Configuration Management with Environment Variable, Configmap & Secret

Configuration Management with Environment Variable, Configmap & Secret

Prerequisite

Complete Deploy application to openshift with s2i
Go to your project (same as your username)
Open Web Terminal by click '>_' on top of OpenShift Web Console
use web terminal to run command line

Environment Variable

You can set environment variables for containers running in a pod. Additionally, Kubernetes automatically exposes certain runtime information via environment variables.

Review Code, Check Environment Variable
- https://raw.githubusercontent.com/chatapazar/openshift-workshop/main/src/main/resources/application.properties
- In this properties, app.backend is url of backend service, we use this property for Rest Client
```
app.backend=https://httpbin.org/status/200
```
- test call backend service in web terminal console
```
curl -v https://httpbin.org/status/200
curl -v https://httpbin.org/status/400
```

Check Current Environment, Test with below command

  BACKEND_URL=https://$(oc get route backend -o jsonpath='{.spec.host}')
  curl $BACKEND_URL/backend

sample output, see Response:200

  Backend version:v1, Response:200, Host:backend-56957dcc4f-t9bpf, Status:200, Message: Hello, World

Change Environment Variable, From Topology, click Duke icon (backend deployment), backend link in side panel (click link at 'D backend')
select Environment tab,
in single values(env), input name: 'app.backend' and value: 'https://httpbin.org/status/400', clicke save
wait until openshift redeploy backend success

back to web terminal, test call backend again

BACKEND_URL=https://$(oc get route backend -o jsonpath='{.spec.host}')
curl $BACKEND_URL/backend

check output change, Response:400

Backend version:v1, Response:400, Host:backend-6cf95f994d-cgxsb, Status:400, Message: Hello, World

Configmag

Many applications require configuration using some combination of configuration files, command line arguments, and environment variables. These configuration artifacts should be decoupled from image content in order to keep containerized applications portable.

The ConfigMap object provides mechanisms to inject containers with configuration data while keeping containers agnostic of OpenShift Container Platform. A ConfigMap can be used to store fine-grained information like individual properties or coarse-grained information like entire configuration files or JSON blobs.

create example ConfigMap, click ConfigMaps at left menu, click Create ConfigMap

Create ConfigMap with YAML, copy below yaml to editor, click create

Remark: change namespace to your username

apiVersion: v1
kind: ConfigMap
metadata:
name: example
namespace: <user user name>
data:
app.backend.200: https://httpbin.org/status/200
app.backend.400: https://httpbin.org/status/400

Review configmap 'example' value in data section
back to Topology, click Duke icon (backend deployment), backend link in side panel (click link at 'D backend'), click Environment Tab
remove old app.backend environment variable
click 'Add from ConfigMap or Secret', set name: 'app.backend', value: 'CM example' and key: 'app.backend.200'
click save, and wait until backend redeploy complete

back to web terminal, test call backend again

BACKEND_URL=https://$(oc get route backend -o jsonpath='{.spec.host}')
curl $BACKEND_URL/backend

check output change, Response:200

Backend version:v1, Response:200, Host:backend-95647fbb8-2xql7, Status:200, Message: Hello, World

Secret

The Secret object type provides a mechanism to hold sensitive information such as passwords, OpenShift Container Platform client configuration files, dockercfg files, private source repository credentials, and so on. Secrets decouple sensitive content from the pods. You can mount secrets into containers using a volume plug-in or the system can use secrets to perform actions on behalf of a pod.

at web terminal, test curret value of secret message : 'Not Found Secret'

curl $BACKEND_URL/backend/showsecret

example result

Backend version:v1, Response:200, Host:backend-95647fbb8-62584, Status:200, Message: Not Found Secret

click Secrets from left menu
select create with key/value secret
in create key/value secret page, set secret name: example, key: 'app.secretMessage', value: 'Hi! World of Quarkus!', click Create
check in secret 'example', in data section, show 'app.secretMessage' and value with encryption (you can click copy and paste in your editor to view message)
back to Topology, click Duke icon (backend deployment), backend link in side panel (click link at 'D backend'), click Environment Tab
click 'Add from ConfigMap or Secret', set name: 'app.secretMessage', value: 'S example' and key: 'app.secretMessage'
click save, wait until backend redeploy complete

Re-Test showsecret api again

curl $BACKEND_URL/backend/showsecret

example result

Backend version:v1, Response:200, Host:backend-5bc95899d-tdmv5, Status:200, Message: Hi! World of Quarkus!

Next Step

Application Health check

App Configuration