K8S deployments with shared environment variables

You can create a ConfigMap with all the common kye:value pairs of env variables.

Then you can reuse the configmap to declare all the values of configMap as environment in Deployment.

Here is an example taken from kubernetes official docs.

Create a ConfigMap containing multiple key-value pairs.

apiVersion: v1kind: ConfigMapmetadata:  name: special-config  namespace: defaultdata:  SPECIAL_LEVEL: very  SPECIAL_TYPE: charm

Use envFrom to define all of the ConfigMap’s data as Pod environment variables. The key from the ConfigMap becomes the environment variable name in the Pod.

apiVersion: v1kind: Podmetadata:  name: test-podspec:  containers:    - name: test-container      image: k8s.gcr.io/busybox      command: [ "/bin/sh", "-c", "env" ]      envFrom:      - configMapRef:          name: special-config # All the key-value pair will be taken as environment key-value pair      env:      - name: uncommon        value: "uncommon value"  restartPolicy: Never

You can specify uncommon env variables in env field.

Now, to verify if the environment variables are actually available, see the logs.

$ kubectl logs -f test-pod KUBERNETES_PORT=tcp://10.96.0.1:443SPECIAL_LEVEL=veryuncommon=uncommon valueSPECIAL_TYPE=charm...

Here, it is visible that all the provided environments are available.

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

apiVersion: apps/v1kind: Deploymentmetadata:  name: auth-deplspec:  replicas: 1  selector:    matchLabels:      app: auth  template:    metadata:      labels:        app: auth    spec:      containers:        - name: auth          image: lord/auth          resources:            requests:              memory: "128Mi"              cpu: "250m"            limits:              memory: "256Mi"              cpu: "500m"          env:            - name: JWT_KEY              valueFrom:                secretKeyRef:                  name: jwt-secret                  key: JWT_KEY

 process.env.JWT_KEY

apiVersion: apps/v1kind: Deploymentmetadata:  name: tickets-deplspec:  replicas: 1  selector:    matchLabels:      app: tickets  template:    metadata:      labels:        app: tickets    spec:      containers:        - name: tickets          image: lord/tickets          resources:            requests:              memory: "128Mi"              cpu: "250m"            limits:              memory: "256Mi"              cpu: "500m"          env:            - name: JWT_KEY              valueFrom:                secretKeyRef:                  name: jwt-secret                  key: JWT_KEY

 process.env.JWT_KEY