kubernetes实战篇之helm使用技巧

系列目录

使用压缩包安装chart

我们使用helm package打包的时候,默认会在当前位置生成一个tgz压缩包,然后helm把它复制到到$HOME/.helm/repository目录下,现在还没有讲解helm私服搭建,使用的是helm自带的一个本地服务器,有时候这个服务器不能正常工作,但是我们又想体验功能,这时候可以使用本地chart压缩包来安装

我在当前目录下有以下文件

[centos@k8s-master helm]$ ls
get_helm.sh  mychart  mychart-0.1.0.tgz  mychart-0.2.0.tgz

[centos@k8s-master helm]$ helm install --name tylertest mychart-0.1.0.tgz
NAME:   tylertest
LAST DEPLOYED: Thu Apr 25 09:37:32 2019
NAMESPACE: default
STATUS: DEPLOYED

RESOURCES:
==> v1/Deployment
NAME               READY  UP-TO-DATE  AVAILABLE  AGE
tylertest-mychart  0/1    1           0          0s

==> v1/Pod(related)
NAME                                READY  STATUS             RESTARTS  AGE
tylertest-mychart-545479dd4b-wbdm4  0/1    ContainerCreating  0         0s

==> v1/Service
NAME               TYPE       CLUSTER-IP      EXTERNAL-IP  PORT(S)  AGE
tylertest-mychart  ClusterIP  10.107.107.190  <none>       80/TCP   0s

NOTES:
1. Get the application URL by running these commands:
  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=mychart,app.kubernetes.io/instance=tylertest" -o jsonpath="{.items[0].metadata.name}")
  echo "Visit http://127.0.0.1:8080 to use your application"
  kubectl port-forward $POD_NAME 8080:80

并且通过helm list可以看到它了

[centos@k8s-master helm]$ helm list
NAME                    REVISION        UPDATED                         STATUS          CHART                           APP VERSION     NAMESPACE
kubernetes-dashboard    1               Thu Mar 14 09:06:25 2019        DEPLOYED        kubernetes-dashboard-1.2.0      1.10.1          kube-system
tylertest               1               Thu Apr 25 09:37:32 2019        DEPLOYED        mychart-0.1.0                   1.0             default

当然也可以进入到$HOME/.helm/repository来安装它

安装的时候指定不同的环境

我们在安装一个chart的时候,由于环境不同,配置可能也会有差别,我们知道,chart的配置都存在values.yaml文件里,我们可以编写多个存储配置的yaml文件,在安装的时候通过-f指定 不同环境的values文件

[centos@k8s-master helm]$ helm install --name=tylertest -f mychart/values.yaml mychart
NAME:   tylertest
LAST DEPLOYED: Thu Apr 25 09:44:00 2019
NAMESPACE: default
STATUS: DEPLOYED

RESOURCES:
==> v1/Deployment
NAME               READY  UP-TO-DATE  AVAILABLE  AGE
tylertest-mychart  0/1    0           0          0s

==> v1/Pod(related)
NAME                                READY  STATUS   RESTARTS  AGE
tylertest-mychart-545479dd4b-m5wj5  0/1    Pending  0         0s

==> v1/Service
NAME               TYPE       CLUSTER-IP     EXTERNAL-IP  PORT(S)  AGE
tylertest-mychart  ClusterIP  10.108.206.51  <none>       80/TCP   0s

NOTES:
1. Get the application URL by running these commands:
  export POD_NAME=$(kubectl get pods --namespace default -l "app.kubernetes.io/name=mychart,app.kubernetes.io/instance=tylertest" -o jsonpath="{.items[0].metadata.name}")
  echo "Visit http://127.0.0.1:8080 to use your application"
  kubectl port-forward $POD_NAME 8080:80

注意,values.yaml是安装时缺省情况下使用的文件,我们可以可以把它复制若干(名字可以是任意名称,只需要在install的时候通过-f指定它的位置),根据不同环境进行修改.

这种方法同样也可以解决另外一个问题,那就是很多公共仓库的chart依赖gcr.io上的镜像导致国内无法安装成功,如果镜像地址做成了参数,则我们可以修改,如果没有做成参数,我们仍然有办法,那就是先通过helm fetch把它拉到本地,然后解压,然后修改其镜像文件重新打包,通过上面讲到过的使用本地压缩包安装的方式来安装.

让 Helm 连接到指定其它Kubernetes集群

Helm 默认使用和 kubectl 命令相同的配置访问 Kubernetes 集群，其配置默认在 ~/.kube/config 中。

部署时指定名称空间

我们前面的示例都默认是在的名称空间,实际生产环境中往往都不是按这种默认设置,而是安装在指定的名称空间中.如果想部署到指定的命令空间,执行helm install命令时 可以加上 --namespace 参数，比如：

helm install local/mychart --name tylertest --namespace mynamespace

查看某一部署应用的详细信息

其它跟kubectl get类似,helm也有get命令,可以通过它来查看部署应用详细信息

[centos@k8s-master helm]$ helm get tylertest
REVISION: 1
RELEASED: Thu Apr 25 09:44:00 2019
CHART: mychart-0.2.0
USER-SUPPLIED VALUES:
affinity: {}
fullnameOverride: ""
image:
  pullPolicy: IfNotPresent
  repository: nginx
  tag: stable
ingress:
  annotations: {}
  enabled: false
  hosts:
  - host: chart-example.local
    paths: []
  tls: []
nameOverride: ""
nodeSelector: {}
replicaCount: 1
resources: {}
service:
  port: 80
  type: ClusterIP
tolerations: []

COMPUTED VALUES:
affinity: {}
fullnameOverride: ""
image:
  pullPolicy: IfNotPresent
  repository: nginx
  tag: stable
ingress:
  annotations: {}
  enabled: false
  hosts:
  - host: chart-example.local
    paths: []
  tls: []
nameOverride: ""
nodeSelector: {}
replicaCount: 1
resources: {}
service:
  port: 80
  type: ClusterIP
tolerations: []

HOOKS:
---
# tylertest-mychart-test-connection
apiVersion: v1
kind: Pod
metadata:
  name: "tylertest-mychart-test-connection"
  labels:
    app.kubernetes.io/name: mychart
    helm.sh/chart: mychart-0.2.0
    app.kubernetes.io/instance: tylertest
    app.kubernetes.io/managed-by: Tiller
  annotations:
    "helm.sh/hook": test-success
spec:
  containers:
    - name: wget
      image: busybox
      command: ['wget']
      args:  ['tylertest-mychart:80']
  restartPolicy: Never
MANIFEST:

---
# Source: mychart/templates/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: tylertest-mychart
  labels:
    app.kubernetes.io/name: mychart
    helm.sh/chart: mychart-0.2.0
    app.kubernetes.io/instance: tylertest
    app.kubernetes.io/managed-by: Tiller
spec:
  type: ClusterIP
  ports:
    - port: 80
      targetPort: http
      protocol: TCP
      name: http
  selector:
    app.kubernetes.io/name: mychart
    app.kubernetes.io/instance: tylertest
---
# Source: mychart/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tylertest-mychart
  labels:
    app.kubernetes.io/name: mychart
    helm.sh/chart: mychart-0.2.0
    app.kubernetes.io/instance: tylertest
    app.kubernetes.io/managed-by: Tiller
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: mychart
      app.kubernetes.io/instance: tylertest
  template:
    metadata:
      labels:
        app.kubernetes.io/name: mychart
        app.kubernetes.io/instance: tylertest
    spec:
      containers:
        - name: mychart
          image: "nginx:stable"
          imagePullPolicy: IfNotPresent
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: http
          readinessProbe:
            httpGet:
              path: /
              port: http
          resources:
            {}

默认情况下会显示最新的版本的相关信息，如果想要查看指定发布版本的信息可加上 --revision 参数。

$ helm get  --revision 1  tylertest

chart中定义依赖

可以在要打包的chart目录中创建一个requirements.yaml文件定义该chart的依赖

$ cat > ./mychart/requirements.yaml <<EOF
dependencies:
- name: mariadb
  version: 0.6.0
  repository: https://kubernetes-charts.storage.googleapis.com
EOF

通过helm命令更新和下载cahrt的依赖

helm dep update ./mychart

在次安装运行chart时会把依赖中定义的chart运行起来