K8s Trivial Questions

K8s
20

Here are some examples or illustrations that I use quite a lot in my work routine.

How to reuse env parameter in another one(e.g. assemble many into one)

That's quite useful for database DSN configuration like work cases.

apiVersion: v1
kind: Pod
metadata:
  name: mysql-app
spec:
  containers:
  - name: mysql-container
    image: mysql:5.7
    env:
    - name: mysql_host
      value: "mysql.default.svc.cluster.local"
    - name: mysql_db
      value: "myapp"
    - name: mysql_port
      value: "3306"
    - name: PROTOCOL
      value: "mysql"
    - name: mysql_dsn
      value: "$(PROTOCOL)://$(mysql_host):$(mysql_port)/$(mysql_db)"

Why my kustomization replaced my base envFrom?

You can find detail K8s Definition from here. If there's no other notes about the patch strategy and patch merge key, that means the key is entirely replaced by the overlays one against the base, e.g. env from deployment will be merged along with the overlays but not the envFrom.