The kubectl annotate command in Kubernetes is used to manage annotations associated with resources in the cluster. Annotations are key-value pairs that can provide additional metadata or configuration to Kubernetes objects without affecting their core functionality.
Annotating resources using kubectl annotate allows operators and developers to attach useful information to objects such as pods, services, or deployments. This metadata can be utilized by various tools and controllers within Kubernetes to make decisions or perform specific actions based on the annotations.
Here are several examples demonstrating how to use kubectl annotate effectively:
Example 1: Annotate a Pod
Annotate a specific pod named nginx with a version information:
kubectl annotate pod nginx version=v1.2.3
This command attaches the annotation version=v1.2.3 to the pod.
Verification: To verify if the annotation was applied, use:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: version=v1.2.3
Example 2: Annotate a Deployment
Add a descriptive annotation to a deployment named myapp:
kubectl annotate deployment myapp description="Production deployment"
This sets the annotation description="Production deployment" on the deployment object.
Verification: Check the deployment’s annotations:
kubectl describe deployment myapp | grep Annotations
Output example:
Annotations: description=Production deployment
Example 3: Annotate a Service
Attach a custom annotation to a service named backend:
kubectl annotate service backend app=finance
This adds the annotation app=finance to the service.
Verification: Verify the service’s annotations:
kubectl describe service backend | grep Annotations
Output example:
Annotations: app=finance
Example 4: Annotate with Labels
Use labels in annotations for more structured metadata:
kubectl annotate pod nginx labels='{ "env": "production", "tier": "frontend" }'
This command sets the labels as an annotation on the pod nginx.
Verification: View the pod’s annotations to confirm:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: labels={ "env": "production", "tier": "frontend" }
Example 5: Annotate with Timestamps
Utilize annotations for time-sensitive data:
kubectl annotate pod mypod timestamp=$(date +%s)
This sets the annotation timestamp with the current Unix timestamp on the pod.
Verification: Check the pod’s annotations:
kubectl describe pod mypod | grep Annotations
Output example:
Annotations: timestamp=1624682378
Example 6: Remove an Annotation
Remove a specific annotation from a pod:
kubectl annotate pod nginx version-
This removes the annotation version from the pod nginx.
Verification: Ensure the annotation is no longer present:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: <no annotations>
Example 7: Annotate Multiple Objects
Annotate multiple pods using a label selector:
kubectl annotate pods -l app=myapp env=dev
This adds the annotation env=dev to all pods labeled app=myapp.
Verification: List pods to confirm the annotations:
kubectl get pods -l app=myapp --show-labels
Output example:
NAME ... LABELS ... ANNOTATIONS
nginx ... app=myapp ... env=dev
Example 8: Annotate Using JSON Patch
Apply a JSON patch to add or update annotations:
kubectl annotate pod nginx --patch='{"metadata": {"annotations": {"newAnnotation": "value"}}}'
This method uses JSON patching to add or update the annotation newAnnotation on the pod nginx.
Verification: Describe the pod to see the updated annotations:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: newAnnotation=value
Example 9: Annotate with Custom Data
Attach custom data as an annotation:
kubectl annotate pod nginx custom-data='{"key": "value"}'
This sets the annotation custom-data='{"key": "value"}' on the pod nginx.
Verification: Describe the pod to check the custom annotation:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: custom-data={"key": "value"}
Example 10: Annotate with URLs
Store URLs or links as annotations:
kubectl annotate pod nginx url='https://example.com'
This annotates the pod nginx with a URL.
Verification: Verify the annotation on the pod:
kubectl describe pod nginx | grep Annotations
Output example:
Annotations: url=https://example.com
Also check similar articles.
Updating Kubernetes Labels with kubectl label
Building Kubernetes Customizations with kubectl kustomize
Waiting for Kubernetes Resources with kubectl wait
Replace Kubernetes Resources with kubectl replace
Patching Kubernetes Resources with kubectl patch
Discussion about this post