Question 121504 in Redis Question posted in
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loading codes to redis from pod definition file

I have kubernetes job defined as following:

apiVersion: batch/v1
kind: Job
metadata:
  name: redis-master
  namespace: sandbox
  labels:
    app: redis
spec:
  parallelism: 1
  ttlSecondsAfterFinished: 10
  template:
    metadata:
      labels:
        app: redis
    spec:
      containers:
        - name: master
          image: redis
          command: ["sh", "-c"]

          args:
          - redis-server
          - sleep 10
          - redis-cli RPUSH codes $(cat /data/codes)
          env:
            - name: MASTER
              value: "true"
          ports:
            - containerPort: 6379
          volumeMounts:
            - name: codes
              mountPath: /data/codes
              subPath: codes
              readOnly: true
      volumes:
        - name: codes
          configMap:
            name: codes
      restartPolicy: Never

when pod is up and running redis is empty:

/deploy/base$ kubectl exec -it -n box redis-master-mbhrk -- /bin/sh
# redis-cli lrange codes 0 -1
(empty array)
#

this pod should kill him self when the queue codes is empty.

also, i get an error in pod console

can't access tty; job control turned off

how can I load a codes to redis ???

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    The issue was in

    args:
  - redis-server
  - sleep 10

    Command redis-server is command which brings redis server up. So next command can not be executed because redis-server is still running.


  2. 0

    A container only runs one command. You’ve set that command to /bin/sh -c and passed it a command string to run (redis-server), along with two additional parameters which would be visible inside that command string as $0 and $1.

    The first thing you need to do is split the Redis server proper into a separate container, probably managed by a StatefulSet (or perhaps a Deployment if persistence is disabled). You might use something like a prepackaged Helm chart to simplify deploying this. We’ll assume this already exists:

    apiVersion: v1
kind: Service
metadata:
  name: redis-server
...

    Now your Job needs to only run the redis-cli RPUSH command. Because of the way you use a command substitution, you do need a shell here. However, since you’re not running the Redis server here, you don’t need various bits of machinery around that.

    You could probably write the Job as:

    apiVersion: batch/v1
kind: Job
metadata:
  name: load-codes
  namespace: sandbox
  # labels:
  #   app: redis
spec:
  template:
    # metadata:
    #   labels:
    #     app: redis
    spec:
      containers:
        - name: loader
          image: redis
          command: 
            - /bin/sh
            - -c
            - redis-cli -h redis-server RPUSH codes $(cat /data/codes)
          volumeMounts:
            - name: codes
              mountPath: /data
              readOnly: true
      volumes:
        - name: codes
          configMap:
            name: codes
      restartPolicy: OnFailure

    You’ll probably need to set the labels so that they’re not picked up by the main Service (since the pod isn’t running a Redis server). I’ve also set the restart policy to OnFailure: if the pod does fail for some reason, maybe because the Redis server isn’t available yet, this will automatically restart it, but if it succeeds, the Job will be marked "completed".

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