Install software on kubernetes cluster using helm 3 package manager

Introduce

Helm yes Kubernetes Package manager , It allows developers and network administrators to work more easily in Kubernetes Configure and deploy applications on the cluster .

Helm The bag is called charts, They contain resource definition templates , These templates can deploy and configure a given application , Users only need to pay the least work .

Use templates , You can manage charts by passing in variable definitions 、 Its settings and behavior , Without modifying the actual chart .Helm Automatically manage custom resource definitions and modifications to deployed definitions . Deployed with possible customization chart be called Release .

In this tutorial , You will set Helm 3 And learn how to install 、 upgrade 、 Rollback and manage charts and versions . You will also learn to create and package your own charts , And setting up the chart repository , Which hosts charts that you can install immediately .

The first 0 Step - establish k8s Environmental Science

This tutorial uses CSDN Development cloud provides k8s learning environment , One click creates k8s Environmental Science .CSDN Developing the cloud k8s The learning environment is paid by the hour , Only per hour 0.1 element . After learning, you can release the host resources and the billing will stop .

Click here to have k8s Environmental Science .
You can also use other methods to create your own k8s colony .

Click on 【 Buy now 】 after , In a few minutes you can have your own k8s colony .

• Installed on the local computer kubectl Command line tools , Configured to connect to your cluster .kubectl You can find it in the official documents Read more about installation in .

You can also use ssh Terminal tool login k8s Cluster host , Perform the following operations in the server terminal

You can use the following command to test your connectivity ：

kubectl cluster-info

If you don't receive any errors , Then you are connected to the cluster . If you use to access multiple clusters kubectl, Please make sure to verify that you have selected the correct cluster context by running the following command ：

kubectl config get-contexts

The above command lists the available configurations ：

CURRENT   NAME      CLUSTER   AUTHINFO   NAMESPACE
*         default   default   default

ad locum , asterisk ( *) Indicates that we are connected to default colony . To switch clusters , Please run ：

kubectl config use-context <context-name>

When you connect to the correct cluster , Continue with step 1 Start installation Helm.

The first 1 Step — install Helm 3

In this section , You will use the official shell Script install Helm 3 .

First switch to /tmp, You will run the following command to store the installation script ：

cd /tmp

Use the following command to download the script ：

curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3

You can use a text editor to view get_helm.sh Content to ensure its security .

Set its permission to be executable through the following command ：

chmod +x get_helm.sh

Last , Run it to install Helm 3：

./get_helm.sh

You will receive output similar to the following ：

Downloading https://get.helm.sh/helm-v3.9.0-linux-amd64.tar.gz
Verifying checksum... Done.
Preparing to install helm into /usr/local/bin
helm installed into /usr/local/bin/helm

Your machine is equipped with Helm 3. Now you will understand charts Repositories and how to use them

The first 2 Step — Set up chart repository

Helm charts Stored in charts Repository , Anyone can trust . By default ,Helm 3 No repository is preconfigured . The previous version of Helm Including a central charts The repository ; However ,Helm 3 The design of evolves into charts Developers manage their own repositories , Thus allowing more freedom and faster release . This means for everyone you want to use chart, You need to make sure that the managed repository is added to your Helm Installing .

To help you find the right repository , You can use ArtifactHub.io , This is a result of CNCF Managed open source website , Yes Helm charts And its repository . It also tracks other CNCF Popular and useful charts used in the project , So it's different from stable The previous version of Helm The repository used . For common projects , for example Nginx ingresses or monitoring Tools , It's a good choice .

You can search the homepage to install chart. Search for nginx All... Related to it will be displayed chart.

Search for ingress-nginx To find it in your results . Select by Kubernetes Community version of team management , Click to access its page .

Every chart There is a detailed description of its functions , And add its repository to your installation and installation diagram . without , You can still press... On the right side of the page INSTALL Button to get the necessary commands .

Every chart There is a detailed description of its functions , And add its repository to your installation and installation diagram .

without , You can still press... On the right side of the page INSTALL Button to get the necessary commands .

You can copy it by clicking the blue button next to the command . Do this for the first command , Then run it ：

helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx

To add a repository to Helm, Please run helm repo add. The parameters it accepts are the name of the repository and its location .

The output will be ：

WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: /root/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: /root/.kube/config
"ingress-nginx" has been added to your repositories

The warning is because k8s The configuration file of is not secure , Users in the same user group and other users can read this file

Solve this alarm , Modify the permissions ：

chmod g-rw ~/.kube/config
chmod o-r ~/.kube/config

function helm version The alarm information is gone

When you add a new repo when , You need to make Helm Know what it contains ：

helm repo update

You will receive the following output , Indicates that the update was successful ：

Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "ingress-nginx" chart repository
Update Complete. ⎈Happy Helming!⎈

In this step , You've got it ArtifactHub And what it provides . You also want to Helm Installation adds a new repository . In the next step , You will install Helm chart.

The first 3 Step — install Helm Chart

In the last section , You have ingress-nginx chart Added repository . You now install it into your cluster .

Every chart There are configuration variables , You can set these variables to modify their behavior . These variables are stored in a file named , This document values.yaml Is part of the chart . Unless you have downloaded the chart to your computer , Otherwise, you must run the following command to view it ：

helm show values <chart_name>

To display the Available variables for ingress-nginx, Please replace chart_name：

helm show values ingress-nginx/ingress-nginx

Will output ingress-nginx Of values.yaml Content , It's a lot of stuff

To install chart, You can use helm install command , The format is as follows ：

helm install <release_name> <repository/chart_name>

release_name yes chart Deployment instance *,* I'll call it here ingress-nginx.

This command will use the default value of the variable to install the chart into your cluster . If you want to modify some of them , You can use the following methods to pass in new variable values --set：

helm install ingress-nginx/ingress-nginx --set variable_name=variable_value

You can repeat any as needed --set Quantity variable . Because we won't customize it now , So install it as is by running ：

helm install ingress-nginx ingress-nginx/ingress-nginx

The output will be similar to the following ：

NAME: ingress-nginx
LAST DEPLOYED: Sat Jul  9 16:02:19 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None
NOTES:
The ingress-nginx controller has been installed.
It may take a few minutes for the LoadBalancer IP to be available.
You can watch the status by running 'kubectl --namespace default get services -o wide -w ingress-nginx-controller'

An example Ingress that makes use of the controller:
  apiVersion: networking.k8s.io/v1
  kind: Ingress
  metadata:
    name: example
    namespace: foo
  spec:
    ingressClassName: nginx
    rules:
      - host: www.example.com
        http:
          paths:
            - pathType: Prefix
              backend:
                service:
                  name: exampleService
                  port:
                    number: 80
              path: /
    # This section is only required if TLS is to be enabled for the Ingress
    tls:
      - hosts:
        - www.example.com
        secretName: example-tls

If TLS is enabled for the Ingress, a Secret containing the certificate and key must also be provided:

  apiVersion: v1
  kind: Secret
  metadata:
    name: example-tls
    namespace: foo
  data:
    tls.crt: <base64 encoded cert>
    tls.key: <base64 encoded key>
  type: kubernetes.io/tls

Please note that ,NAME Corresponding to the version name you specified .Helm It also lists common information , For example, publish the state and the namespace to deploy it . The NOTES Partial cause chart But different , It usually contains a quick start guide or a warning about some common pitfalls when using chart resources . ad locum , It indicates that a load balancer is being created , And it may take some time to complete .

To check deployed chart, Please use helm list：

helm list

You'll find that ingress-nginx It is the only one deployed at present chart：

NAME         	NAMESPACE	REVISION	UPDATED                                	STATUS      	CHART              	APP VERSION
ingress-nginx	default  	1       	2022-07-09 07:25:32.861880478 +0800 CST	deployed    	ingress-nginx-4.1.4	1.2.1

You can find its services in the cluster by running the following command ：

kubectl get services

The output will be similar ：

NAME                                 TYPE           CLUSTER-IP      EXTERNAL-IP    PORT(S)                      AGE
ingress-nginx-controller             LoadBalancer   10.245.211.81   116.196.125.86 80:30704/TCP,443:30700/TCP   7m19s
ingress-nginx-controller-admission   ClusterIP      10.245.50.17    <none>         443/TCP                      7m19s
kubernetes                           ClusterIP      10.245.0.1      <none>         443/TCP                      83m

Now you have deployed the release to the cluster , You will modify its configuration at deployment .

The first 4 Step — Upgraded version

After deployment and release , You don't need to dismantle it and completely redeploy it when you need to change its configuration . You can use this helm upgrade The command uses the new version chart Upgrade release , Or set new settings .

The ingress-nginx chart It's public controller.replicaCount Control deployed controller pod Quantity variable . By default , It's set to 1, You can list the available pod Check it out. ：

kubectl get pods

You will find that there is only one ：

NAME                                        READY   STATUS    RESTARTS   AGE
ingress-nginx-controller-7fc74cf778-kjtst   1/1     Running   0          12m

If you want to deploy more instances to achieve high availability （ for example , Three ）, You can run upgrade Release and set the variable to 3：

helm upgrade ingress-nginx ingress-nginx/ingress-nginx --set controller.replicaCount=3 --reuse-values

You also introduced --reuse-values, It indicates Helm Base your changes on the deployed version , Keep the previous configuration .

In the output ,Helm The version will be modified to indicate that the version has been upgraded ：

NAME: ingress-nginx
LAST DEPLOYED: Sat Jul  9 16:02:19 2022
NAMESPACE: default
STATUS: deployed
REVISION: 2
TEST SUITE: None
NOTES:
...

You can list available by running pod：

kubectl get pods

You will find three listed pod, Instead of a ：

NAME                                        READY   STATUS    RESTARTS   AGE
ingress-nginx-controller-7c54d79885-6sb8z   1/1     Running   0          21h
ingress-nginx-controller-7c54d79885-qrwf6   1/1     Running   0          27h
ingress-nginx-controller-7c54d79885-fzrc8   1/1     Running   0          21h

Next , You will rollback the changes and completely delete the version .

The first 5 Step — Rollback and delete version

When you upgrade When it was released , Its revision number will be increased . In the internal ,Helm Store all revisions of the version , Allows you to return to previous revisions when needed .

To put pod The number of is restored to only one , You can helm upgrade Run again and set the quantity manually , Because this is a small change . however , When using chart when , Manual restore is not elegant .

To rollback the version , Please use helm rollback：

helm rollback <release_name> <release_revision>

You can use it ingress-nginx Restore your changes by rolling back to the revision 1：

helm rollback ingress-nginx 1

You will receive the following output , Indicates successful operation ：

Rollback was a success! Happy Helming!

You can check the current version by listing the published version ：

helm list

You will find that the revised version is 3, instead of 1：

NAME         	NAMESPACE	REVISION	UPDATED                               	STATUS  	CHART              	APP VERSION
ingress-nginx	default  	3       	2022-07-10 21:53:57.94583986 +0800 CST	deployed	ingress-nginx-4.1.4	1.2.1

Helm Change each （ Including rollback ） As a new revision to the release . You can check the deployment by running the following command pod To check the revision 3 Is it equal to the first ：

kubectl get pods

You will find that there is only one ：

NAME                                        READY   STATUS    RESTARTS   AGE
ingress-nginx-controller-7c54d79885-6sb8z   1/1     Running   0          22h

To delete a version and all its revisions , You can use helm delete：

helm delete <release_name>

Because you no longer need it , please ingress-nginx Delete by running the following command ：

helm delete ingress-nginx

The output will be ：

release "ingress-nginx" uninstalled

You can list the versions to check if there are no ：

helm list

The output table will have no rows ：

NAMESPACE       REVISION        UPDATED STATUS  CHART   APP VERSION

Now this version has been deleted , You can reuse its name in future deployments .

The first 6 Step - Create custom charts

In this optional step , You will learn how to create customizations chart、 Where to place the resource definition and how to package it for further distribution .

You will create one called The new chart example-chart. Run the following command to create it ：

helm create example-chart

This will create a file named example-chart New directories for the following files and structures ：

example-chart/
├── charts
├── Chart.yaml
├── templates
│   ├── deployment.yaml
│   ├── _helpers.tpl
│   ├── hpa.yaml
│   ├── ingress.yaml
│   ├── NOTES.txt
│   ├── serviceaccount.yaml
│   ├── service.yaml
│   └── tests
│       └── test-connection.yaml
└── values.yaml

The resources you will install on the target cluster , The definition is located in this templates Directory .

Helm The default deployment created is a Nginx Entrance controller . Although their file extensions are YAML, But they use Go The template syntax of is customizable through the public variables you can pass in . You can run the following command to display service.yaml Content ：

cat example-chart/templates/service.yaml

You will find that it supports template instructions , Enclosed in double brackets are template syntax

apiVersion: v1
kind: Service
metadata:
  name: {
    {
     include "example-chart.fullname" . }}
  labels:
    {
    {
    - include "example-chart.labels" . | nindent 4 }}
spec:
  type: {
    {
     .Values.service.type }}
  ports:
    - port: {
    {
     .Values.service.port }}
      targetPort: http
      protocol: TCP
      name: http
  selector:
    {
    {
    - include "example-chart.selectorLabels" . | nindent 4 }}

The value of the referenced variable is in the file values.yaml In the definition of .

After deployment Helm According to the NOTES The text is stored in in NOTES.txt, And it is also templated .

chart Metadata , For example, the name of the deployed software 、 Version and version , In the file Chart.yaml It is specified in ：

apiVersion: v2
name: mychart
description: A Helm chart for Kubernetes

...
type: application

...
version: 0.1.0

...
appVersion: "1.16.0"

To check Helm What will be deployed , You can pass in --dry-run and --debug Point to helm install chart Catalog ：

helm install example-chart --dry-run --debug ./example-chart

The output will be very long , And include all the final resource definitions that will be applied to your cluster . After modifying the chart , You can use helm upgrade Push the new version to Kubernetes.

When you need to share what you have done chart when , You can package it for distribution by running the following ：

helm package ./example-chart

The output will be ：

Successfully packaged chart and saved it to: .../example-chart-0.1.0.tgz

You can install packaged charts as you add them to the repository ：

helm install example-chart example-chart-0.1.0.tgz

In this step , You created and deployed a custom chart . You also packed it , And understand its structure .

Conclusion

You know how to use it now Helm Install and upgrade the deployment software to Kubernetes colony .

You have added chart The repository , And learned how to use ArtifactHub Find them .

You also created a new customization chart And learned about the version revision and how to rollback when necessary .

More about creating custom charts , Please visit Official Guide .