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:
cni.projectcalico.org/podIP: 192.168.60.163/32
contact: Mary Harris
creationTimestamp: 2019-05-10T17:57:38Z
--
--
apiVersion: v1
kind: Pod
metadata:
annotations:
cni.projectcalico.org/podIP: 192.168.60.147/32
creationTimestamp: 2019-05-10T17:58:11Z
labels:
--
--
apiVersion: v1
kind: Pod
metadata:
annotations:
cni.projectcalico.org/podIP: 192.168.60.159/32
commit: 2d3mg3
contact: John Doe
2. Performing Rolling Updates for a Deployment
Create a Deployment named deploy with 3 replicas. The Pods should use the nginx image and the name nginx. The Deployment uses the label tier=backend. The Pods should use the label app=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.
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
Create a CronJob named current-date that runs every minute and executes the shell command echo "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
$ 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.