I would like to run a shell script inside the Kubernetes using CronJob, here is my CronJon.yaml file :
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
imagePullPolicy: IfNotPresent
command:
- /bin/sh
- -c
- /home/admin_/test.sh
restartPolicy: OnFailure
CronJob has been created ( kubectl apply -f CronJob.yaml )
when I get the list of cronjob I can see the cron job ( kubectl get cj ) and when I run "kubectl get pods" I can see the pod is being created, but pod crashes.
Can anyone help me to learn how I can create a CronJob inside the Kubernetes please ?
As correctly pointed out in the comments, you need to provide the script file in order to execute it via your CronJob. You can do that by mounting the file within a volume. For example, your CronJob could look like this:
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: hello
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: hello
image: busybox
imagePullPolicy: IfNotPresent
command:
- /bin/sh
- -c
- /myscript/test.sh
volumeMounts:
- name: script-dir
mountPath: /myscript
restartPolicy: OnFailure
volumes:
- name: script-dir
hostPath:
path: /path/to/my/script/dir
type: Directory
Example above shows how to use the hostPath type of volume in order to mount the script file.
Related
I have a small instance of influxdb running in my kubernetes cluster.
The data of that instance is stored in a persistent storage.
But I also want to run the backup command from influx at scheduled interval.
influxd backup -portable /backuppath
What I do now is exec into the pod and run it manually.
Is there a way that I can do this automatically?
You can consider running a CronJob with bitnami kubectl which will execute the backup command. This is the same as exec into the pod and run except now you automate it with CronJob.
CronJob is the way to go here. It acts more or less like a crontab, but for Kubernetes.
As an example you could use this
apiVersion: batch/v1
kind: CronJob
metadata:
name: backup
spec:
schedule: 0 8 * * *
jobTemplate:
spec:
template:
spec:
containers:
- name: influxdb-backup
image: influxdb
imagePullPolicy: IfNotPresent
command: ["/bin/sh"]
args:
- "-c"
- "influxd backup -portable /backuppath"
restartPolicy: Never
This will create a Job, everyday at 08:00, executing influxd backup -portable /backuppath. Of course, you have to edit it accordingly, to work on your environment.
This is the solution I have used for this question
apiVersion: v1
kind: ConfigMap
metadata:
name: cm-backupscript
namespace: influx
data:
backupscript.sh: |
#!/bin/bash
echo 'getting pod name'
podName=$(kubectl get pods -n influx --field-selector=status.phase==Running --output=jsonpath={.items..metadata.name})
echo $podName
#echo 'create backup'
kubectl exec -it $podName -n influx -- /mnt/influxBackupScript/influxbackup.sh
echo 'done'
---
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: backup-cron
namespace: influx
spec:
schedule: "0 2 * * *"
jobTemplate:
spec:
template:
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/arch
operator: In
values:
- amd64
volumes:
- name: backup-script
configMap:
name: cm-backupscript
defaultMode: 0777
containers:
- name: kubectl
image: bitnami/kubectl:latest
command:
- /bin/sh
- -c
- /mnt/scripts/backupscript.sh
volumeMounts:
- name: backup-script
mountPath: "/mnt/scripts"
restartPolicy: Never
You can either run it as a cronjob and setup the image to be able to connect to the DB, or you can sidecar it alongside your db pod, and set it to run the cron image (i.e. will run as a mostly-idle container in the same pod as your DB)
$ kubectl api-versions | grep batch
batch/v1
batch/v1beta1
When attempting to create this CronJob object which has a single container and an empty volume, I get this error:
$ kubectl apply -f test.yaml
error: error parsing test.yaml: error converting YAML to JSON: yaml: line 19: did not find expected key
The YAML
$ cat test.yaml
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: dummy
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: app
image: alpine
command:
- echo
- Hello World!
volumeMounts:
- mountPath: /data
name: foo
restartPolicy: OnFailure
volumes:
- name: foo
emptyDir: {}
Based on my reading of the API, I believe my schema is legit. Any ideas or help would be greatly appreciated.
I think it's indentation issue. Below yaml should work.
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: dummy
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: app
image: alpine
command:
- echo
- Hello World!
volumeMounts:
- mountPath: /data
name: foo
restartPolicy: OnFailure
volumes:
- name: foo
emptyDir: {}
I am trying to run a shell script at regular interval of 1 minute using a CronJob.
I have created following Cron job in my openshift template:
- kind: CronJob
apiVersion: batch/v2alpha1
metadata:
name: "${APPLICATION_NAME}"
spec:
schedule: "*/1 * * * *"
jobTemplate:
spec:
template:
spec:
containers:
- name: mycron-container
image: alpine:3
imagePullPolicy: IfNotPresent
command: [ "/bin/sh" ]
args: [ "/var/httpd-init/croyscript.sh" ]
volumeMounts:
- name: script
mountPath: "/var/httpd-init/"
volumes:
- name: script
configMap:
name: ${APPLICATION_NAME}-croyscript
restartPolicy: OnFailure
terminationGracePeriodSeconds: 0
concurrencyPolicy: Replace
The following is the configmap inserted as a volume in this job:
- kind: ConfigMap
apiVersion: v1
metadata:
name: ${APPLICATION_NAME}-croyscript
labels:
app: "${APPLICATION_NAME}"
data:
croyscript.sh: |
#!/bin/sh
if [ "${APPLICATION_PATH}" != "" ]; then
mkdir -p /var/httpd-resources/${APPLICATION_PATH}
fi
mkdir temp
cd temp
###### SOME CODE ######
This Cron job is running. as I can see the name of the job getting replaced every 1 min (as scheduled in my job). But it is not executing the shell script croyscript.sh
Am I doing anything wrong here? (Maybe I have inserted the configmap in a wrong way, so Job is not able to access the shell script)
Try below approach
Update permissions on configmap location
volumes:
- name: script
configMap:
name: ${APPLICATION_NAME}-croyscript
defaultMode: 0777
If this one doesnt work, most likely the script in mounted volume might have been with READONLY permissions.
use initContainer to copy the script to different location and set appropriate permissions and use that location in command parameter
I have trouble setting the result value of a shell script to arguments for Kubernetes Cronjob regularly.
Is there any good way to set the value refreshed everyday?
I use a Kubernetes cronjob in order to perform some daily task.
With the cronjob, a Rust application is launched and execute a batch process.
As one of arguments for the Rust app, I pass target date (yyyy-MM-dd formatted string) as a command-line argument.
Therefore, I tried to pass the date value into the definition yaml file for cronjob as follows.
And I try setting ${TARGET_DATE} value with following script.
In the sample.sh, the value for TARGET_DATE is exported.
cat sample.yml | envsubst | kubectl apply -f sample.sh
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: some-batch
namespace: some-namespace
spec:
schedule: "00 1 * * 1-5"
jobTemplate:
spec:
template:
spec:
containers:
- name: some-container
image: sample/some-image
command: ["./run"]
args: ["${TARGET_DATE}"]
restartPolicy: Never
I expected that this will create TARGET_DATE value everyday, but it does not change from the date I just set for the first time.
Is there any good way to set result of shell script into args of cronjob yaml regularly?
Thanks.
You can use init containers for that https://kubernetes.io/docs/concepts/workloads/pods/init-containers/
The idea is the following: you run your script that setting up this value inside init container, write this value into shared emptyDir volume. Then read this value from the main container. Here is example:
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: some-batch
namespace: some-namespace
spec:
schedule: "00 1 * * 1-5"
jobTemplate:
spec:
template:
spec:
initContainers:
- name: init-script
image: my-init-image
volumeMounts:
- name: date
mountPath: /date
command:
- sh
- -c
- "/my-script > /date/target-date.txt"
containers:
- name: some-container
image: sample/some-image
command: ["./run"]
args: ["${TARGET_DATE}"] # adjust this part to read from file
volumeMounts:
- name: date
mountPath: /date
restartPolicy: Never
volumes:
- name: date
emptyDir: {}
You can overwrite your docker entrypoint/ k8s container cmd and do this in one shot:
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: some-batch
namespace: some-namespace
spec:
schedule: "00 1 * * 1-5"
jobTemplate:
spec:
template:
spec:
containers:
- name: some-container
image: sample/some-image
command: ["/bin/sh"]
args:
- -c
- "./run ${TARGET_DATE}"
restartPolicy: Never
im running cron job in kubernetes, jobs completes successfully and i log output to log file inside(path: storage/logs) but i cannot access that file due to container is in completed here is my job yaml.
apiVersion: v1
items:
- apiVersion: batch/v1beta1
kind: CronJob
metadata:
labels:
chart: cronjobs-0.1.0
name: cron-cronjob1
namespace: default
spec:
concurrencyPolicy: Forbid
failedJobsHistoryLimit: 1
jobTemplate:
spec:
template:
metadata:
labels:
app: cron
cron: cronjob1
spec:
containers:
- args:
- /usr/local/bin/php
- -c
- /var/www/html/artisan bulk:import
env:
- name: DB_CONNECTION
value: postgres
- name: DB_HOST
value: postgres
- name: DB_PORT
value: "5432"
- name: DB_DATABASE
value: xxx
- name: DB_USERNAME
value: xxx
- name: DB_PASSWORD
value: xxxx
- name: APP_KEY
value: xxxxx
image: registry.xxxxx.com/xxxx:2ecb785-e927977
imagePullPolicy: IfNotPresent
name: cronjob1
ports:
- containerPort: 80
name: http
protocol: TCP
imagePullSecrets:
- name: xxxxx
restartPolicy: OnFailure
terminationGracePeriodSeconds: 30
schedule: '* * * * *'
successfulJobsHistoryLimit: 3
is there anyway i can get my log file content display on kubectl log command or other alternatives?
Cronjob runs pod according to the spec.schedule. After completing the task the pod's status will be set as completed, but the cronjob controller doesn't delete the pod after completing. And the log file content still there in the pod's container filesystem. So you need to do:
# here you can get the pod_name from the stdout of the cmd `kubectl get pods`
$ kubectl logs -f -n default <pod_name>
I guess you know that the pod is kept around as you have successfulJobsHistoryLimit: 3. Presumably your point is that your logging is going logged to a file and not stdout and so you don't see it with kubectl logs. If so maybe you could also log to stdout or put something into the job to log the content of the file at the end, for example in a PreStop hook.