Active-standby pods in a container orchestration environment
Container orchestration platforms, such as Kubernetes, automatically manage the execution of applications in containers on host computing systems. An application may include component applications that execute in different containers and a container orchestration platform may organize the containers for those component applications into a pod for the application. To spread the load for the application, the container orchestration platform may enable creation of more than one pod for a single application. Once created, any of the multiple pods may be selected to handle a request to the application. As such, all of the pods are considered active by the container orchestration platform.
1. A method comprising:
in an active-standby controller:
identifying creation of pods for executing an application in a computing cluster, wherein a control plane creates the pods;
providing an active-pod label to the control plane, wherein the control plane updates pod-selection criteria with the active-pod label, wherein the pod-selection criteria is used by a service executing in the computing cluster to select one or more of the pods to receive requests for the application; and
instructing the control plane to add the active-pod label to a first pod of the pods, wherein the service selects the first pod to handle a request for the application based on the pod-selection criteria after the active-pod label is added to the first pod.
2. The method of claim 1 , comprising:
identifying a failure of the first pod;
in response to the failure, instructing the control plane to add the active-pod label to a second pod of the pods, wherein the service selects the second pod to handle a second request for the application based on the pod-selection criteria after the active-pod label is added to the second pod.
3. The method of claim 2 , comprising:
in response to the failure, instructing the control plane to remove the active-pod label from the first pod.
4. The method of claim 3 , wherein the second pod is selected from a queue of the pods that are not active, and the method comprising:
after instructing the control plane to remove the active-pod label, determining that the first pod is ready; and
in response to determining that the first pod is ready, adding the first pod to the queue.
5. The method of claim 1 , wherein identifying the creation of the pods comprises:
identifying the pods as having an active-standby label, wherein the active-standby label is a label included in the pods by the control plane.
6. The method of claim 5 , comprising:
registering the pods in response to identifying the pods as having the active-standby label.
7. The method of claim 6 , comprising:
adding the pods to a queue of the pods that are not active; and
selecting the first pod from the queue.
8. The method of claim 5 , wherein the active-standby label is included in service parameters for the application received by the control plane from a user.
9. The method of claim 8 , wherein the service parameters further include a strategy label defining a number of active pods and a number of standby pods for the application, and the method comprising:
recognizing the service includes the strategy label; and
implementing the number of active pods and the number of standby pods, wherein the first pod is one pod of the number of active pods.
10. The method of claim 1 , comprising:
generating random data to use as the active-pod label.
11. An apparatus comprising:
one or more computer readable storage media;
a processing system operatively coupled with the one or more computer readable storage media; and
program instructions stored on the one or more computer readable storage media that, when read and executed by the processing system, direct the processing system to:
in an active-standby controller:
identify creation of pods for executing an application in a computing cluster, wherein a control plane creates the pods;
provide an active-pod label to the control plane, wherein the control plane updates pod-selection criteria with the active-pod label, wherein the pod-selection criteria is used by a service executing in the computing cluster to select one or more of the pods to receive requests for the application; and
instruct the control plane to add the active-pod label to a first pod of the pods, wherein the service selects the first pod to handle a request for the application based on the pod-selection criteria after the active-pod label is added to the first pod.
12. The apparatus of claim 11 , wherein the program instructions direct the processing system to:
identify a failure of the first pod;
in response to the failure, instruct the control plane to add the active-pod label to a second pod of the pods, wherein the service selects the second pod to handle a second request for the application based on the pod-selection criteria after the active-pod label is added to the second pod.
13. The apparatus of claim 12 , wherein the program instructions direct the processing system to:
in response to the failure, instruct the control plane to remove the active-pod label from the first pod.
14. The apparatus of claim 13 , wherein the second pod is selected from a queue of the pods that are not active, and wherein the program instructions direct the processing system to:
after instructing the control plane to remove the active-pod label, determine that the first pod is ready; and
in response to determining that the first pod is ready, add the first pod to the queue.
15. The apparatus of claim 11 , wherein to identify the creation of the pods, the program instructions direct the processing system to:
identify the pods as having an active-standby label, wherein the active-standby label is a label included in the pods by the control plane.
16. The apparatus of claim 15 , wherein the program instructions direct the processing system to:
register the pods in response to identifying the pods as having the active-standby label.
17. The apparatus of claim 16 , wherein the program instructions direct the processing system to:
add the pods to a queue of the pods that are not active; and
select the first pod from the queue.
18. The apparatus of claim 15 , wherein the active-standby label is included in service parameters for the application received by the control plane from a user.
19. The apparatus of claim 18 , wherein the service parameters further include a strategy label defining a number of active pods and a number of standby pods for the application.
20. One or more non-transitory computer readable storage media having program instructions stored thereon that, when read and executed by a processing system, direct the processing system to: in an active-standby controller: identify creation of pods for executing an application in a computing cluster, wherein a control plane creates the pods; provide an active-pod label to the control plane, wherein the control plane updates pod-selection criteria with the active-pod label, wherein the pod-selection criteria is used by a service executing in the computing cluster to select one or more of the pods to receive requests for the application; and instruct the control plane to add the active-pod label to a first pod of the pods, wherein the service selects the first pod to handle a request for the application based on the pod-selection criteria after the active-pod label is added to the first pod.