前言
相信经过前一篇文章的学习，大家已经对Helm有所了解，本篇文章介绍另一款工具 Kustomize，为什么Helm如此流行，还会出现 Kustomize？而且 Kustomize 自 kubectl 1.14以来早已内置到其中，说明官方对其很认可。
我认为还是Helm 参数化模板方式来自定义配置需要学习复杂的DSL语法，难上手，易出错，而 kustomize 是使用 Kubernetes 原生概念帮助用户创作并复用声明式配置。
认识 Kustomize
安装
brew install kustomize示例解析
demo-manifests
├── base
│ ├── deployment.yaml
│ ├── kustomization.yaml
│ ├── service-account.yaml
│ └── service.yaml
└── services
├── demo-app
│ ├── _common
│ │ ├── deployment-patch.yaml
│ │ ├── kustomization.yaml
│ │ └── namespace.yaml
│ ├── dev
│ │ ├── config.json
│ │ ├── deployment-patch.yaml
│ │ └── kustomization.yaml
│ ├── staging
│ │ ├── config.json
│ │ ├── deployment-patch.yaml
│ │ └── kustomization.yaml
│ └── prod
│ │ ├── config.json
│ │ ├── deployment-patch.yaml
│ │ └── kustomization.yaml
└── demo-app2
└── xxx
先看base 目录，有几个常见的deployment/service/service-account YAML 资源文件
还有个 kustomization.yaml 配置文件
这里面包含了刚才的几个resource文件以及要应用于它们的一些自定义，如添加一个通用的标签Common Labels
这时候也可以通过 kustomize build 命令来生成完整的YAML进行查看
kustomize build demo-manifests/base > base.yaml
base.yamlbuild 出来的 YAML 每个资源对象上都会存在通用的标签 managed-by: Kustomize
接下来看 Service目录，此目录存放所有的服务项目，比如demo-app ， 里面的YAML就是来覆盖base 也就是官方说的 Overlays
只需要把不同的资源描述通过Patch方式覆盖掉base中的就行了。这边我又将三个环境 dev/staging/prod 公共的部分抽取出来放入 common文件夹。
_common/kustomization.yaml文件如下
apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization resources: - ../../../base - namespace.yaml patchesStrategicMerge: - deployment-patch.yaml
我这个demo-app 需要configMap，另外心跳接口也不一样， 所以 deployment-patch.yaml 需要写出这些不一样的，然后去覆盖base中的。
apiVersion: apps/v1
kind: Deployment
metadata:
name: NAME_PLACEHOLDER
spec:
template:
spec:
serviceAccountName: NAME_PLACEHOLDER
containers:
- name: app
image: wadexu007/demo:IMG_TAG_PLACEHOLDER
livenessProbe:
failureThreshold: 5
httpGet:
path: /pizzas
port: 8080
initialDelaySeconds: 10
periodSeconds: 40
timeoutSeconds: 1
readinessProbe:
failureThreshold: 5
httpGet:
path: /pizzas
port: 8080
initialDelaySeconds: 10
periodSeconds: 20
timeoutSeconds: 1
volumeMounts:
- name: config-volume
mountPath: /app/conf/config.json
subPath: config.json
volumes:
- name: config-volume
configMap:
name: demo-app-config
--- apiVersion: v1 kind: Namespace metadata: name: demo
### 文章首发于博客园 https://www.cnblogs.com/wade-xu/p/16839829.html
最后我们看 dev/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1 kind: Kustomization resources: - ../_common
namespace: demo
commonLabels: app: demo-app
replicas: - count: 1 name: demo-app configMapGenerator: - files: - config.json name: demo-app-config patches: - patch: |- - op: replace path: /metadata/name value: demo-app target: name: NAME_PLACEHOLDER
patchesStrategicMerge: - deployment-patch.yaml
images: - name: wadexu007/demo newTag: 1.0.0
dev env 里面将replicas设置成1， 用config.json 生成 configMap
{
"SOME_CONFIG": "/demo/path"
}
deployment-patch.yaml 里面也将container resource request/limit 配置设置小一点， 采用 patchesStrategicMerge 与 common 和 base里面的deployment资源合并。
apiVersion: apps/v1
kind: Deployment
metadata:
name: NAME_PLACEHOLDER
spec:
template:
spec:
containers:
- name: app
resources:
limits:
cpu: 1
memory: 1Gi
requests:
cpu: 200m
memory: 256Mi
另外还采用了 patch 的方式，改了每个资源的name --> demo-app
以及images 替换了原来的 image name and tag.
kustomize 命令如下
kustomize build demo-manifests/services/demo-app/dev > demo-app.yaml
如果用 kubectl 命令的话，示例如下
kubectl kustomize services/demo-app/dev/ > demo-app.yaml
最终结果
apiVersion: v1
kind: Namespace
metadata:
labels:
app: demo-app
name: demo
---
apiVersion: v1
kind: ServiceAccount
metadata:
labels:
app: demo-app
managed-by: Kustomize
name: demo-app
namespace: demo
---
apiVersion: v1
data:
config.json: |-
{
"SOME_CONFIG": "/demo/path"
}
kind: ConfigMap
metadata:
labels:
app: demo-app
name: demo-app-config-t7c64mbtt2
namespace: demo
---
apiVersion: v1
kind: Service
metadata:
labels:
app: demo-app
managed-by: Kustomize
name: demo-app
namespace: demo
spec:
ports:
- port: 8080
protocol: TCP
targetPort: http
selector:
app: demo-app
managed-by: Kustomize
type: ClusterIP
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: demo-app
managed-by: Kustomize
name: demo-app
namespace: demo
spec:
replicas: 1
selector:
matchLabels:
app: demo-app
managed-by: Kustomize
template:
metadata:
labels:
app: demo-app
managed-by: Kustomize
spec:
containers:
- image: wadexu007/demo:1.0.0
imagePullPolicy: IfNotPresent
livenessProbe:
failureThreshold: 5
httpGet:
path: /pizzas
port: 8080
initialDelaySeconds: 10
periodSeconds: 40
timeoutSeconds: 1
name: app
ports:
- containerPort: 8080
name: http
readinessProbe:
failureThreshold: 5
httpGet:
path: /pizzas
port: 8080
initialDelaySeconds: 10
periodSeconds: 20
timeoutSeconds: 1
resources:
limits:
cpu: 1
memory: 1Gi
requests:
cpu: 200m
memory: 256Mi
securityContext:
allowPrivilegeEscalation: false
volumeMounts:
- mountPath: /app/conf/config.json
name: config-volume
subPath: config.json
serviceAccountName: demo-app
volumes:
- configMap:
name: demo-app-config-t7c64mbtt2
name: config-volume
### https://www.cnblogs.com/wade-xu/p/16839829.html
staging/prod 文件夹也是类似dev的文件，环境不一样，config.json 以及资源配置，image tag 不一样，显示申明就行了。
完整代码请参考我的 Github
涵盖 Kustomize 知识点
- commonLabels
- patchesStrategicMerge
- patches
- configMapGenerator
- replicas
- images
总结
经过本篇文章的学习，以及上一篇 [云原生之旅 - 5）Kubernetes时代的包管理工具 Helm ]关于Helm的学习，您已经能体会到两款工具的不同之处。