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This article will explain in detail how to use helm in docker. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

In K8s, for stateless applications such as nginx and myapp, we can use the deployment controller to scale very easily.

For stateful applications such as tomcat, redis, and etcd single-instance applications, we use deployment to limit it to only one instance, which is no problem.

However, for multiple instances of stateful applications, such as redis master and slave, it is not so easy.

Helm is another project of K8s, the equivalent of linux's yum.

We know that in the yum repository, yum not only solves the dependencies between packages, but also provides specific packages. However, there are only configuration manifest files in the helm repository, but there are no images, which are still provided by the image repository, such as hub.docker.com, private repository and so on.

In other words, helm provides all the manifest files needed for an application. For example, for a nginx, we need a manifest file for deployment, a manifest file for service, and a manifest file for hpa. We package these three files together, which is an application package, which we call Chart.

Generally speaking, Chart is a helm package, its essence is just a template, we can assign to this template (value), and form our custom manifest file, also achieve our production personalized needs. Such a repository is called a Chart repository (which is actually a https/http server).

Helm packages Kubernetes resources (such as deployments, services, ingress, etc.) into a chart, while chart is stored in an chart repository. The chart repository can be used to store and share chart.

Helm works outside the K8s cluster. Helm does not directly manipulate apiserver, but rather interacts with Tiller. Tlller then interacts with apiserver, and finally Apiserver assigns the chart using config (value file), and finally deploys it as release.

In helm work, helm first checks whether the chart exists, and then downloads the chart to the home directory of the current helm user. Then helm gives the chart to tiller,tiller and then interacts with api server. Once api server deploys chart on a K8s cluster, it is no longer called chart, but release.

Therefore, a chart assignment is different, it is possible to deploy multiple release, so we can think of chart as a template to install the package.

If chart is found to be updated, helm automatically scrolls the update, and helm supports one-click rollback.

Install the helm server

Helm is installed on a server outside of the K8s cluster.

You can download the installation package for helm at the following link:

Https://github.com/helm/helm/releases

After downloading it, it is a helm command that you can use directly:

[root@master linux-amd64] # mv helm / usr/bin/ [root@master linux-amd64] # helm-hThe Kubernetes package managerTo begin working with Helm Run the 'helm init' command:$ helm initThis will install Tiller to your running Kubernetes cluster.It will also set up any necessary local configuration.Common actions from this point include:- helm search: search for charts- helm fetch: download a chart to your local directory to view- helm install: upload the chart to Kubernetes- helm list: list releases of chartsEnvironment: $HELM_HOME set an alternative location for Helm files. By default, these are stored in ~ / .helm $HELM_HOST set an alternative Tiller host The format is host:port $HELM_NO_PLUGINS disable plugins. Set HELM_NO_PLUGINS=1 to disable plugins. $TILLER_NAMESPACE set an alternative Tiller namespace (default "kube-system") $KUBECONFIG set an alternative Kubernetes configuration file (default "~ / .kube / config")

We saw that the helm was deployed, and it was so simple and rough.

Configure rbac

Sample rbac configuration file: https://github.com/helm/helm/blob/master/docs/rbac.md

[root@master helm] # cat tiller-rbac.yaml apiVersion: v1kind: ServiceAccountmetadata: name: tiller namespace: kube-system---apiVersion: rbac.authorization.k8s.io/v1kind: ClusterRoleBindingmetadata: name: tillerroleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: cluster-adminsubjects:-kind: ServiceAccount name: tiller namespace: kube-system [root@master helm] # kubectl apply-f tiller-rbac.yaml serviceaccount/tiller createdclusterrolebinding.rbac.authorization.k8s.io/tiller created [root@master Helm] # kubectl get sa-n kube-system | grep tillertiller 1 21m deployment Tiller [root@master helm] # export NO_PROXY='172.16.0.0/16127.0.0.0/0' # you can add this if you have done linux proxy It is not possible to add this environment variable [root@master helm] # helm init-- service-account tillerCreating / root/.helm Creating / root/.helm/repository Creating / root/.helm/repository/cache Creating / root/.helm/repository/local Creating / root/.helm/plugins Creating / root/.helm/starters Creating / root/.helm/cache/archive Creating / root/.helm/repository/repositories.yaml Adding stable repo with URL: https://kubernetes-charts.storage.googleapis.com Adding local Repo with URL: http://127.0.0.1:8879/charts $HELM_HOME has been configured at / root/.helm.Tiller (the Helm server-side component) has been installed into your Kubernetes Cluster.Please note: by default Tiller is deployed with an insecure 'allow unauthenticated users' policy.For more information on securing your installation see: https://docs.helm.sh/using_helm/#securing-your-helm-installationHappy Helming!

Since Helm pulls the image from storage.googleapis.com by default, you can use the following command to install it if the machine you are running cannot access the domain name:

[root@master helm] # helm init-upgrade-tiller-image registry.cn-hangzhou.aliyuncs.com/google_containers/tiller:v2.9.1-stable-repo-url https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts

See that tiller's pod is up and running:

[root@master helm] # kubectl get pods-n kube-system-o wide | grep tillertiller-deploy-759cb9df9-t6b2l 1 Running 0 18m 10.244.2.89 node2

See that helm works and connects to the K8s cluster.

[root@master ~] # helm version

Client: & version.Version {SemVer: "v2.9.1", GitCommit: "20adb27c7c5868466912eebdf6664e7390ebe710", GitTreeState: "clean"}

Server: & version.Version {SemVer: "v2.9.1", GitCommit: "20adb27c7c5868466912eebdf6664e7390ebe710", GitTreeState: "clean"}

Use helm

1. Change the helm warehouse source

The helm source address used by helm by default is https://kubernetes-charts.storage.googleapis.com, but because Chinese mainland is indescribable, it needs to be replaced with Ali's helm source. The change method is as follows:

[root@master ~] # helm repo remove stable "stable" has been removed from your repositories [root@master ~] # helm repo add stable https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts"stable" has been added to your repositories

2. View locally available helm sources

[root@master ~] # helm repo listNAME URL local http://127.0.0.1:8879/charts stable https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts

3. Update helm warehouse

[root@master] # helm repo updateHang tight while we grab the latest from your chart repositories.Skip local chart repository...Successfully got an update from the "stable" chart repositoryUpdate Complete. ⎈ Happy Helming! ⎈

3. Search in the warehouse

[root@master ~] # helm search # list all available applications in the helm repository [root@master ~] # helm search mysql # filter operation NAME CHART VERSIONAPP VERSIONDESCRIPTION stable/mysql 0.3.5 Fast, reliable, scalable And easy to use open-...stable/percona 0.3.0 free, fully compatible, enhanced, open source d...stable/percona-xtradb-cluster0.0.2 5.7.19 free, fully compatible, enhanced Open source d...stable/gcloud-sqlproxy 0.2.3 Google Cloud SQL Proxy stable/mariadb 2.1.6 10.1.31 Fast, reliable, scalable, and easy to use open-...

4. View application details

[root@master ~] # helm inspect stable/mysql

Note: the above stable is the name of the warehouse, which is shown through helm repo list

5. Helm source

Https://hub.kubeapps.com/

6. Install the software package with helm

[root@master] # helm install-- name mysql1 stable/mysql

-- name: specify the release name

7. View the installed software packages

[root@master ~] # helm listNAME REVISIONUPDATED STATUS CHART NAMESPACEmysql11 Wed Oct 17 04:50:58 2018DEPLOYEDmysql-0.3.5default

8. Uninstall the installed package

[root@master ~] # helm delete mysql1release "mysql1" deleted

9. Summary

Helm Common commands release Management: install delete upgrade/rollback list history View release Historical version status get release status Information chart Management: create # create a chart to generate the underlying chart sample file For us to modify and download a char from the repository to the local get inspect package verify with fetch

10. Helm downloads the installation package to the current user's home directory by default

When we install or fetch, we will download the installation package to the current user's home directory:

[root@master archive] # ll / root/.helm/cache/archive/total 8murr RWMurray Rafael-1 root root 5536 Oct 17 04:50 mysql-0.3.5.tgz

11. Modify the values.yaml in chart to realize personalized installation

[root@master archive] # cd / root/.helm/cache/archive [root@master archive] # lsmysql-0.3.5.tgz [root@master archive] # tar-xvf mysql-0.3.5.tgz [root@master archive] # tree mysqlmysql ├── Chart.yaml # description of chart's ├── README.md ├── templates # template file │ ├── configmap.yaml │ ├── deployment.yaml │ ├── _ helpers.tpl │ ├ ── NOTES.txt │ ├── pvc.yaml │ ├── secrets.yaml │ └── svc.yaml └── values.yaml # modify the corresponding parameters of this file yourself You can customize the contents of the installation package

If we have personalized installation requirements, we can change the contents of the values.yaml file, which can be placed in any location, after the change:

[root@master mysql] # helm install-- name mysql1-f / root/values.yaml stable/mysql

Note:-- name specifies a custom release name.

12. View the prompts after deployment

After deploying the application package with helm, there will be a lot of tips, which are very important, but if you don't record it in time, is there any way to check it again? The answer is yes. Find them in the following ways:

[root@master] # helm status mysql1LAST DEPLOYED: Wed Oct 17 04:50:58 2018NAMESPACE: defaultSTATUS: DEPLOYEDRESOURCES:== > v1/ServiceNAME TYPE CLUSTER-IP EXTERNAL-IP PORT (S) AGEmysql1-mysql ClusterIP 10.110.40.169 3306/TCP 15hrs = > v1beta1/DeploymentNAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGEmysql1-mysql 11 1015hrs = > v1/Pod (related) NAME READY STATUS RESTARTS AGEmysql1-mysql-7b7f7ffcd5-vrs9d 0 Pending 0 15 hrs = > v1/SecretNAME TYPE DATA AGEmysql1-mysql Opaque 2 15 hrs = > v1/PersistentVolumeClaimNAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGEmysql1-mysql Pending 15hNOTES:MySQL can be accessed via port 3306 on the following DNS name from within your cluster:mysql1-mysql.default.svc.cluster.localTo get your root password run: MYSQL_ROOT_PASSWORD=$ (kubectl get secret-- namespace default mysql1-mysql) -o jsonpath= "{.data.MySQL-root-password}" | base64-- decode Echo) To connect to your database:1. Run an Ubuntu pod that you can use as a client: kubectl run-I-- tty ubuntu-- image=ubuntu:16.04-- restart=Never-- bash-il2. Install the mysql client: $apt-get update & & apt-get install mysql-client-y3. Connect using the mysql cli Then provide your password: $mysql-h mysql1-mysql-pTo connect to your database directly from outside the K8s cluster: MYSQL_HOST=127.0.0.1 MYSQL_PORT=3306 # Execute the following commands to route the connection: export POD_NAME=$ (kubectl get pods-- namespace default-l "app=mysql1-mysql"-o jsonpath= "{.items [0] .metadata.name}") kubectl port-forward $POD_NAME 3306 mysql1-mysql 3306 mysql-h ${MYSQL_HOST}-P ${MYSQL _ PORT}-u root-p$ {MYSQL_ROOT_PASSWORD} create an available custom chart

1. Download a chart from the repository to the local

[root@master helm] # helm fetch stable/mysql [root@master helm] # lsmysql-0.3.5.tgz [root@master helm] #

2. View the directory structure of chart

[root@master helm] # tree mysqlmysql ├── Chart.yaml # initializes the entire chart to indicate its metadata information and record the current chart version, name, maintainer, internal maintenance information and other ├── README.md # this is a text file in markdown format, and this is a README file that explains how this chart is developed.-requirements.yaml: whether the current chart depends on other chart This file is optional. ├── templates # all template files that can be reused It is good to be familiar with the go language │ ├── configmap.yaml │ ├── deployment.yaml │ ├── _ helpers.tpl │ ├── NOTES.txt # the final display information provided to the user │ ├── pvc.yaml │ ├── secrets.yaml │ └── svc.yaml └── values.yaml # mainly sets the default value for the custom attributes in the template template |-charts / # other chart that the current chart depends on This is optional 1 directory, 10 files

You can check the official chart manual to understand the meaning of each project:

Https://docs.helm.sh/developing_charts/#charts

3. Generate basic chart sample files with helm

[root@master helm] # helm create myappCreating myapp

Note: myapp is the name of chart

[root@master helm] # tree myapp/myapp/ ├── charts ├── Chart.yaml ├── templates │ ├── deployment.yaml │ ├── _ helpers.tpl │ ├── ingress.yaml │ ├── NOTES.txt │ └── service.yaml └── values.yaml

4. Do grammar check

[root@master helm] # lsmyapp [root@master helm] # helm lint myapp== > Linting myapp [INFO] Chart.yaml: icon is recommended1 chart (s) linted, no failures

5. Packing

[root@master helm] # lsmyapp [root@master helm] # helm package myapp/Successfully packaged chart and saved it to: / root/helm/myapp-0.1.0.tgz [root@master helm] # lsmyapp myapp-0.1.0.tgz

Saw that myapp was packaged into myapp-0.1.0.tgz.

6. Start the service of 8879 warehouse

[root@master helm] # helm repo listNAME URL local http://127.0.0.1:8879/charts stable https://kubernetes.oss-cn-hangzhou.aliyuncs.com/charts[root@master helm] # helm serveRegenerating index. This may take a moment.Now serving you on 127.0.0.1:8879

7. Check whether there is a chart package we created in the local warehouse.

[root@master ~] # helm search myappNAME CHART VERSIONAPP VERSIONDESCRIPTION local/myapp0.1.0 1.0 A Helm chart for Kubernetes

8. Deploy our custom chart

[root@master] # helm install-- name myapp1 local/myapp

9. Delete our deployed chart

[root@master] # helm delete-- purge myapp1release "myapp1" deleted on "how to use helm in docker" ends here. I hope the above content can be helpful to you, so that you can learn more knowledge. If you think the article is good, please share it for more people to see.

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