How to create an environment variable in kubernetes container

Question

I am trying to pass an environment variable in kubernetes container.

What have I done so far ?

Create a deployment

kubectl create deployment foo --image=foo:v1
Create a NODEPORT service and expose the port

kubectl expose deployment/foo --type=NodePort --port=9000
See the pods

kubectl get pods
dump the configurations (so to add the environment variable)

kubectl get deployments -o yaml > dev/deployment.yaml

kubectl get svc -o yaml > dev/services.yaml

kubectl get pods -o yaml > dev/pods.yaml
Add env variable to the pods env:
- name: FOO_KEY value: "Hellooooo"
Delete the svc,pods,deployments

kubectl delete -f dev/ --recursive
Apply the configuration

kubectl apply -f dev/ --recursive
Verify env parameters

kubectl describe pods

Something weird

If I manually changed the meta information of the pod yaml and hard code the name of the pod. It gets the env variable. However, this time two pods come up one with the hard coded name and other with the hash with it. For example, if the name I hardcoded was "foo", two pods namely foo and foo-12314faf (example) would appear in "kubectl get pods". Can you explain why ?

Question

Why does the verification step does not show the environment variable ?

Hi, Could you verify the variable inside the deployment yaml? — Suresh Vishnoi, Sep 21 '19 at 14:36
you should mutate deployment, it's not good idea to directly mutate pods if is created by deployment — Suresh Vishnoi, Sep 21 '19 at 14:37
I added the env variable inside pod yaml file. I didn't know if they can be passed in the deployment as well. Is it ? — cafebabe1991, Sep 21 '19 at 14:43
and No. The variable is not present in the output of the command you wrote. — cafebabe1991, Sep 21 '19 at 14:46
btw `env` will come under containers, not in pod. where exactly are you adding the environment variable ? — Suresh Vishnoi, Sep 21 '19 at 14:50
I saw that env can also be given under kind: Pod as well. Anyways, declaring the env in the deployment yaml works. Thanks for the suggestion. — cafebabe1991, Sep 21 '19 at 14:51
podSpec is composed by replicaSet which is also composed by deployment. — Suresh Vishnoi, Sep 21 '19 at 14:52
Here is a link to the documentation that says it can be inside the pod section too https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#use-configmap-defined-environment-variables-in-pod-commands — cafebabe1991, Sep 21 '19 at 14:53

Suresh Vishnoi · Accepted Answer · 2019-09-21T19:10:45.850

4

As the issue is resolved in the comment section.

If you want to set env to pods I would suggust you to use set sub commend

kubectl set env --help will provide more detail such as list the env and create new one

Examples:
  # Update deployment 'registry' with a new environment variable
  kubectl set env deployment/registry STORAGE_DIR=/local

  # List the environment variables defined on a deployments 'sample-build'
  kubectl set env deployment/sample-build --list

Deployment enables declarative updates for Pods and ReplicaSets. Pods are not typically directly launched on a cluster. Instead, pods are usually managed by replicaSet which is managed by deployment.

following thread discuss what-is-the-difference-between-a-pod-and-a-deployment

edited Sep 21 '19 at 19:10

answered Sep 21 '19 at 15:02

Suresh Vishnoi

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Can you also clarify why was the env variable not working when it was added to the pod spec directly ? I have added details about this in my question. Please acknowledge that too. – cafebabe1991 Sep 21 '19 at 17:57
I do not know what exactly, you are trying. nevertheless, I updated my answer with more description to list, add or delete the env variable on deployment. – Suresh Vishnoi Sep 21 '19 at 19:12
1

I guess I didn't k8s much back then. Now the question I asked sounds funny. Accepting it now – cafebabe1991 May 02 '21 at 15:18

Rafiq · Answer 2 · 2021-05-03T12:22:03.333

You can add any number of env vars into your deployment file

spec:
      containers:
        - name: auth
          image: lord/auth
          env:
            - name: MONGO_URI
              value: "mongodb://auth-mongo-srv:27017/auth"

 process.env.MONGO_URI

or you can add a secret first then use newly created secret into your countless deployment files to share same environment variable with value:

kubectl create secret generic jwt-secret --from-literal=JWT_KEY=my_awesome_jwt_secret_code

spec:
      containers:
        - name: auth
          image: lord/auth
          env:
            - name: MONGO_URI
              value: "mongodb://auth-mongo-srv:27017/auth"
            - name: JWT_KEY
              valueFrom:
                secretKeyRef:
                  name: jwt-secret
                  key: JWT_KEY

 process.env.MONGO_URI
 process.env.JWT_KEY

How to create an environment variable in kubernetes container

2 Answers2