Скачать или смотреть 4. customizing helm charts kubernetes

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Customizing Helm charts enables you to reuse pre-built charts and customize them to meet your specific requirements. Helm charts are templated using the Go programming language, which allows you to customize charts by modifying their values, templates, or adding new templates.

Here are some of the key subtopics covered in Topic 4:

1. Explore and modify Chart properties:

Charts can be customized by modifying their properties. You can modify chart properties via multiple ways, but the easiest one is using the `--set` flag while installing a chart. You can pass in argument in exactly the same way as you pass environment variables in the terminal. For example:


$ helm install stable/mariadb --set rootUser.password=secret,replication.password=my-password


The above command installs and sets the root password for your MariaDB instance to 'secret', and the replication password to 'my-password'.

2. Learn how to use variables using `{{ .Values }}`:

You can customize Helm charts by using variables inside templates. The variables in Helm are stored in the `values.yaml` file, located inside the root directory of the chart. You can reference these variables inside the chart by using Go template syntax.

Example YAML file `values.yaml`:


replicaCount: 1
image:
repository: nginx
tag: stable
containerPort: 80


Example Kubernetes manifest to use `Values`:

```
apiVersion: apps/v1
kind: Deployment
metadata:
name: myapp
spec:
replicas: {{ .Values.replicaCount }}
selector:
matchLabels:
app: myapp
template:
metadata:
labels:
app: myapp
spec:
containers:
name: myapp
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
ports:
containerPort: {{ .Values.containerPort }}


3. Using Helm Conditional statements `{{ if my-condition }} do-something {{end}}`:

You can use conditional statements in Helm charts to make Helm more flexible with conditions inside Kubernetes manifest templates. Helm executes these if/else statements or loops and sends the resulting configuration into the manifest Kubernetes. For example, you can add a conditional statement inside the Kubernetes manifest file to conditionally expose your container port depending on the chart value.


apiVersion: v1
kind: Service
metadata:
name: myapp-svc
labels:
app: myapp
spec:
type: NodePort
ports:
{{- if .Values.exposePort }}
port: 80
protocol: TCP
targetPort: 8080
{{- end }}
selector:
app: myapp

4. Working with multiple value files:

If you are working on a complex deployment, you may need to have multiple configurations for each environment. Instead of having separate chart directories for each environment, Helm provides a better way to manage the changes in each environment by using multiple values files.

You can use these files to store the configuration for each environment, such as `prod.yaml`, `dev.yaml`, etc. By using multiple values files, you can reuse a single chart across all environments and avoid the need for creating separate charts for each environment.

You can combine these files by using the `--values` flag when installing the chart.


$ helm install myrelease mychart --values values-prod.yaml --values values-secrets.yaml




In summary, there are multiple ways to customize a Helm chart, and all of them involve modifying the chart's `values.yaml`, chart's properties, using variables inside templates, including conditionals or loops within templates, etc.



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