Kubernetes ConfigMap

FROM node:21-slim
EXPOSE 8000
COPY runapp.js .
CMD node runapp.js

# node21 이미지에
# 8000 port 개방하고
# 현재 폴더에서 runapp.js 카피
# 그 파일을 실행

var http = require('http');
const apiKey = process.env.API_KEY;
if (!apiKey) {
        console.log('API_KEY is not set in the environment variables.');
        http.createServer(function (req, res) {
                res.setHeader('Content-Type', 'text/plain');
                res.end("API_KEY is not set in the environment variables." + "\n");
        }).listen(8000);
} else {
        console.log('API_KEY:', apiKey);
        http.createServer(function (req, res) {
                res.setHeader('Content-Type', 'text/plain');
                res.end("Welcome to ConfigMap Kubernetes" + "\n");
        }).listen(8000);
}
// 환경변수에서 API_KEY 있는지 확인하여 결과물 다르게 표출

$ docker build -t crimsonpinus/configmaptest:latest --nocache .
# Dockerfile 빌드

$ docker run -d --name nodetest -p 8000:8000 crimsonpinus/configmaptest

$ curl localhost:8000
API_KEY is not set in the environment variables.

$ docker stop nodetest

$ docker rm nodetest

$ docker run -d --name nodetest -e API_KEY hello -p 8000:8000 crimsonpinus/configmaptest

$ curl localhost:8000
Welcome to ConfigMap Kubernetes

# kubernetes에서 사용하기 위해 본인의 계정에 업로드
$ docker push crimsonpinus/configmaptest:latest

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: cmtest-pod
  name: cmtest-pod
spec:
  containers:
  - image: crimsonpinus/configmaptest
    name: cmtest-pod
    ports:
    - containerPort: 8000
    envFrom:
    - configMapRef:
        name: api-key
# cm-test-pod 생성후 위 envFrom 부분 추가

$ kubectl edit cm api-key
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
data:
  API_KEY: k8scm-edit  # 값 변경
kind: ConfigMap
metadata:
  creationTimestamp: "2024-04-12T04:56:56Z"
  name: api-key
  namespace: default
  resourceVersion: "1320379"
  uid: 56d43ca7-3a6e-47b7-ab6a-1460a0725bc7

$ kubectl exec -it cmtest-pod -- env | grep -i api
API_KEY=k8scm
# 변경 안되었음

# 강제 재시작
$ kubectl replace --force -f ./cmtest-pod.yaml
pod "cmtest-pod" deleted
pod/cmtest-pod replaced

$ kubectl exec -it cmtest-pod -- env | grep -i api
API_KEY=k8scm-edit

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-configmap
data:
  string-value: "Hello, world!"  # 스트링 형식, 공백이 없으면 따옴표 없어도 됨
  number-value: "42"             # 숫자 형식
  boolean-value: "true"         # 불린 타입은 따옴표 무조건 필요
  multiline-value: |            # | 표시는 아래 줄과 이어진다는 표시
    This is a multiline value
    that spans multiple lines
  list-value: |
    - item1
    - item2
    - item3
  object-value: |
    key1: value1
    key2: value2
  json-value: |-
    {
      "key": "value",
      "array": [1, 2, 3],
      "nested": {
        "innerKey": "innerValue"
      }
    }
  yaml-value: |-
    key: value
    array:
      - 1
      - 2
      - 3

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: cm-volume-pod
  name: cm-volume-pod
spec:
  containers:
  - image: nginx:1.25.3-alpine
    name: cm-volume-pod
    ports:
    - containerPort: 80
    volumeMounts:
    - name: cm-volume
      mountPath: /etc/config
  volumes:
  - name: cm-volume
    configMap:
      name: k8s-env
      key: orchestrator  # key를 이용하여 일부의 값만 가져올 수 있음

$ kubectl apply -f cm-volume-pod.yaml
pod/cm-volume-pod created

$ kubectl get po,svc -o wide | grep cm
pod/cm-volume-pod                       1/1     Running   0          31s     10.109.131.17   k8s-node2    <none>           <none>

$ kubectl exec cm-volume-pod -- ls -la /etc/config
total 0
drwxrwxrwx    3 root     root            95 Apr 12 06:11 .
drwxr-xr-x    1 root     root            52 Apr 12 06:11 ..
drwxr-xr-x    2 root     root            41 Apr 12 06:11 ..2024_04_12_06_11_12.4261600263
lrwxrwxrwx    1 root     root            32 Apr 12 06:11 ..data -> ..2024_04_12_06_11_12.4261600263
lrwxrwxrwx    1 root     root            19 Apr 12 06:11 orchestrator -> ..data/orchestrator
lrwxrwxrwx    1 root     root            14 Apr 12 06:11 runtime -> ..data/runtime

$ kubectl exec cm-volume-pod -- cat /etc/config/orchestrator
kubernetes

$ kubectl edit cm k8s-env
# orchestrator: k8s 로 변경

# nginx 리로드
$ kubectl exec cm-volume-pod -- nginx -s reload
2024/04/12 06:18:19 [notice] 46#46: signal process started

$ kubectl exec cm-volume-pod -- cat /etc/config/orchestrator
k8s

REDIS_PRIMARY_SERVICE_HOST=10.0.0.11
REDIS_PRIMARY_SERVICE_PORT=6379
REDIS_PRIMARY_PORT=tcp://10.0.0.11:6379
REDIS_PRIMARY_PORT_6379_TCP=tcp://10.0.0.11:6379
REDIS_PRIMARY_PORT_6379_TCP_PROTO=tcp
REDIS_PRIMARY_PORT_6379_TCP_PORT=6379
REDIS_PRIMARY_PORT_6379_TCP_ADDR=10.0.0.11

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: cmfile-volume-pod
  name: cmfile-volume-pod
spec:
  containers:
  - image: nginx:1.25.3-alpine
    name: cmfile-volume-pod
    ports:
    - containerPort: 80
    volumeMounts:
    - name: redis-volume
      mountPath: /opt/redis/config
  volumes:
  - name: redis-volume
    configMap:
      name: redis-config
# 녹색 부분 추가

$ kubectl create cm redis-config --from-file=redis.conf
configmap/redis-config created

$ kubectl get cm
NAME                         DATA   AGE
k8s-env                      2      30m
kube-root-ca.crt             1      7d22h
kubeshark-config-map         22     7d17h
kubeshark-nginx-config-map   1      7d17h
redis-config                 1      9s

$ kubectl describe cm redis-config
Name:         redis-config
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
redis.conf:
----
REDIS_PRIMARY_SERVICE_HOST=10.0.0.11
REDIS_PRIMARY_SERVICE_PORT=6379
REDIS_PRIMARY_PORT=tcp://10.0.0.11:6379
REDIS_PRIMARY_PORT_6379_TCP=tcp://10.0.0.11:6379
REDIS_PRIMARY_PORT_6379_TCP_PROTO=tcp
REDIS_PRIMARY_PORT_6379_TCP_PORT=6379
REDIS_PRIMARY_PORT_6379_TCP_ADDR=10.0.0.11

BinaryData
====

Events:  <none>

$ kubectl apply -f cmfile-volume-pod.yaml

$ kubectl exec cmfile-volume-pod -- ls -l /opt/redis/config

$ kubectl exec cmfile-volume-pod -- cat /opt/redis/config/redis.conf