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

Code stuff

Nothing fancy about the code, all the heavy lifting is done by:

• go-jsonschema-generator - for generating JSON schema. It's a fork of this. Thanks to @mcuadros
• go-yaml - for YAML parsing
• cobra - for CLI stuff
• The Go stdlib - for everything else

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/KnechtionsCoding/helm-schema-gen.git
KnechtionsCoding/helm-schema-gen info checking GitHub for tag '0.0.4'
KnechtionsCoding/helm-schema-gen info found version: 0.0.4 for 0.0.4/Darwin/x86_64
KnechtionsCoding/helm-schema-gen info installed ./bin/helm-schema-gen
Installed plugin: schema-gen

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

replicaCount: 1

image:
  repository: nginx
  pullPolicy: IfNotPresent

imagePullSecrets: []
nameOverride: ""
fullnameOverride: ""

serviceAccount:
  # Specifies whether a service account should be created
  create: true
  # The name of the service account to use.
  # If not set and create is true, a name is generated using the fullname template
  name:

podSecurityContext: {}
  # fsGroup: 2000

securityContext: {}
  # capabilities:
  #   drop:
  #   - ALL
  # readOnlyRootFilesystem: true
  # runAsNonRoot: true
  # runAsUser: 1000

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  annotations: {}
    # kubernetes.io/ingress.class: nginx
    # kubernetes.io/tls-acme: "true"
  hosts:
    - host: chart-example.local
      paths: []
  tls: []
  #  - secretName: chart-example-tls
  #    hosts:
  #      - chart-example.local

resources: {}
  # We usually recommend not to specify default resources and to leave this as a conscious
  # choice for the user. This also increases chances charts run on environments with little
  # resources, such as Minikube. If you do want to specify resources, uncomment the following
  # lines, adjust them as necessary, and remove the curly braces after 'resources:'.
  # limits:
  #   cpu: 100m
  #   memory: 128Mi
  # requests:
  #   cpu: 100m
  #   memory: 128Mi

nodeSelector: {}

tolerations: []

affinity: {}

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

$ helm schema-gen values.yaml
{
    "$schema": "http://json-schema.org/schema#",
    "type": "object",
    "properties": {
        "affinity": {
            "type": "object"
        },
        "fullnameOverride": {
            "type": "string"
        },
        "image": {
            "type": "object",
            "properties": {
                "pullPolicy": {
                    "type": "string"
                },
                "repository": {
                    "type": "string"
                }
            }
        },
        "imagePullSecrets": {
            "type": "array"
        },
        "ingress": {
            "type": "object",
            "properties": {
                "annotations": {
                    "type": "object"
                },
                "enabled": {
                    "type": "boolean"
                },
                "hosts": {
                    "type": "array",
                    "items": {
                        "type": "object",
                        "properties": {
                            "host": {
                                "type": "string"
                            },
                            "paths": {
                                "type": "array"
                            }
                        }
                    }
                },
                "tls": {
                    "type": "array"
                }
            }
        },
        "nameOverride": {
            "type": "string"
        },
        "nodeSelector": {
            "type": "object"
        },
        "podSecurityContext": {
            "type": "object"
        },
        "replicaCount": {
            "type": "integer"
        },
        "resources": {
            "type": "object"
        },
        "securityContext": {
            "type": "object"
        },
        "service": {
            "type": "object",
            "properties": {
                "port": {
                    "type": "integer"
                },
                "type": {
                    "type": "string"
                }
            }
        },
        "serviceAccount": {
            "type": "object",
            "properties": {
                "create": {
                    "type": "boolean"
                },
                "name": {
                    "type": "null"
                }
            }
        },
        "tolerations": {
            "type": "array"
        }
    }
}

You can save it to a file like this

helm schema-gen values.yaml > values.schema.json

Issues? Feature Requests? Proposals? Feedback?

Put them all in GitHub issues