[英]Kubernetes Rolling Update with Helm2
我正在嘗試使用Helm v2執行Kubernetes 滾動更新; 但是,我不能。
當我對慢速 Tomcat 鏡像執行helm upgrade
時,原始 pod 被破壞。
我想弄清楚如何通過使用新的 Pods 實例逐步更新並排空舊的 Pods 實例來實現零停機時間。
為了演示,我創建了一個示例慢速 Tomcat Docker 鏡像和一個Helm 圖表。
helm install https://github.com/h-q/slowtom/raw/master/docs/slowtom.tgz --name slowtom \
-f https://github.com/h-q/slowtom/raw/master/docs/slowtom/environments/initial.yaml
您可以通過運行kubectl logs -f slowtom-sf-0
來跟蹤日志,一旦准備就緒,您就可以訪問http://localhost:30901
上的應用程序
helm upgrade slowtom https://github.com/h-q/slowtom/raw/master/docs/slowtom.tgz \
-f https://github.com/h-q/slowtom/raw/master/docs/slowtom/environments/upgrade.yaml
upgrade.yaml
與initial.yaml
部署文件相同,但標記版本號除外。
在這里,原始 pod 被破壞,新的 pod 開始。 同時,用戶無法訪問http://localhost:30901
上的應用程序
helm del slowtom --purge
curl -LO https://github.com/h-q/slowtom/raw/master/docs/slowtom.tgz
tar vxfz ./slowtom.tgz
helm install --debug ./slowtom --name slowtom -f ./slowtom/environments/initial.yaml
helm upgrade --debug slowtom ./slowtom -f ./slowtom/environments/upgrade.yaml
Dockerfile
FROM tomcat:8.5-jdk8-corretto
RUN mkdir /usr/local/tomcat/webapps/ROOT && \
echo '<html><head><title>Slow Tomcat</title></head><body><h1>Slow Tomcat Now Ready</h1></body></html>' >> /usr/local/tomcat/webapps/ROOT/index.html
RUN echo '#!/usr/bin/env bash' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo 'x=2' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo 'secs=$(($x * 60))' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo 'while [ $secs -gt 0 ]; do' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo ' >&2 echo -e "Blast off in $secs\033[0K\r"' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo ' sleep 1' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo ' : $((secs--))' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo 'done' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo '>&2 echo "slow cataline done. will now start real catalina"' >> /usr/local/tomcat/bin/slowcatalina.sh && \
echo 'exec catalina.sh run' >> /usr/local/tomcat/bin/slowcatalina.sh && \
chmod +x /usr/local/tomcat/bin/slowcatalina.sh
ENTRYPOINT ["/usr/local/tomcat/bin/slowcatalina.sh"]
slowtom/Chart.yaml
apiVersion: v1
description: slow-tomcat Helm chart for Kubernetes
name: slowtom
version: 1.1.2 # whatever
slowtom/values.yaml
# Do not use this file, but ones from environmments folder
slowtom/environments/initial.yaml
# Storefront
slowtom_sf:
name: "slowtom-sf"
hasHealthcheck: "true"
isResilient: "false"
replicaCount: 2
aspect_values:
- name: y_aspect
value: "storefront"
image:
repository: hqasem/slow-tomcat
pullPolicy: IfNotPresent
tag: 1
env:
- name: y_env
value: whatever
slowtom/environments/upgrade.yaml
# Storefront
slowtom_sf:
name: "slowtom-sf"
hasHealthcheck: "true"
isResilient: "false"
replicaCount: 2
aspect_values:
- name: y_aspect
value: "storefront"
image:
repository: hqasem/slow-tomcat
pullPolicy: IfNotPresent
tag: 2
env:
- name: y_env
value: whatever
slowtom/templates/deployment.yaml
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: {{ .Values.slowtom_sf.name }}
labels:
chart: "{{ .Chart.Name | trunc 63 }}"
chartVersion: "{{ .Chart.Version | trunc 63 }}"
visualize: "true"
app: {{ .Values.slowtom_sf.name }}
spec:
replicas: {{ .Values.slowtom_sf.replicaCount }}
selector:
matchLabels:
app: {{ .Values.slowtom_sf.name }}
template:
metadata:
labels:
app: {{ .Values.slowtom_sf.name }}
visualize: "true"
spec:
dnsPolicy: ClusterFirstWithHostNet
containers:
- name: {{ .Values.slowtom_sf.name }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
imagePullPolicy: {{ .Values.image.pullPolicy }}
command: ["/usr/local/tomcat/bin/slowcatalina.sh"]
args: ["whatever"]
env:
{{ toYaml .Values.env | indent 12 }}
{{ toYaml .Values.slowtom_sf.aspect_values | indent 12 }}
resources:
{{ toYaml .Values.resources | indent 12 }}
---
slowtom/templates/service.yaml
kind: Service
apiVersion: v1
metadata:
name: {{.Values.slowtom_sf.name}}
labels:
chart: "{{ .Chart.Name | trunc 63 }}"
chartVersion: "{{ .Chart.Version | trunc 63 }}"
app: {{.Values.slowtom_sf.name}}
visualize: "true"
hasHealthcheck: "{{ .Values.slowtom_sf.hasHealthcheck }}"
isResilient: "{{ .Values.slowtom_sf.isResilient }}"
spec:
type: NodePort
selector:
app: {{.Values.slowtom_sf.name}}
sessionAffinity: ClientIP
ports:
- protocol: TCP
port: 8080
targetPort: 8080
name: http
nodePort: 30901
---
與Deployment
不同, StatefulSet
在滾動更新期間不會在銷毀舊 Pod 之前啟動新 Pod。 相反,期望的是您有多個 Pod,並且它們將被一個一個地替換。 由於您只配置了 1 個副本,因此必須先銷毀它。 將副本數量增加到 2 個或更多,或者切換到Deployment
模板。
https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#rolling-update
我通過向我的deployment.yaml
添加就緒或啟動探測器解決了這個問題
slowtom/templates/deployment.yaml
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: {{ .Values.slowtom_sf.name }}
labels:
chart: "{{ .Chart.Name | trunc 63 }}"
chartVersion: "{{ .Chart.Version | trunc 63 }}"
visualize: "true"
app: {{ .Values.slowtom_sf.name }}
spec:
replicas: {{ .Values.slowtom_sf.replicaCount }}
selector:
matchLabels:
app: {{ .Values.slowtom_sf.name }}
template:
metadata:
labels:
app: {{ .Values.slowtom_sf.name }}
visualize: "true"
spec:
dnsPolicy: ClusterFirstWithHostNet
containers:
- name: {{ .Values.slowtom_sf.name }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
imagePullPolicy: {{ .Values.image.pullPolicy }}
command: ["/usr/local/tomcat/bin/slowcatalina.sh"]
args: ["whatever"]
env:
{{ toYaml .Values.env | indent 12 }}
{{ toYaml .Values.slowtom_sf.aspect_values | indent 12 }}
resources:
{{ toYaml .Values.resources | indent 12 }}
readinessProbe:
httpGet:
path: /
port: 8080
initialDelaySeconds: 60
periodSeconds: 30
timeoutSeconds: 1
failureThreshold: 3
---
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