Install helm (version >3.x) cli, Follow the steps described in this link.
Run the below command to ensure the version.
$ helm version --short
Go to the directory where you would like to create the chart. Run the below command, which creates chart with pre-defined templates. Use the name of the chart as your application/module name.
$ helm create <name>
$ helm create chartexample
This will create the folder with the name of the chart in current working directory. Change to the newly created directory (chartexample) and view the contents
$ cd chartexample
$ tree
.
├── Chart.yaml
├── charts
├── templates
│ ├── NOTES.txt
│ ├── _helpers.tpl
│ ├── deployment.yaml
│ ├── hpa.yaml
│ ├── ingress.yaml
│ ├── service.yaml
│ ├── serviceaccount.yaml
│ └── tests
│ └── test-connection.yaml
└── values.yaml
- Chart.yaml
- This defines the chart and its key properties.
- values.yaml
- Define all the configurable properties for the chart deployment.
- charts
- You may add any dependent chart(s) into this directory
- templates
- A directory of templates that, when combined with values, will generate valid Kubernetes manifest files. The templates are written using Go Template Language.
apiVersion: v2 - v2 represents helm3 compatible charts
name: chartexample - name of the chart
type: application - Default is application. Other supported value is Library
version: 0.1.0 - This is the chart version, increment this version if you change the app version or any change to the deployment templates.
appVersion: 1.16.0 - Your application version. Change whenver there is any change to the application.
Apart from the above there are many optional fields available.
The default configuration values for this chart. This comes with pre-defined set of properties which are used in the templates. You may add or modify them, remember to change the templates which depends on these default properties.
In my example, i would like to change the below in values.yaml
image:
repository: harivemula/kubeconfigexample
...
serviceAccount:
create: false
...
resources:
limits:
cpu: 500m
memory: 750Mi
requests:
cpu: 500m
memory: 750Mi
...
autoscaling:
enabled: true
minReplicas: 1
maxReplicas: 2
targetCPUUtilizationPercentage: 80I'm introducing few more properties in values.yaml
port:
containerPort: 8080
volumeMounts:
- name: cache-volume
mountPath: /cache
volumes:
- name: cache-volume
emptyDir: {}
env:
- name: DEMO_ENV_PROP
value: mydemoenvproperty
- name: ENV_PROP
value: justenvpropIn the above content, i have used the same structure of kubernetes manifest for adding new properties, however it is not manadatory. It all depends on how you want to use the property in templates.
Example, we have defined port.containerPort in the above example, and going to use this in the templates/deployments.yaml as
ports:
- name: http
containerPort: {{ .Values.port.containerPort }}Instead you may define simply as container_port: 8080 in values.yaml and refer it in templates/deployment.yaml like below
ports:
- name: http
containerPort: {{ .Values.container_port }}By default templates directory contains templates for below kubernetes objects.
- deployment
- service
- service account
- ingress
- horizontal pod autoscaling
You may add any other objects you need, like configmap.
The _helpers.tpl file defines named templates.
Example, it defines a templete to derive name of the chart. Go to the link.
{{- define "chartexample.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}Modify the provided templates to suite to your requirement. In my case i have modified the deployment.yaml with highlighted fields below.
...
ports:
- name: http
containerPort: {{ .Values.port.containerPort }}
protocol: TCP
...
env:
{{- toYaml .Values.env | nindent 12 }}
...
volumeMounts:
- name: config-volume
mountPath: /workspace/config
{{- toYaml .Values.volumeMounts | nindent 12 }}
...
volumes:
- name: config-volume
configMap:
name: {{ .Release.Name }}-samplespringconfig
{{- toYaml .Values.volumes | nindent 8 }}
...
In the above lets take couple of examples
env:
{{- toYaml .Values.env | nindent 12 }}env: As in my values.yaml, i have defined the same structure it should be in kubernetes manifest, now i am trying to simply get the env property values and copying here as yaml output with indent 12.
volumes:
- name: config-volume
configMap:
name: {{ .Release.Name }}-samplespringconfig
{{- toYaml .Values.volumes | nindent 8 }}volumes: I have defined a volume with configmap as source here in the template directly and if any other volumes defined on values.yaml, all will be added here as yaml with indent 8. And the name of the configmap is based on the chart release name.
I would like to create configmap to pass some properties to my application and use the configmap as volume to deployment. For that, i am adding a new file in templates directory as configmap.yaml.
apiVersion: v1
kind: ConfigMap
metadata:
name: {{ .Release.Name }}-samplespringconfig
data:
application.properties: |
demo.file.prop=ValueFromConfigIn the configmap, i am using the name as Release.Name prefix, which is the name we give when we deploy the chart. So, the configmap object name is dynamic. You can use templates in the data section as well.
Once you have completed with your modifications, you can package the chart. Before packaging, verify if the chart is well formed by running
helm lintRun the below to package chart
helm package .This will package your chart with name < chartname >-< chartversion >.tgz. Example, chartexample-0.1.0.tgz
You may run the below command to install the application to kubernetes cluster. Assuming kubernetes context is set to right cluster
helm install <chart release name> <chart location/chart directory>
helm install testapp chartexample-0.1.0.tgz
or
helm install testapp chartexample/You can upload the helm chart to chart repository like chart museum and refer the repo to install chart to your kubernetes cluster.