KUBERNETES( Commands , Arguments and ENV variables)

In this below sample yaml file- command & arguments values are executed during the container startup.

SAMPLE YAML Showing the Usage Command & Argument.

sample-yaml

Passing just and argument to overwrite the default value:

SAMPLE YAML showing the usage of Argument:

sample-arg-yaml

ENV Variable:

In kubernetes to set and environment variable we can use env property.

There are different way to sett the environment variable.

- Plain Key value:

env:
  -name: Color
   value: green

- ConfigMap

env:
  -name: Color
   valueFrom:
     configMapKeyRef:

- Secrets :

Secret are used to store the sensitive information like- password , keys etc. They are stored in encoded or Hashed format.

Steps involved- 1.) Create a secret. 2.) Inject into to pod.

Two ways to create a Secret —

1.) Imperative way without using a definition file :-

syntax: kubectl create secret generic <secret name> — from-leteral=<Key> =<Value>

kubectl create secret generic app-secret — from-literal=DB_HOST=OracleServer

— from-literal=DB_USER=OracleUser

Create from file:

kubectl create secret generic <secret-name> — from-file=<path-to-file>

kubectl create secret generic app-secret — from-file=app_secret.properties

2.) Declarative way by using a secret definition file.

syntax: kubectl create -f

env:
  -name: Color
   valueFrom:
     secretKeyRef:
=================================
secret1.yaml:
apiVersion: v1
kind: Secret
metadata:
  name: app-secret
data:
  DB_USER: jdw82js=$
  DB_PASS: GFcCd674k
=================================
Pod-defn.yaml:
apiVersion: v1
kind: Pod
metadata:
  name: app1
  labels:
     name: app1
spec:
  containers:
  - name: app1
    image: app1
    ports:
      -containerPort: 8080
    envFrom:
      -secretRef:
           name: app-secret