最簡單的 K8S 部署檔案編寫姿勢，沒有之一！
阿新 • • 發佈：2020-12-14
## 1. 頭疼編寫K8S部署檔案？
* `K8S yaml` 引數很多，需要邊寫邊查？
* 保留回滾版本數怎麼設？
* 如何探測啟動成功，如何探活？
* 如何分配和限制資源？
* 如何設定時區？否則列印日誌是GMT標準時間
* 如何暴露服務供其它服務呼叫？
* 如何根據CPU和記憶體使用率來配置水平伸縮？
首先，你需要知道有這些知識點，其次要把這些知識點都搞明白也不容易，再次，每次編寫依然容易出錯！
## 2. 建立服務映象
[前一篇文章](https://juejin.cn/post/6904508173328547854) 講解了如何快速建立自己的服務映象，不過為了演示，這篇文章我們以 `redis:6-alpine` 映象為例。
## 3. 完整K8S部署檔案編寫過程
* 首先安裝 `goctl` 工具
`GO111MODULE=on GOPROXY=https://goproxy.cn/,direct go get -u github.com/tal-tech/go-zero/tools/goctl`
* 一鍵生成K8S部署檔案
`goctl kube deploy -name redis -namespace adhoc -image redis:6-alpine -o redis.yaml -port 6379`
生成的 `yaml` 檔案如下：
```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: redis
namespace: adhoc
labels:
app: redis
spec:
replicas: 3
revisionHistoryLimit: 5
selector:
matchLabels:
app: redis
template:
metadata:
labels:
app: redis
spec:
containers:
- name: redis
image: redis:6-alpine
lifecycle:
preStop:
exec:
command: ["sh","-c","sleep 5"]
ports:
- containerPort: 6379
readinessProbe:
tcpSocket:
port: 6379
initialDelaySeconds: 5
periodSeconds: 10
livenessProbe:
tcpSocket:
port: 6379
initialDelaySeconds: 15
periodSeconds: 20
resources:
requests:
cpu: 500m
memory: 512Mi
limits:
cpu: 1000m
memory: 1024Mi
volumeMounts:
- name: timezone
mountPath: /etc/localtime
volumes:
- name: timezone
hostPath:
path: /usr/share/zoneinfo/Asia/Shanghai
---
apiVersion: v1
kind: Service
metadata:
name: redis-svc
namespace: adhoc
spec:
ports:
- port: 6379
selector:
app: redis
---
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: redis-hpa-c
namespace: adhoc
labels:
app: redis-hpa-c
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: redis
minReplicas: 3
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
targetAverageUtilization: 80
---
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: redis-hpa-m
namespace: adhoc
labels:
app: redis-hpa-m
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: redis
minReplicas: 3
maxReplicas: 10
metrics:
- type: Resource
resource:
name: memory
targetAverageUtilization: 80
```
* 部署服務，如果 `adhoc` namespace不存在的話，請先通過 `kubectl create namespace adhoc` 建立
````shell
$ kubectl apply -f redis.yaml
deployment.apps/redis created
service/redis-svc created
horizontalpodautoscaler.autoscaling/redis-hpa-c created
horizontalpodautoscaler.autoscaling/redis-hpa-m created
````
* 檢視服務允許狀態
```
$ kubectl get all -n adhoc
NAME READY STATUS RESTARTS AGE
pod/redis-585bc66876-5ph26 1/1 Running 0 6m5s
pod/redis-585bc66876-bfqxz 1/1 Running 0 6m5s
pod/redis-585bc66876-vvfc9 1/1 Running 0 6m5s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/redis-svc ClusterIP 172.24.15.8 6379/TCP 6m5s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/redis 3/3 3 3 6m6s
NAME DESIRED CURRENT READY AGE
replicaset.apps/redis-585bc66876 3 3 3 6m6s
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/redis-hpa-c Deployment/redis 0%/80% 3 10 3 6m6s
horizontalpodautoscaler.autoscaling/redis-hpa-m Deployment/redis 0%/80% 3 10 3 6m6s
```
* 測試服務
```shell
$ kubectl run -i --tty --rm cli --image=redis:6-alpine -n adhoc -- sh
/data # redis-cli -h redis-svc
redis-svc:6379> set go-zero great
OK
redis-svc:6379> get go-zero
"great"
```
## 4. 總結
`goctl` 工具極大簡化了 K8S yaml 檔案的編寫，提供了開箱即用的最佳實踐，並且支援了模板自定義。
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