Change an Existing Configuration #
Create Example Deployment #
# Create a manifest for the deployment
vi nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: nginx
name: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx
name: nginx
resources: {}
status: {}
# Create the deployment
kubectl apply -f nginx-deployment.yaml
Adopt the Deployment Configuration: Non-Disruptive #
Kubectl Apply #
Change the deployment configuration and add for example a port:
# Adopt the manifest
vi nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: nginx
name: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx
name: nginx
ports: # Add a port
- containerPort: 80
protocol: TCP
resources: {}
status: {}
# Update the existing resource from the adopted configuration
kubectl apply -f nginx-deployment.yaml
# Verify the port:
kubectl describe deployment nginx | grep Port
# Shell output:
Port: 80/TCP
Host Port: 0/TC
Note: kubectl apply instead of kubectl create is generally recommended when managing resources declaratively in Kubernetes. kubectl apply automatically adds the kubectl.kubernetes.io/last-applied-configuration annotation to the resource, which stores the last applied configuration, to track changes.
Kubectl Edit #
This opens the current resource configuration in a text editor, allowing you to make changes directly.
Change the deployment configuration and add for example a port:
# Open the deployment configuration
kubectl edit deployment nginx
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: "1"
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"creationTimestamp":null,"labels":{"app":"nginx"},"name":"nginx","namespace":"default"},"spec":{"replicas":1,"selector":{"matchLabels":{"app":"nginx"}},"strategy":{},"template":{"metadata":{"creationTimestamp":null,"labels":{"app":"nginx"}},"spec":{"containers":[{"image":"nginx","name":"nginx","resources":{}}]}}},"status":{}}
creationTimestamp: "2024-11-04T18:24:08Z"
generation: 1
labels:
app: nginx
name: nginx
namespace: default
resourceVersion: "12855"
uid: a14736df-9f28-4ffa-ab4b-b75268e28e77
spec:
progressDeadlineSeconds: 600
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
app: nginx
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx
imagePullPolicy: Always
name: nginx
ports: # Add a port
- containerPort: 80
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
status:
status:
availableReplicas: 1
conditions:
- lastTransitionTime: "2024-11-04T18:24:10Z"
lastUpdateTime: "2024-11-04T18:24:10Z"
message: Deployment has minimum availability.
reason: MinimumReplicasAvailable
status: "True"
type: Available
- lastTransitionTime: "2024-11-04T18:24:08Z"
lastUpdateTime: "2024-11-04T18:24:10Z"
message: ReplicaSet "nginx-7854ff8877" has successfully progressed.
reason: NewReplicaSetAvailable
status: "True"
type: Progressing
observedGeneration: 1
readyReplicas: 1
replicas: 1
updatedReplicas: 1
- Save the configuration
# Shell output:
deployment.apps/nginx edited
# Verify the port:
kubectl describe deployment nginx | grep Port
# Shell output:
Port: 80/TCP
Host Port: 0/TC
Kubectl Patch #
Useful for partial configuration updates.
Change the deployment configuration and add for example a port:
# Example: JSON Patch
kubectl patch deployment nginx --type='json' -p='[{"op": "add", "path": "/spec/template/spec/containers/0/ports", "value": [{"containerPort": 80, "protocol": "TCP"}]}]'
# Example: YAML Merge Patch
kubectl patch deployment nginx --type='merge' -p='{"spec": {"template": {"spec": {"containers": [{"name": "nginx", "image": "nginx", "ports": [{"containerPort": 80, "protocol": "TCP"}]}]}}}}'
# Verify the port:
kubectl describe deployment nginx | grep Port
# Shell output:
Port: 80/TCP
Host Port: 0/TC
Adopt the Deployment Configuration: Disruptive #
Kubectl Replace #
Change the deployment configuration and add for example a port:
# Adopt the manifest
vi nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
app: nginx
name: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: nginx
spec:
containers:
- image: nginx
name: nginx
ports: # Add a port
- containerPort: 80
protocol: TCP
resources: {}
status: {}
# List pods
kubectl get pods
# Shell output:
NAME READY STATUS RESTARTS AGE
nginx-8678697d5c-tcs77 1/1 Running 0 86s
# Terminate and recreate the resources
kubectl replace -f nginx-deployment.yaml
# Shell output:
deployment.apps/nginx replaced
# List pods
kubectl get pods
# Shell output:
NAME READY STATUS RESTARTS AGE
nginx-797d4647d-4jg4c 1/1 Running 0 1s
nginx-8678697d5c-tcs77 1/1 Terminating 0 97s
# Shell output:
NAME READY STATUS RESTARTS AGE
nginx-797d4647d-4jg4c 1/1 Running 0 8s
Delete the Deployment #
# Delete the deployment
kubectl delete deployment nginx
Kubernetes Update Rollouts and Rollbacks with Set Image Command #
Create Example Deployment #
# Create a deployment with Nginx container
kubectl create deployment example-deployment --image=nginx:1.26.2
# Verify the pod
kubectl get pod
# Shell output:
NAME READY STATUS RESTARTS AGE
example-deployment-bb86db598-r52hg 1/1 Running 0 33s
Update Rollout #
# Update the deployment to a new image version
kubectl set image deployment example-deployment nginx=nginx:1.27.2
# Shell output:
deployment.apps/example-deployment image updated
# Annotate the deployment with the change cause
kubectl annotate deployment example-deployment kubernetes.io/change-cause="Updated image to nginx:1.27.2"
# Shell output:
deployment.apps/example-deployment annotated
Verify Deployment Image #
# Verify the pod
kubectl get pods
# Shell output:
NAME READY STATUS RESTARTS AGE
example-deployment-7bfd79855f-txcqw 1/1 Running 0 3m9s
# List deployment details
kubectl describe deployment example-deployment
# Shell output:
...
Pod Template:
Labels: app=example-deployment
Containers:
nginx:
Image: nginx:1.27.2
...
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ScalingReplicaSet 2m58s deployment-controller Scaled up replica set example-deployment-bb86db598 to 1
Normal ScalingReplicaSet 116s deployment-controller Scaled up replica set example-deployment-7bfd79855f to 1
Normal ScalingReplicaSet 115s deployment-controller Scaled down replica set example-deployment-bb86db598 to 0 from 1
Rollback: Most Recent Previous Version #
# Roll back to the most recent previous version
kubectl rollout undo deployments example-deployment
# Shell output:
deployment.apps/example-deployment rolled back
# Annotate the deployment with the change cause
kubectl annotate deployment example-deployment kubernetes.io/change-cause="Rollback to image nginx:1.26.2"
# Shell output:
deployment.apps/example-deployment annotated
View Rollout History #
# List rollout history
kubectl rollout history deployment example-deployment
# Shell output:
REVISION CHANGE-CAUSE
2 Updated image to nginx:1.27.2
3 Rollback to image nginx:1.26.2
Rollback to a Specific Revision #
# Rollback to a Specific Revision: Revision 2
kubectl rollout undo deployment example-deployment --to-revision=2
# Shell output:
deployment.apps/example-deployment rolled back
# Annotate the deployment with the change cause
kubectl annotate deployment example-deployment kubernetes.io/change-cause="Rollback to image nginx:1.27.2"
# Shell output:
deployment.apps/example-deployment annotated
View Rollout History:
# List rollout history
kubectl rollout history deployment example-deployment
# Shell output:
REVISION CHANGE-CAUSE
3 Rollback to image nginx:1.26.2
4 Rollback to image nginx:1.27.2