How to pass docker container flags via kubernetes pod

Question

Hi I am running kubernetes cluster where I run mailhog container.

But I need to run it with own docker run parameter. If I would run it in docker directly. I would use command:

docker run  mailhog/mailhog -auth-file=./auth.file

But I need to run it via Kubernetes pod. My pod looks like:

   apiVersion: extensions/v1beta1
    kind: Deployment
    metadata:
      name: mailhog
    spec:
      replicas: 1
      revisionHistoryLimit: 1
      strategy:
          type: RollingUpdate
      template:
        metadata:
          labels:
            app: mailhog
        spec:
          containers:
          - name: mailhog
            image: us.gcr.io/com/mailhog:1.0.0
            ports:
            - containerPort: 8025

How to achieve to run Docker container with parameter -auth-file=./auth.file via kubernetes. Thanks.

I tried adding under containers

        command: ["-auth-file", "/data/mailhog/auth.file"]

but then I get

 Failed to start container with docker id 7565654 with error: Error response from daemon: Container command '-auth-file' not found or does not exist.

score 27 · Accepted Answer · answered May 23 '17 at 08:25

thanks to @lang2

here is my deployment.yaml:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: mailhog
spec:
  replicas: 1
  revisionHistoryLimit: 1
  strategy:
      type: RollingUpdate
  template:
    metadata:
      labels:
        app: mailhog
    spec:
      volumes:
      - name: secrets-volume
        secret:
            secretName: mailhog-login
      containers:
      - name: mailhog
        image: us.gcr.io/com/mailhog:1.0.0
        resources:
          limits:
            cpu: 70m
            memory: 30Mi
          requests:
            cpu: 50m
            memory: 20Mi
        volumeMounts:
        - name: secrets-volume
          mountPath: /data/mailhog
          readOnly: true
        ports:
        - containerPort: 8025
        - containerPort: 1025
        args:
          - "-auth-file=/data/mailhog/auth.file"

score 10 · Answer 2 · edited Feb 01 '21 at 13:50

10

In kubernetes, command is equivalent of ENTRYPOINT. In your case, args should be used.

https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.19/#container-v1-core

edited Feb 01 '21 at 13:50

Paul Razvan Berg

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answered May 22 '17 at 01:51

lang2

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This link seems to be dead. – Didier Aupest Aug 28 '19 at 07:48

Janos Lenart · Answer 3 · 2017-05-21T15:17:26.677

9

You are on the right track. It's just that you also need to include the name of the binary in the command array as the first element. You can find that out by looking in the respective Dockerfile (CMD and/or ENTRYPOINT).

In this case: command: ["Mailhog", "-auth-file", "/data/mailhog/auth.file"]

edited May 21 '17 at 15:17

answered May 21 '17 at 15:03

Janos Lenart

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score 2 · Answer 4 · answered Jul 02 '20 at 12:40

I needed similar task (my aim was passing the application profile to app) and what I did is the following:

Setting an environment variable in Deployment section of the kubernetes yml file.

env:
- name: PROFILE
  value: "dev"

Using this environment variable in dockerfile as command line argument.

CMD java -jar -Dspring.profiles.active=${PROFILE} /opt/app/xyz-service-*.jar

How to pass docker container flags via kubernetes pod

4 Answers4

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