Can we have same kind of multiple containers in a Pod in Kubernetes?

Question

For instance can I have following yaml to produce a pod with multiple containers:

apiVersion: v1
kind: Pod
metadata:
name: lampapp
labels:
    app: app
spec:
  containers:
  - name: lampdb
    image: mysql_test
  - name: app
    image: php-app-db-url-env
    env:
     - name: DB_URL
      value: 127.0.0.1:3306
  - name: app2
    image: php-app-db-url-env
    env:
    - name: DB_URL
      value: 127.0.0.1:3306

Elisavetpol

Check this to better understand how to write a spec file: cloud.google.com/container-engine/docs/spec-schema – Rubie

@Rubie Link is now broken. Gotta love chasing Google and their ever-out-of-date docs! – Aisha

The latest docs are here now: kubernetes.io/docs/api-reference/v1.5 . Change the "1.5" with the desired version of your kube cluster. – Rubie

Answer 1

Yes, you can add multiple container with same image.

The containers object must contain:

1. name: Name of the container. It must be a DNS_LABEL and be unique within the pod. Cannot be updated.
2. image: Docker image name.

You have to make container name unique

You can do following:

- name: app
  image: php-app-db-url-env   ---
- name: app2                    |> same image
  image: php-app-db-url-env   ---

But not this one:

- name: app
  image: php-app-db-url-env
- name: app
  image: <any image>

Also the containers spec should include a unique port number within the Pod

Cockchafer

Thanks. I tried above structure but what it did was : it ups the first container but terminates the second one in few seconds. And it keeps on restarting it. – Elisavetpol

May be they are trying to listen same port.. Check that – Cockchafer

kubectl describe should give you a clue as to what is going wrong – Informer

Answer 2

Same of kind of containers can be there but then their port would be different.

Elisavetpol

Yes, its a good remark. If you have 2 containers with the same image and different names be careful with the containers params. If containers would be have the same port options only the last one container would be running. – Urion

Answer 3

Well, that's exactly what a pod is: multiple containers that share some namespaces and volumes.

Rubie