpConfig.PodRoleLabel]); role != Master {
c.logger.Warningf("no action needed: pod %q is not the master (anymore)", podName)
return nil
}
// we must have a statefulset in the cluster for the migration to work
if c.Statefulset == nil {
var sset *v1beta1.StatefulSet
if sset, err = c.KubeClient.StatefulSets(c.Namespace).Get(c.statefulSetName(),
metav1.GetOptions{}); err != nil {
return fmt.Errorf("could not retrieve cluster statefulset: %v", err)
}
c.Statefulset = sset
}
// We may not have a cached statefulset if the initial cluster sync has aborted, revert to the spec in that case.
if *c.Statefulset.Spec.Replicas > 1 {
if masterCandidatePod, err = c.masterCandidate(oldMaster.Spec.NodeName); err != nil {
return fmt.Errorf("could not find suitable replica pod as candidate for failover: %v", err)
}
} else {
c.logger.Warningf("migrating single pod cluster %q, this will cause downtime of the Postgres cluster until pod is back", c.clusterName())
}
// there are two cases for each postgres cluster that has its master pod on the node to migrate from:
// - the cluster has some replicas - migrate one of those if necessary and failover to it
// - there are no replicas - just terminate the master and wait until it respawns
// in both cases the result is the new master up and running on a new node.
if masterCandidatePod == nil {
if _, err = c.movePodFromEndOfLifeNode(oldMaster); err != nil {
return fmt.Errorf("could not move pod: %v", err)
}
return nil
}
if masterCandidatePod, err = c.movePodFromEndOfLifeNode(masterCandidatePod); err != nil {
return fmt.Errorf("could not move pod: %v", err)
}
masterCandidateName := util.NameFromMeta(masterCandidatePod.ObjectMeta)
if err := c.Switchover(oldMaster, masterCandidateName); err != nil {
return fmt.Errorf("could not failover to pod %q: %v", masterCandidateName, err)
}
return nil
}
// MigrateReplicaPod recreates pod on a new node
func (c *Cluster) MigrateReplicaPod(podName spec.NamespacedName, fromNodeName string) error {
replicaPod, err := c.KubeClient.Pods(podName.Namespace).Get(podName.Name, metav1.GetOptions{})
if err != nil {
return fmt.Errorf("could not get pod: %v", err)
}
c.logger.Infof("migrating replica pod %q to live node", podName)
if replicaPod.Spec.NodeName != fromNodeName {
c.logger.Infof("check failed: pod %q has already migrated to node %q", podName, replicaPod.Spec.NodeName)
return nil
}
if role := PostgresRole(replicaPod.Labels[c.OpConfig.PodRoleLabel]); role != Replica {
return fmt.Errorf("check failed: pod %q is not a replica", podName)
}
_, err = c.movePodFromEndOfLifeNode(replicaPod)
if err != nil {
return fmt.Errorf("could not move pod: %v", err)
}
return nil
}
func (c *Cluster) recreatePod(podName spec.NamespacedName) (*v1.Pod, error) {
ch := c.registerPodSubscriber(podName)
defer c.unregisterPodSubscriber(podName)
stopChan := make(chan struct{})
if err := c.KubeClient.Pods(podName.Namespace).Delete(podName.Name, c.deleteOptions); err != nil {
return nil, fmt.Errorf("could not delete pod: %v", err)
}
if err := c.waitForPodDeletion(ch); err != nil {
return nil, err
}
pod, err := c.waitForPodLabel(ch, stopChan, nil)
if err != nil {
return nil, err
}
c.logger.Infof("pod %q has been recreated", podName)
return pod, nil
}
func (c *Cluster) recreatePods() error {
c.setProcessName("starting to recreate pods")
ls := c.labelsSet(false)
namespace := c.Namespace
listOptions := metav1.ListOptions{
LabelSelector: ls.String(),
}
pods, err := c.KubeClient.Pods(namespace).List(listOptions)
if err != nil {
return fmt.Errorf("could not get the list of pods: %v", err)
}
c.logger.Infof("there are %d pods in the cluster to recreate", len(pods.Items))
var (
masterPod, newMasterPod, newPod *v1.Pod
)
replicas := make([]spec.NamespacedName, 0)
for i, pod := range pods.Items {
role := PostgresRole(pod.Labels[c.OpConfig.PodRoleLabel])
if role == Master {
masterPod = &pods.Items[i]
continue
}
podName := util.NameFromMeta(pods.Items[i].ObjectMeta)
if newPod, err = c.recreatePod(podName); err != nil {
return fmt.Errorf("could not recreate replica pod %q: %v", util.NameFromMeta(pod.ObjectMeta), err)
}
if newRole := PostgresRole(newPod.Labels[c.OpConfig.PodRoleLabel]); newRole == Replica {
replicas = append(replicas, util.NameFromMeta(pod.ObjectMeta))
} else if newRole == Master {
newMasterPod = newPod
}
}
if masterPod != nil {
// failover if we have not observed a master pod when re-creating former replicas.
if newMasterPod == nil && len(replicas) > 0 {
if err := c.Switchover(masterPod, masterCandidate(replicas)); err != nil {
c.logger.Warningf("could not perform switch over: %v", err)
}
} else if newMasterPod == nil && len(replicas) == 0 {
c.logger.Warningf("cannot perform switch over before re-creating the pod: no replicas")
}
c.logger.Infof("recreating old master pod %q", util.NameFromMeta(masterPod.ObjectMeta))
if _, err := c.recreatePod(util.NameFromMeta(masterPod.ObjectMeta)); err != nil {
return fmt.Errorf("could not recreate old master pod %q: %v", util.NameFromMeta(masterPod.ObjectMeta), err)
}
}
return nil
}
func (c *Cluster) podIsEndOfLife(pod *v1.Pod) (bool, error) {
node, err := c.KubeClient.Nodes().Get(pod.Spec.NodeName, metav1.GetOptions{})
if err != nil {
return false, err
}
return node.Spec.Unschedulable || !util.MapContains(node.Labels, c.OpConfig.NodeReadinessLabel), nil
}