How to include script and run it into kubernetes yaml?

Question

It is how to run simple batch in kubernetes yaml (helloworld.yaml):

...
image: "ubuntu:14.04"
command: ["/bin/echo", "hello", "world"]
...

In Kubernetes i can deploy that like this:

$ kubectl create -f helloworld.yaml

Suppose i have a batch script like this (script.sh):

#!/bin/bash
echo "Please wait....";
sleep 5

Is there way to include the script.sh into kubectl create -f so it can run the script. Suppose now helloworld.yaml edited like this:

...
image: "ubuntu:14.04"
command: ["/bin/bash", "./script.sh"]
...

Weswesa

Answer 1

I'm using this approach in OpenShift, so it should be applicable in Kubernetes as well.

Try to put your script into a configmap key/value, mount this configmap as a volume and run the script from the volume.

apiVersion: batch/v1
kind: Job
metadata:
  name: hello-world-job
spec:
  parallelism: 1    
  completions: 1    
  template:         
    metadata:
      name: hello-world-job
    spec:
      volumes:
      - name: hello-world-scripts-volume
        configMap:
          name: hello-world-scripts
      containers:
      - name: hello-world-job
        image: alpine
        volumeMounts:
          - mountPath: /hello-world-scripts
            name: hello-world-scripts-volume
        env:
          - name: HOME
            value: /tmp
        command:
        - /bin/sh
        - -c
        - |
          echo "scripts in /hello-world-scripts"
          ls -lh /hello-world-scripts
          echo "copy scripts to /tmp"
          cp /hello-world-scripts/*.sh /tmp
          echo "apply 'chmod +x' to /tmp/*.sh"
          chmod +x /tmp/*.sh
          echo "execute script-one.sh now"
          /tmp/script-one.sh
      restartPolicy: Never
---
apiVersion: v1
items:
- apiVersion: v1
  data:
    script-one.sh: |
      echo "script-one.sh"
      date
      sleep 1
      echo "run /tmp/script-2.sh now"
      /tmp/script-2.sh
    script-2.sh: |
      echo "script-2.sh"
      sleep 1
      date
  kind: ConfigMap
  metadata:
    creationTimestamp: null
    name:  hello-world-scripts
kind: List
metadata: {}

Lienlienhard

I just want to stress the importance of restartPolicy: Never, because otherwise you might get CrashLoopBackOffs. See here. – Esmond

Hey @Esmond thanks for the comment. My doubt is what happens if we set the restartPolicy: Never and our script fails due to some error? – Amblyopia

can we bash over shell in pod – Coonskin

Is there a need to use the list object? I was able to use multiple scripts and execute them as specified in the answer using a deployment without using list. But i am not able to figure out why list was used in the answer. Can anyone help please – Yaupon

Why do we get the CrashLoopBackOff if we do not define the restartPolicy? – Tor

Answer 2

As explained here, you could use the defaultMode: 0777 property as well, an example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: test-script
data:
  test.sh: |
    echo "test1"
    ls
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: test
spec:
  selector:
    matchLabels:
      app: test
  template:
    metadata:
      labels:
        app: test
    spec:
      volumes:
      - name: test-script
        configMap:
          name: test-script
          defaultMode: 0777
      containers:
      - command:
        - sleep
        - infinity
        image: ubuntu
        name: locust
        volumeMounts:
          - mountPath: /test-script
            name: test-script

You can enter into the container shell and execute the script /test-script/test.sh

Alialia

Nice example; defaultMode or fsGroup is required to have the required permissions to run the script – Flossi

You save my day!!! – Athens

when i add default mode as 0755, still my configmap has the 777 permission. lrwxrwxrwx 1 root root 22 Aug 16 19:31 parameters.conf -> ..data/parameters.conf – Drugge