Kubernetes cheatsheet#
Debugging using events#
Important
Always check the pods and deployment versions in the namespace to make sure you aren't debugging an issue in a version that's not the one you would expect
Events are a great way to understand what's going on under the hood in a Kubernetes cluster. By looking at them you can see if probes are failing, and other important signals from your cluster.
Get events for the whole namespace:
kubectl -n codacy get events --sort-by=.metadata.creationTimestamp
Get error events:
kubectl -n codacy get events --sort-by=.metadata.creationTimestamp --field-selector type=Error
Get warning events:
kubectl -n codacy get events --sort-by=.metadata.creationTimestamp --field-selector type=Warning
Get events from a specific pod:
kubectl -n codacy get events --sort-by=.metadata.creationTimestamp --field-selector involvedObject.name=<POD-NAME>
Helm#
Check all the previous releases in your namespace:
helm -n codacy history codacy
Rollback to a specific revision:
helm -n codacy rollback codacy <REVISION>
Edit configmap#
kubectl get configmaps
and
kubectl edit configmap <configmap-name>
Restart deployment of daemonset#
daemonsets#
kubectl get daemonsets
and
kubectl rollout restart daemonset/<daemonset-name>
deployment#
kubectl get deployment
and
kubectl rollout restart deployment/<deployment-name>
and
kubectl rollout status deployment/<deployment-name> -w
Read logs#
daemonset with multiple containers#
kubectl logs daemonset/<daemonset-name> <container-name> -f
service#
kubectl get svc
and
kubectl logs -l $(kubectl get svc/<service-name> -o=json | jq ".spec.selector" | jq -r 'to_entries|map("\(.key)=\(.value|tostring)")|.[]' | sed -e 'H;${x;s/\n/,/g;s/^,//;p;};d') -f
Open shell inside container#
kubectl exec -it daemonset/<daemonset-name> -c <container-name> sh
or
kubectl exec -it deployment/<deployment-name> sh
MicroK8s#
Session Manager SSH#
When using AWS Session Manager, to connect to the instance where you installed microk8s, since the CLI is very limited you will benefit from using these aliases:
alias kubectl='sudo microk8s.kubectl -n <namespace-name>'
alias helm='sudo helm'
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