Kubectl Explain#
As great as the kubernetes documentation site is. It is nice to able to query info while you are locked inside a terminal. I’ve always been making use of “kubectl describe” but haven’t started really using “kubectl explain” until now.
It makes querying acceptable fields for a resource very easy (kubectl explain deployment.spec), but the really shines when you pipe it’s outputs into CLI tools. Take yq for example, a non standard Linux tool used to process YAML content in the command line or bash script.
Instead of manually opening or using kubectl describe to view a resources specific values, you can use yq to only output the content you need i.e “spec.strategy”. kubectl explain also works with custom resource definitions!
Output of kubectl -n karakeep get deployments.apps web -o yaml | yq .spec.strategy
{
"rollingUpdate": {
"maxSurge": "25%",
"maxUnavailable": "25%"
},
"type": "RollingUpdate"
}Output of kubectl explain deployment.spec.strategy
GROUP: apps
KIND: Deployment
VERSION: v1
FIELD: strategy <DeploymentStrategy>
DESCRIPTION:
The deployment strategy to use to replace existing pods with new ones.
DeploymentStrategy describes how to replace existing pods with new ones.
FIELDS:
rollingUpdate <RollingUpdateDeployment>
Rolling update config params. Present only if DeploymentStrategyType =
RollingUpdate.
type <string>
enum: Recreate, RollingUpdate
Type of deployment. Can be "Recreate" or "RollingUpdate". Default is
RollingUpdate.
Possible enum values:
- `"Recreate"` Kill all existing pods before creating new ones.
- `"RollingUpdate"` Replace the old ReplicaSets by new one using rolling
update i.e gradually scale down the old ReplicaSets and scale up the new
one.Sources#
https://www.baeldung.com/linux/yq-utility-processing-yaml
https://kubernetes.io/docs/reference/kubectl/generated/kubectl_explain/
