3 min read | by Jordi Prats
If we take a look all the possible properties for a Pod definition we might notice that there's one to limit the time a Pod can be running:
apiVersion: v1 kind: Pod metadata: name: test spec: activeDeadlineSeconds: 10 containers: - args: - sleep - 24h image: alpine name: test If we give it a try it will work as expected for a single Pod:
$ kubectl get pods --watch NAME READY STATUS RESTARTS AGE test 0/1 DeadlineExceeded 0 39s For objects such a Job (or a CronJob) that we might want to be able to cancel if a Pod runs for too long it makes perfect sense:
apiVersion: batch/v1 kind: CronJob metadata: name: democron-sitemapgen spec: schedule: '* * * * *' successfulJobsHistoryLimit: 1 failedJobsHistoryLimit: 1 jobTemplate: metadata: name: democron-sitemapgen spec: template: spec: restartPolicy: OnFailure activeDeadlineSeconds: 40 containers: - name: democron-sitemapgen image: alpine:latest command: - sleep - 24h Trying this out we will be able to see how it kills the Pod once the activeDeadlineSeconds is reached:
$ kubectl get pods --watch NAME READY STATUS RESTARTS AGE democron-sitemapgen-27440182--1-mcldv 0/1 Pending 0 0s democron-sitemapgen-27440182--1-mcldv 0/1 Pending 0 0s democron-sitemapgen-27440182--1-mcldv 0/1 ContainerCreating 0 1s democron-sitemapgen-27440182--1-mcldv 1/1 Running 0 12s democron-sitemapgen-27440182--1-mcldv 1/1 DeadlineExceeded 0 40s democron-sitemapgen-27440182--1-t874q 0/1 Pending 0 0s democron-sitemapgen-27440182--1-t874q 0/1 Pending 0 0s democron-sitemapgen-27440182--1-t874q 0/1 ContainerCreating 0 1s democron-sitemapgen-27440182--1-t874q 1/1 Running 0 12s democron-sitemapgen-27440182--1-mcldv 0/1 Error 0 77s democron-sitemapgen-27440182--1-t874q 1/1 DeadlineExceeded 0 40s democron-sitemapgen-27440182--1-cjbzw 0/1 Pending 0 0s democron-sitemapgen-27440182--1-cjbzw 0/1 Pending 0 0s democron-sitemapgen-27440182--1-cjbzw 0/1 ContainerCreating 0 0s democron-sitemapgen-27440182--1-cjbzw 1/1 Running 0 12s (...) But if we try to the same on a Deployment like this:
apiVersion: apps/v1 kind: Deployment metadata: name: test-deploy labels: demo: test spec: replicas: 1 selector: matchLabels: demo: test template: metadata: labels: demo: test spec: activeDeadlineSeconds: 10 containers: - args: - sleep - 24h image: alpine name: test It won't allow us to have it on the Pod template:
$ kubectl apply -f test.yaml The Deployment "test-deploy" is invalid: spec.template.spec.activeDeadlineSeconds: Forbidden: activeDeadlineSeconds in ReplicaSet is not Supported A deployment is intended for workloads that are supposed to be running perpetually, so the activeDeadlineSeconds doesn't make sense for that use case. If we want to be able to refresh the Pods on a Deployment (or a StatefulSet) we can use the bestby controller. With it we can use a label to defined how often Pods need to be refreshed
Posted on 07/03/2022