For Kubernetes deployment in which file should I keep my environment variables, docker-compose.yml or *-deployment.yaml?

For Kubernetes deployment in which file should I keep my environment variables, docker-compose.yml or *-deployment.yaml?

I read that we pass environment variables (like LOG_LEVEL=development npm run start) in the docker-compose file but I also saw the environment variable values assigned in *-deployment.yaml as well.

In docker-compose.yml I see environment variables under the 'environment' tag

environment:
      NODE_ENV: development
      LOG_LEVEL: debug

while in *-deployment.yaml I see the same environment variables under the 'env' tag like

env:
	- name: NODE_ENV
	  value: 'production'
	- name: LOG_LEVEL
	  value: 'info'

I want to know

1. Do I need to assign value to an environment variable in both files? and if not
2. In which file I should write my variables and which approach is better?

Am not really sure what docker-compose.yaml has to do with Kubernetes, I think the environment of docker-compse` is to be used with docker-compose as a local setup, which is separated from Kubernetes which should be used with deployment

but you can use configMap with Kubernetes. A ConfigMap is an API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume

For example, postgres-config.yaml file for postgres configuration

apiVersion: v1
kind: ConfigMap
metadata:
  name: postgres-config
  labels:
    app: postgres
data:
  POSTGRES_DB: postgresdb
  POSTGRES_USER: admin
  POSTGRES_PASSWORD: psltest

Then you can apply the file like

kubectl apply -f postgres-config.yaml 

And this can be used in all the *-deployment.yaml using envFrom

envFrom:
   - configMapRef:
      name: postgres-config

For more information about ConfigMap Check here