Container doesn't recognize configmap values passed as env vars

Question

I have created a configMap from a file using "kustomize", then i am passing the key/value pairs from the configMap to the container as environment variables, when i EXEC into the container and write "env" the pairs seem to show up, but when i try to access one of them like "echo $VARNEM", nothing shows up.

first i wrote this test 'config1.properties' file

JIN=bombay
RUM=bacardi
WHISKY=jhonny walker

then i converted it to a configMap using kustomize

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - k8s.yaml
configMapGenerator:
- name: map1
  files:
  - config1.properties

then i converted the map to environment variables in the deployment file (this is under the 'container' section)

          env:
            - name: map-envs
              valueFrom:
                configMapKeyRef:
                  name: map1-kt62t9247m
                  key: config1.properties

finally when i EXEC into the container, it does show up, additionally this is how it shows on the cluster tree

but when i try to access the var, it shows as null, so as for my node.js app when i try to reach it from there.

I think it's something about the whole config file being treated as a key of the 'map1-kt62t9247m' but i haven't managed to fixed it by myself.

Answer 1

Your existing kustomization.yaml file results in this ConfigMap:

apiVersion: v1
data:
  config1.properties: |
    JIN=bombay
    RUM=bacardi
    WHISKY=jhonny walker
kind: ConfigMap
metadata:
  name: map1-24h4mcf5gh

That is, there is a single key -- config1.properties -- and the value is the contents of the config1.properties file.

If you want each of the properties in config1.properties to be exposed as a key in the ConfigMap, then you need to tell Kustomize that this file contains a list of environment variable by using the envs keyword instead of files:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - k8s.yaml

configMapGenerator:
  - name: map1
    envs:
      - config1.properties

This produces:

apiVersion: v1
data:
  JIN: bombay
  RUM: bacardi
  WHISKY: jhonny walker
kind: ConfigMap
metadata:
  name: map1-6b95d4kbkm

(There are examples of this in the documentation.)

Then we need to use an envFrom directive in our Pod template, rather than setting a single environment variable as you are are currently doing:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: example
  name: example
spec:
  replicas: 1
  selector:
    matchLabels:
      app: example
  template:
    metadata:
      labels:
        app: example
    spec:
      containers:
      - envFrom:
        - configMapRef:
            name: map1-6b95d4kbkm
        image: docker.io/alpinelinux/darkhttpd
        name: example

Once our Pod is running, we see:

/ $ env
JIN=bombay
RUM=bacardi
WHISKY=jhonny walker
.
.
.