Kustomize Basic

kubernetes manifest 리소스 관리 도구

Kustomize

• https://kubernetes.io/ko/docs/tasks/manage-kubernetes-objects/kustomization/
• kubernetes manifest (yaml) 파일을 Template 형태로 관리 Patch(Merge) 및 배포 해주는 툴
• kubernetes 1.14 이후, kubectl 명령어로 kustomization 지원

---

Simple Example

$ tree .
.
├── deployment.yaml
├── kustomization.yaml
└── version.yaml

kustomization.yaml

• Manifest 파일의 기본 구조 및 리소스, 패치 파일을 기술하는 파일

resources:
- deployment.yaml
patchesStrategicMerge:
- version.yaml

• resources : 리소스 파일 리스트
  • resources 이외에 configMapGenerator, secretGenerator 기능도 있음
  • https://kubernetes.io/ko/docs/tasks/manage-kubernetes-objects/kustomization/#kustomize-%EA%B8%B0%EB%8A%A5-%EB%A6%AC%EC%8A%A4%ED%8A%B8
• patchesStrategicMerge : resources의 Patch 파일

Patch : yaml file merge

resources:

• deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mvcapp
spec:
  selector:
    matchLabels:
      app: mvcapp
  replicas: 2
  template:
    metadata:
      labels:
        app: mvcapp
    spec:
      containers:
      - name: mvcapp
        image: cdecl/mvcapp:0.4
        imagePullPolicy: Always
        ports:
        - containerPort: 80

---
apiVersion: v1
kind: Service
metadata:
  name: mvcapp
spec:
  type: NodePort
  #type: LoadBalancer
  #loadBalancerIP: 192.168.0.10
  selector:
    app: mvcapp
  ports:
  - port: 80
    targetPort: 80
    nodePort: 30010

patchesStrategicMerge:

• version.yaml
  • spec.replicas 와 spec.template.spec.containers.image 를 변경

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mvcapp
spec:
  replicas: 4
  template:
    spec:
      containers:
      - name: mvcapp
        image: cdecl/mvcapp:0.5

실행 테스트

$ kubectl kustomize “kustomization_directory”

• 리소스파일 deployment.yaml 이 version.yaml 값으로 patch (merge) 됨
  • spec.replicas
  • spec.template.spec.containers.image

$ kubectl kustomize .
apiVersion: v1
kind: Service
metadata:
  name: mvcapp
spec:
  ports:
  - nodePort: 30010
    port: 80
    targetPort: 80
  selector:
    app: mvcapp
  type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mvcapp
spec:
  replicas: 4
  selector:
    matchLabels:
      app: mvcapp
  template:
    metadata:
      labels:
        app: mvcapp
    spec:
      containers:
      - image: cdecl/mvcapp:0.5
        imagePullPolicy: Always
        name: mvcapp
        ports:
        - containerPort: 80

---

Base와 Overlay

• Kustomize 를 관리하기 위해 디렉토리 구조 권고
• base : 기본이 되는 Kustomize 환경
• overlays : Patch 되는 환경으로 구분
  • e.g. dev, stage, prod

$ tree
.
├── base
│   ├── deployment.yaml
│   ├── kustomization.yaml
│   └── version.yaml
└── overlays
    ├── dev
    │   ├── kustomization.yaml
    │   └── version.yaml
    └── prod
        ├── kustomization.yaml
        └── version.yaml

overlays/dev/kustomization.yaml

• namePrefix: name 앞에 prefix
• bases : kustomization 기본(base) 환경 경로
• patchesStrategicMerge : base 적용 후, 추가 Patch

namePrefix: dev-
bases:
- ../../base
patchesStrategicMerge:
- version.yaml

---

설치 테스트

manifest 파일의 kubectl -f 옵션 대신 kubectl -k 옵션 사용

$ kubectl apply -k “kustomization_directory”

Install (apply)

$ kubectl apply -k overlays/dev

get/describe

$ kubectl get -k overlays/dev
$ kubectl describe -k overlays/dev

diff

• 클러스터 상태와 manifest 파일 비교

$ kubectl diff -k overlays/dev
...
   creationTimestamp: "2021-12-15T08:08:11Z"
-  generation: 1
+  generation: 2
   managedFields:
   - apiVersion: apps/v1
     fieldsType: FieldsV1
@@ -93,7 +93,7 @@
   uid: 4610c9b8-501d-4b27-8a77-ab4fbf3c73e8
 spec:
   progressDeadlineSeconds: 600
-  replicas: 2
+  replicas: 4
   revisionHistoryLimit: 10
   selector:
     matchLabels:

delete

kubectl delete -k overlays/dev