k8s-reloader

👨‍💻簡介

• 🔗github-repo : stakater/Reloader: A Kubernetes controller to watch changes in ConfigMap and Secrets and do rolling upgrades on Pods with their associated Deployment, StatefulSet, DaemonSet and DeploymentConfig – [✩Star] if you’re using it! (github.com)

🔰基礎介紹

運作原理

1. Reloader偵測所有資源變化，對有變化的資源使用SHA1計算資源的哈西值
2. Reloader查看是否有設定相關的annotation，並查看有設定annotation資源的特殊環境變量
3. 對有設定annotation的資源比對其哈希值，如果環境變量中哈希值不同，則更新環境變量，如果環境變量不存在，則創建一個

環境變量名稱

• ConfigMap：STAKATER_{configmap_name}_CONFIGMAP ，比如 ConfigMap 的名稱為 foo，則生成的環境變量的名稱為：STAKATER_FOO_CONFIGMAP。
• Secret：STAKATER_{secret_name}_SECRET ，比如 Secret 的名稱為 foo，則生成的環境變量的名稱為：STAKATER_FOO_SECRET。

環境變量的值

版本需求

k8s版本需 = 1.9

安裝方式

1. 使用Manifests安裝

kubectl apply -f https://raw.githubusercontent.com/stakater/Reloader/master/deployments/kubernetes/reloader.yaml

1. 使用Kustomize安裝

kubectl apply -k https://github.com/stakater/Reloader/deployments/kubernetes

apiVersion: kustomize.config.k8s.io/v1beta1

kind: Kustomization



bases:

  - https://github.com/stakater/Reloader/deployments/kubernetes



namespace: reloader

1. 使用Helm安裝

helm repo add stakater https://stakater.github.io/stakater-charts



helm repo update



helm install stakater/reloader # For helm3 add --generate-name flag or set the release name

預設情況下，reloader會偵測所有namespace的資源，如果要針對單一namespace可使用--set reloader.watchGlobally為false，以下範例為安裝在test namespace並只偵測test namespace底下的資源

helm install stakater/reloader --set reloader.watchGlobally=false --namespace test # For helm3 add --generate-name flag or set the release name

使用方式

1. 自動偵測所有資源

設定reloader.stakater.com/auto: "true"

kind: Deployment

metadata:

  annotations:

    reloader.stakater.com/auto: "true"

spec:

  template:

    metadata:

1. 限制只偵測有設定annotations的資源

deploy設定reloader.stakater.com/search: "true"，configmap等資源設定reloader.stakater.com/match: "true"

kind: Deployment

metadata:

  annotations:

    reloader.stakater.com/search: "true"

spec:

  template:

---

kind: ConfigMap

metadata:

  annotations:

    reloader.stakater.com/match: "true"

data:

  key: value

reloader.stakater.com/auto與reloader.stakater.com/search不能同時使用如果使用reloader.stakater.com/auto，則reloader.stakater.com/match不管有沒有設定都會被偵測

1. 只偵測特定資源

資源使用,做分隔

• Configmap

kind: Deployment

metadata:

  annotations:

    configmap.reloader.stakater.com/reload: "foo-configmap"

spec:

  template:

    metadata:

• Secret

kind: Deployment

metadata:

  annotations:

    secret.reloader.stakater.com/reload: "foo-secret,bar-secret,baz-secret"

spec:

  template: 

    metadata:

🎯setup

1. 部署reloader

kubectl apply -f https://raw.githubusercontent.com/stakater/Reloader/master/deployments/kubernetes/reloader.yaml

apiVersion: v1

kind: ConfigMap

metadata:

  name: nginx-map

  annotations:

	reloader.stakater.com/match: "true"

data:

  test.conf: |

	server {

	  listen       80;

	  server_name  abc.com;



	  location / {

		  root  /usr/share/nginx/html ;

		  index index.html index.htm;

	  }

	}

---

apiVersion: apps/v1

kind: Deployment

metadata:

  name: nginx

  annotations:

	configmap.reloader.stakater.com/reload: "nginx-map"

spec:

  replicas: 2

  selector:

	matchLabels:

	  service: http-server

  template:

	metadata:

	  labels:

		service: http-server

	spec:

	  containers:

	  - name: nginx

		image: sz9751210/nginx-reloader:v1

		imagePullPolicy: IfNotPresent

		ports:

		- containerPort: 80

		volumeMounts:

		- mountPath: /etc/nginx/conf.d # mount nginx-conf volumn to /etc/nginx/conf.d

		  readOnly: true

		  name: deployment-nginx-conf

	  volumes:

		- name: deployment-nginx-conf

		  configMap:

			name: nginx-map # place ConfigMap `nginx-conf` on /etc/nginx

---

apiVersion: v1

kind: Service

metadata:

  name: nginx-service

spec:

  selector:

	service: http-server

  ports:

  - port: 80

	targetPort: 80

部署

kubectl apply -f k8s-reloader-demo.yaml

1. 打開瀏覽器查看nginx

minikube service nginx-service --url

Reference