1. Defining and Querying Labels and Annotations
- Create three different Pods with the names
frontend
,backend
anddatabase
that use the imagenginx
. - Declare labels for those Pods as follows:
frontend: env=prod, team=shiny
backend: env=prod, team=legacy, app=v1.2.4
database: env=prod, team=storage
- Declare annotations for those Pods as follows:
frontend: contact=John Doe, commit=2d3mg3
backend: contact=Mary Harris
- Render the list of all Pods and their labels.
- Use label selectors on the command line to query for all production Pods that belong to the teams shiny and legacy.
- Remove the label env from the backend Pod and rerun the selection.
- Render the surrounding 3 lines of YAML of all Pods that have
annotations.
You can assign labels upon Pod creation with the --labels option.
$ kubectl run frontend --image=nginx --restart=Never --labels=env=prod,team=shiny
pod/frontend created
$ kubectl run backend --image=nginx --restart=Never --labels=env=prod,team=legacy,app=v1.2.4
pod/backend created
$ kubectl run database --image=nginx --restart=Never --labels=env=prod,team=storage
pod/database created
Edit the existing Pods with the edit command and add the annotations as follows:
apiVersion: v1
kind: Pod
metadata:
annotations:
commit: 2d3mg3
contact: John Doe
name: frontend
...
apiVersion: v1
kind: Pod
metadata:
annotations:
contact: 'Mary Harris'
name: backend
...
Render all Pods and their Pods including their assigned labels.
$ kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
backend 1/1 Running 0 41s app=v1.2.4,env=prod,team=legacy
database 1/1 Running 0 8s env=prod,team=storage
frontend 1/1 Running 0 1m env=prod,team=shiny
You can combine the selector rules into one expression.
$ kubectl get pods -l 'team in (shiny, legacy)',env=prod --show-labels
NAME READY STATUS RESTARTS AGE LABELS
backend 1/1 Running 0 19m app=v1.2.4,env=prod,team=legacy
frontend 1/1 Running 0 20m env=prod,team=shiny
You can add and remove labels with the label command. The selection now doesn’t match for the backend Pod anymore.
$ kubectl label pods backend env-
pod/backend labeled
$ kubectl get pods -l 'team in (shiny, legacy)',env==prod --show-labels
NAME READY STATUS RESTARTS AGE LABELS
frontend 1/1 Running 0 23m env=prod,team=shiny
The grep command can help with rendering any YAML code around the identified search term.
$ kubectl get pods -o yaml | grep -C 3 'annotations:'
apiVersion: v1
kind: Pod
metadata:
annotations:
/podIP: 192.168.60.163/32
contact: Mary Harris
creationTimestamp: 2019-05-10T17:57:38Z
--
--
apiVersion: v1
kind: Pod
metadata:
annotations:
/podIP: 192.168.60.147/32
creationTimestamp: 2019-05-10T17:58:11Z
labels:
--
--
apiVersion: v1
kind: Pod
metadata:
annotations:
/podIP: 192.168.60.159/32
commit: 2d3mg3
contact: John Doe
2. Performing Rolling Updates for a Deployment
- Create a Deployment named
deploy
with3 replicas.
The Pods should use thenginx
image and the namenginx
. The Deployment uses the labeltier=backend
. The Pods should use the labelapp=v1
. - List the Deployment and ensure that the correct number of replicas
is running. - Update the image to nginx:latest.
- Verify that the change has been rolled out to all replicas.
- Scale the Deployment to 5 replicas.
- Have a look at the Deployment rollout history.
- Revert the Deployment to revision 1.
- Ensure that the Pods use the image nginx.
Generate the YAML for a Deployment plus Pod for further editing.
$ kubectl create deployment deploy --image=nginx --dry-run -o yaml > deploy.yaml
Edit the labels. The selector should match the labels of the Pods
. Change the replicas from 1 to 3
.
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
labels:
tier: backend
name: deploy
spec:
replicas: 1
selector:
matchLabels:
app: v1
strategy: {}
template:
metadata:
creationTimestamp: null
labels:
app: v1
spec:
containers:
- image: nginx
name: nginx
resources: {}
status: {}
Create the deployment by pointing it to the YAML file.
$ kubectl create -f deploy.yaml
deployment.apps/deploy created
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
deploy 3 3 3 1 4s
Set the new image and check the revision history.
$ kubectl set image deployment/deploy nginx=nginx:latest
deployment.extensions/deploy image updated
$ kubectl rollout history deploy
deployment.extensions/deploy
REVISION CHANGE-CAUSE
1 <none>
2 <none>
$ kubectl rollout history deploy --revision=2
deployment.extensions/deploy with revision #2
Pod Template:
Labels: app=v1
pod-template-hash=1370799740
Containers:
nginx:
Image: nginx:latest
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
Now scale the Deployment to 5 replicas
.
$ kubectl scale deployments deploy --replicas=5
deployment.extensions/deploy scaled
Roll back to revision 1
. You will see the new revision. Inspecting the revision should show the image nginx.
$ kubectl rollout undo deployment/deploy --to-revision=1
deployment.extensions/deploy
$ kubectl rollout history deploy
deployment.extensions/deploy
REVISION CHANGE-CAUSE
2 <none>
3 <none>
$ kubectl rollout history deploy --revision=3
deployment.extensions/deploy with revision #3
Pod Template:
Labels: app=v1
pod-template-hash=454670702
Containers:
nginx:
Image: nginx
Port: <none>
Host Port: <none>
Environment: <none>
Mounts: <none>
Volumes: <none>
3. Creating a Scheduled Container Operation
- Create a
CronJob
namedcurrent-date
that runsevery minute
and executes the shell commandecho "Current date: $(date)"
. - Watch the jobs as they are being scheduled.
- Identify one of the Pods that ran the CronJob and render the logs.
- Determine the number of successful executions the CronJob will keep
in its history. Delete the Job.
答案:
The run command is deprecated but it provides a good shortcut for creating a CronJob with a single command.
注意:此命令kubectl v1.8并不会显示创建cronjob成功,仅是pod
$ kubectl run current-date --schedule="* * * * *" --restart=OnFailure --image=nginx -- /bin/sh -c 'echo "Current date: $(date)"'
kubectl run --generator=cronjob/v1beta1 is DEPRECATED and will be removed in a future version. Use kubectl create instead.
cronjob.batch/hello created
正确命令:
kubectl create cronjob current-update --image=nginx --schedule="* * * * *" --restart=OnFailure -- /bin/sh -c 'echo "Current date: $(date)"'
Watch the Jobs as they are executed.
$ kubectl get cronjobs --watch
NAME COMPLETIONS DURATION AGE
current-date-1557522540 1/1 3s 103s
current-date-1557522600 1/1 4s 43s
Identify one of the Pods (the label indicates the Job name) and render its logs.
$ kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
current-date-1557522540-dp8l9 0/1 Completed 0 1m controller-uid=3aaabf96-7369-11e9-96c6-025000000001,job-name=current-date-1557523140,run=current-date
$ kubectl logs current-date-1557522540-dp8l9
Current date: Fri May 10 21:09:12 UTC 2019
The value of the attribute successfulJobsHistoryLimit defines how many executions are kept in the history.
$ kubectl get cronjobs current-date -o yaml | grep successfulJobsHistoryLimit:
successfulJobsHistoryLimit: 3
Finally, delete the CronJob.
$ kubectl delete cronjob current-date