helm schema gen plugin

So that you don't have to write values.schema.json by hand from scratch for your Helm 3 charts

Helm plugin to generate JSON Schema for values yaml

Note about the project

This is a fork of karuppiah7890's project. Their work laid the foundation for what this project is today and what it will become. We appreciate their contributions and commitment to the project.

Install

The plugin works with both Helm v2 and v3 versions as it's agnostic to the Helm binary version

$ helm plugin install https://github.com/rhoat/helm-schema-gen
Downloading https://github.com/rhoat/helm-schema-gen/releases/download/0.0.8/helm-schema-gen-linux-amd64.tgz
Preparing to install into /home/user/.local/share/helm/plugins/helm-schema-gen
Installed plugin: schema-gen

Offline install

To install this offline:

• clone the repository
• copy it to the desired host
• cd to that directory
• run helm plugin install .

But note that the schema feature is present only in Helm v3 charts, so Helm chart still has to be v3, meaning - based on the Helm chart v3 spec. And the schema validation is only done in Helm v3. Read more in the Schema Files section of the Helm official docs.

Usage

The plugin works with both Helm v2 and v3 versions

Let's take a sample values.yaml like the below

autoscaling:
  enabled: false
  minReplicas: 1 
  maxReplicas: 100
  targetCPUUtilizationPercentage: 80
  # targetMemoryUtilizationPercentage: 80

Now if you use the plugin and pass the values.yaml to it, you will get the JSON Schema for the values.yaml

{
    "$schema": "http://json-schema.org/schema#",
    "type": "object",
    "properties": {
        "autoscaling": {
            "type": "object",
            "properties": {
                "enabled": {
                    "type": "boolean"
                },
                "maxReplicas": {
                    "type": "integer"
                },
                "minReplicas": {
                    "type": "integer"
                },
                "targetCPUUtilizationPercentage": {
                    "type": "integer"
                }
            }
        }
    }
}

You can save it to a file like this

helm schema-gen generate ./values.yaml --destination json.schema

schemagen helpers

Warning

This is an experimental feature.

For more advanced use cases, if you want to modify the type that is output you can leverage the schemagen comments.

Tip

The tool looks at the Headcomment on the yaml node, in order to make sure your comment isn't picked up as a footer its best to leave a space above your comment shown below.

autoscaling:
  enabled: false
  minReplicas: 1 

  # +schemagen:type:number
  maxReplicas: 100
  targetCPUUtilizationPercentage: 80
  # targetMemoryUtilizationPercentage: 80

When run with the -schemagen flag, you will be able to specify the type that is output in your json.

Note

There is no restriction on the type that can be put in here, so if you mistype something or put in garbage you will get garbage out.

helm schema-gen generate ./testdata/values.yaml --schemagen --destination json.schema

{
    "$schema": "http://json-schema.org/schema#",
    "type": "object",
    "properties": {
        "autoscaling": {
            "type": "object",
            "properties": {
                "enabled": {
                    "type": "boolean"
                },
                "maxReplicas": {
                    "type": "number"
                },
                "minReplicas": {
                    "type": "integer"
                },
                "targetCPUUtilizationPercentage": {
                    "type": "integer"
                }
            }
        }
    }
}

Issues? Feature Requests? Proposals? Feedback?

Put them all in GitHub issues 😁