Kubernetes/Openshift: how to use envFile to read from a filesystem file - kubernetes

Question

I've configured two container into a pod.
The first of them is engaged to create a file like:
SPRING_DATASOURCE_USERNAME: username
SPRING_DATASOURCE_PASSWORD: password
I want that the second container reads from this location in order to initialize its env variables.
I'm using envFrom but I don't quite figure out how to use it.
This is my spec:
metadata:
annotations:
configmap.fabric8.io/update-on-change: ${project.artifactId}
labels:
name: wsec
name: wsec
spec:
replicas: 1
selector:
name: wsec
version: ${project.version}
provider: fabric8
template:
metadata:
labels:
name: wsec
version: ${project.version}
provider: fabric8
spec:
containers:
- name: sidekick
image: quay.io/ukhomeofficedigital/vault-sidekick:latest
args:
- -cn=secret:openshift/postgresql:env=USERNAME
env:
- name: VAULT_ADDR
value: "https://vault.vault-sidekick.svc:8200"
- name: VAULT_TOKEN
value: "34f8e679-3fbd-77b4-5de9-68b99217cc02"
volumeMounts:
- name: sidekick-backend-volume
mountPath: /etc/secrets
readOnly: false
- name: wsec
image: ${docker.image}
env:
- name: SPRING_APPLICATION_JSON
valueFrom:
configMapKeyRef:
name: wsec-configmap
key: SPRING_APPLICATION_JSON
envFrom:
???
volumes:
- name: sidekick-backend-volume
emptyDir: {}

Answer 1

It looks like you are packaging the environment variables with the first container and read then in the second container.
If that's the case, you can use initContainers.
Create a volume mapped to an emptyDir. Mount that on the initContainer(propertiesContainer) and the main container(springBootAppContainer) as a volumeMount. This directory is now visible to both containers.
image: properties/container/path
command: [bash, -c]
args: ["cp -r /location/in/properties/container /propsdir"]
volumeMounts:
- name: propsDir
mountPath: /propsdir
This will put the properties in /propsdir. When the main container starts, it can read properties from /propsdir