helm-schema

This tool tries to help you to easily create some nice JSON schema for your helm chart.

By default it will traverse the current directory and look for Chart.yaml files. For every file, helm-schema will try to find one of the given value filenames. The first files found will be read and a jsonschema will be created. For every dependency defined in the Chart.yaml file, a reference to the dependencies JSON schema will be created.

[!NOTE] The tool uses jsonschema Draft 7, because the library helm uses only supports that version.

Installation

Via go install:

go install github.com/dadav/helm-schema/cmd/helm-schema@latest

From aur:

paru -S helm-schema

Via podman/docker:

podman run --rm -v $PWD:/home/helm-schema ghcr.io/dadav/helm-schema:latest

Usage

Pre-commit hook

If you want to automatically generate a new values.schema.json if you change the values.yaml file, you can do the following:

Install pre-commit
Copy the .pre-commit-config.yaml to your helm chart repository.
Then run these commands:

pre-commit install
pre-commit install-hooks

Running the binary directly

You can also just run the binary yourself:

helm-schema

Options

The binary has the following options:

Flags:
  -r, --add-schema-reference          "add reference to schema in values.yaml if not found"
  -a, --append-newline                 append newline to generated jsonschema at the end of the file
  -c, --chart-search-root string      "directory to search recursively within for charts (default ".")"
  -x, --dont-strip-helm-docs-prefix   "disable the removal of the helm-docs prefix (--)"
  -d, --dry-run                       "don't actually create files just print to stdout passed"
  -h, --help                          "help for helm-schema"
  -s, --keep-full-comment             "keep the whole leading comment (default: cut at empty line)"
  -l, --log-level string              "level of logs that should printed, one of (panic, fatal, error, warning, info, debug, trace) (default "info")"
  -n, --no-dependencies               "don't analyze dependencies"
  -o, --output-file string            "jsonschema file path relative to each chart directory to which jsonschema will be written (default 'values.schema.json')"
  -f, --value-files strings           "filenames to check for chart values (default [values.yaml])"
  -k, --skip-auto-generation strings  "skip the auto generation for these fields (default [])"
  -u, --uncomment                     "consider yaml which is commented out"
  -v, --version                       "version for helm-schema"

Annotations

The jsonschema must be between two entries of # @schema :

# @schema
# my: annotation
# @schema
# you can add comment here as well
foo: bar

[!WARNING] It must be written just above the key you want to annotate.

[!NOTE] If you don't use the properties option on hashes/objects or don't use items on arrays, it will be parsed from the values and their annotations instead.

Available annotations

Key	Description	Values
`type`	Defines the jsonschema-type of the object. Multiple values are supported (e.g. `[string, integer]`) as a shortcut to `anyOf`	`object`, `array`, `string`, `number`, `integer`, `boolean` or `null`
`title`	Defines the title field of the object	Defaults to the key itself
`description`	Defines the description field of the object.	Defaults to the comments just above or below the `@schema` annotations block
`default`	Sets the default value and will be displayed first on the users IDE	Takes a `string`
`properties`	Contains a map with keys as property names and values as schema	Takes an `object`
`pattern`	Regex pattern to test the value	Takes an `string`
`format`	The format keyword allows for basic semantic identification of certain kinds of string values	Takes a keyword
`required`	Adds the key to the required items	`true` or `false` or `array`
`deprecated`	Marks the option as deprecated	`true` or `false`
`items`	Contains the schema that describes the possible array items	Takes an `object`
`enum`	Multiple allowed values. Accepts an array of `string`	Takes an `array`
`const`	Single allowed value	Takes a `string`
`examples`	Some examples you can provide for the end user	Takes an `array`
`minimum`	Minimum value. Can't be used with `exclusiveMinimum`	Takes an `integer`. Must be smaller than `maximum` or `exclusiveMaximum` (if used)
`exclusiveMinimum`	Exclusive minimum. Can't be used with `minimum`	Takes an `integer`. Must be smaller than `maximum` or `exclusiveMaximum` (if used)
`maximum`	Maximum value. Can't be used with `exclusiveMaximum`	Takes an `integer`. Must be bigger than `minimum` or `exclusiveMinimum` (if used)
`exclusiveMaximum`	Exclusive maximum value. Can't be used with `maximum`	Takes an `integer`. Must be bigger than `minimum` or `exclusiveMinimum` (if used)
`multipleOf`	The yaml-value must be a multiple of. For example: If you set this to 10, allowed values would be 0, 10, 20, 30...	Takes an `integer`
`additionalProperties`	Allow additional keys in maps. Useful if you want to use for example `additionalAnnotations`, which will be filled with keys that the `jsonschema` can't know	Defaults to `false` if the map is not an empty map. Takes a schema or boolean value
`patternProperties`	Contains a map which maps schemas to pattern. If properties match the patterns, the given schema is applied	Takes an `object`
`anyOf`	Accepts an array of schemas. None or one must apply	Takes an `array`
`oneOf`	Accepts an array of schemas. One or more must apply	Takes an `array`
`allOf`	Accepts an array of schemas. All must apply	Takes an `array`
`not`	A schema that must not be matched.	Takes an `object`
`if/then/else`	`if` the given schema applies, `then` also apply the given schema or `else` the other schema	Takes an `object`
`$ref`	Accepts an URI to a valid `jsonschema`. Extend the schema for the current key	Takes an URI (or relative file)
`minLength`	Minimum string length.	Takes an `integer`. Must be smaller or equal than `maxLength` (if used)
`maxLength`	Maximum string length.	Takes an `integer`. Must be greater or equal than `minLength` (if used)

Validation & completion

To take advantage of the generated values.schema.json, you can use it within your IDE through a plugin supporting the yaml-language-server annotation (e.g. VSCode - YAML)

You'll have to place this line at the top of your values.yaml ($schema=<path-or-url-to-your-schema>) :

# vim: set ft=yaml:
# yaml-language-server: $schema=values.schema.json

# @schema
# required: true
# @schema
# -- This is an example description
foo: bar

You can use the -r flag to make sure this line exists.

[!NOTE] You can also point to an online available schema, if you upload a version of yours and want other to be able to implement it.

yaml-language-server: $schema=https://example.org/my-json-schema.json

e.g. from github https://raw.githubusercontent.com/<user>/<repo>/main/values.schema.json

helm-docs

If you're using helm-docs, then you can combine both annotations and use both pre-commit hooks to automatically generate your documentation (e.g. README.md) alongside your values.schema.json.

If not provided, title will be the key and the description will be parsed from the helm-docs formatted comment.

# @schema
# type: array
# @schema
# -- helm-docs description here
foo: []

[!NOTE] Make sure to place the @schema annotations before the actual key description to avoid having it in your helm-docs generated table

Dependencies

Per default, helm-schema will try to also create the schemas for the dependencies in their respective chart directory. These schemas will be merged as properties in the main schema, but the requiredProperties field will be nullified, otherwise you would have to always overwrite all the required fields.

If you don't want to generate jsonschema for chart dependencies, you can use the -n, --no-dependencies option to only generate the values.schema.json for your parent chart(s)

Limitations

You can't change the jsonschema for dependencies by using @schema annotations on dependency config values. For example:

# foo is a dependency chart
foo:
  # You can't change the schema here, this has no effect.
  # @schema
  # type: number
  # @schema
  bar: 1

Examples

Some annotation examples you may want to use, to help you get started!

[!NOTE] See how the schema behaves with live examples : values.yaml

Below a snippet to test it out, with the current options helm-schema will not analyze dependencies (-n) and will omit the additionalProperties (-k, when not explicitly defined) in the generated schema. It will start looking for Chart.yaml and values.yaml files in examples/ (-c)

cd examples
helm-schema -n -k additionalProperties

# or

helm-schema -c examples -n -k additionalProperties

If you'd like to use helm-schema on your chart dependencies as well, you have to build and unpack them before. You'll avoid the "missing dependency" error message.

# go where your Chart.lock/yaml is located
cd <chart-name>

# build dependencies and untar them
helm dep build
ls charts/*.tgz |xargs -n1 tar -C charts/ -xzf

`type`

If type isn't specified, current value type will be used.

# Will be parsed as 'string'
# @schema
# title: Some title
# description: Some description
# @schema
name: foo

# Will be parsed as 'boolean'
# @schema
# type: boolean
# @schema
enabled: true

# You can define multiple types as an array.
# @schema
# type: [string, integer]
# minimum: 0
# @schema
cpu: 1

`title`

By default, the title will be parsed from the key name. If the key is foo, then title: foo.

# Define a custom title for the key
# @schema
# title: My custom title for 'foo'
# @schema
bar: foo

`description`

You can provide the description through its property or let it be parsed from your comments. If description is provided, the comments will not be parsed as description.

If you're implementing it alongside helm-docs, read this to do it correctly.

# This text will be used as description.
# @schema
# type: integer
# minimum: 1
# @schema
replica: 1

# @schema
# type: integer
# minimum: 1
# @schema
# This text will be used as description.
replica: 1

# @schema
# type: integer
# minimum: 1
# description: This text will be used as description.
# @schema
# And not this one
replica: 1

`default`

Help users when using their IDE to quickly retrieve the default value, for example through CTRL+SPACE.

# @schema
# default: standalone
# enum: [standalone,cluster]
# @schema
architecture: ""

# @schema
# type: boolean
# default: true
# @schema
enabled: true

`properties`

Allows user to define valid keys without defining them yet. Give the user an insight of the possible properties, their types and description.

By default, title for the keys defined under properties will inherit from the main key (e.g. here title: env). You need to provide title explicitly if you want to change it.

# @schema
# properties:
#   CONFIG_PATH:
#     title: CONFIG_PATH
#     type: string
#     description: The local path to the service configuration file
#   ADMIN_EMAIL:
#     title: ADMIN_EMAIL
#     type: string
#     format: idn-email
#   API_URL:
#     type: string
#     format: idn-hostname
#     description: Title will be 'env' as we do not specify it here
# @schema
# -- Environment variables. If you want to provide auto-completion to the user
env: {}

`pattern`

Pattern that'll be used to test the value.

# @schema
# pattern: ^api-key
# @schema
# The value have to start with the 'api-key-' prefix
apiKey: "api-key-xxxxx"

`format`

Known formats that the value must match. Formats available at JSON Schema - Formats.

# @schema
# format: idn-email
# @schema
# Requires a valid email format
email: foo@example.org

`required`

By default every property is a required property, you can disable this with required: false for a single key. You can also invert this behaviour with the option helm-schema -k required, now every property is an optional one.

# @schema
# required: false
# @schema
altName: foo

It's also possible to define an array of required properties on the parent.

# @schema
# required: [foo]
# @schema
altName:
  foo: bar

`deprecated`

Let the user know if the key is deprecated, hence should be avoided.

# @schema
# deprecated: true
# @schema
secret: foo

`items`

If you want to specify a schema for possible array values without using a default value. E.g. to define the structure of the hosts definition in an k8s ingress resource.

# @schema
# type: array
# items:
#   type: object
#   properties:
#     host:
#       type: object
#       properties:
#         url:
#           type: string
#           format: idn-hostname
# @schema
# Will give auto-completion for the below structure
# hosts:
#  - name:
#      url: my.example.org
hosts: []

`enum`

Allows user to define available values for a given key. Validation will fail and error shown if you try to put another value.

# @schema
# enum:
# - application
# - controller
# - api
# @schema
# Only those three values are accepted
type: application

# @schema
# type: array
# items:
#   enum: [api,frontend,backend,microservice,teamA,teamB,us-west-1,us-west-2]
# @schema
# For each array index, only one of those values are accepted
tags:
  - "api"
  - "teamA"
  - "us-west-2"

`const`

Defines a constant value which shouldn't be changed.

# @schema
# const: maintainer@example.org
# @schema
maintainer: maintainer@example.org

`examples`

Provides example values to the user when hovering the key in IDE, or by auto-completion mechanism.

# @schema
# format: ipv4
# examples: [192.168.0.1]
# @schema
clusterIP: ""

# @schema
# properties:
#   CONFIG_PATH:
#     type: string
#     description: The local path to the service configuration file
#     examples: [/path/to/config]
#   ADMIN_EMAIL:
#     type: string
#     format: idn-email
#     examples: [admin@example.org]
#   API_URL:
#     type: string
#     format: idn-hostname
#     examples: [https://api.example.org]
# @schema
# -- Provide auto-completion and examples to the user
env: {}

`minimum`

The value have to be above or equal the given integer.

# @schema
# minimum: 1
# @schema
replica: ""

`exclusiveMinimum`

The value have to be strictly above the given integer.

# @schema
# exclusiveMinimum: 0
# @schema
replica: ""

`maximum`

The value have to be below or equal the given integer.

# @schema
# maximum: 10
# @schema
replica: ""

`exclusiveMaximum`

The value have to be strictly below the given integer.

# @schema
# exclusiveMaximum: 5
# @schema
cpu: ""

`multipleOf`

The value have to be a multiple of the given integer.

# @schema
# multipleOf: 1024
# @schema
storageCapacity: 2048

`additionalProperties`

By default, additionalProperties is set to false unless you use the -k additionalProperties option. Useful when you don't know what nested keys you'll have.

# @schema
# additionalProperties: true
# @schema
# You'll be able to add as many keys below `env:` as you want without invalidating the schema
env:
  LONG: foo
  LIST: bar
  OF: baz
  VARIABLES: bat

# @schema
# additionalProperties: true
# properties:
#   REQUIRED_VAR:
#     type: string
# @schema
env:
  REQUIRED_VAR: foo
  OPTIONAL_VAR: bar

`patternProperties`

Mapping schemas to key name patterns. If properties match the patterns, the given schema is applied.

Useful when you work with a long list of keys and want to define a common schema for a group of them, for example.

E.g. patternProperties."^API_.*" key defines the pattern whose schema will be applied on any user provided key that match that pattern.

# @schema
# type: object
# patternProperties:
#   "^API_.*":
#     type: string
#     pattern: ^api-key
#   "^EMAIL_.*":
#     type: string
#     format: idn-email
# @schema
env:
  API_PROVIDER_ONE: api-key-xxxxx
  API_PROVIDER_TWO: api-key-xxxxx
  EMAIL_ADMIN: admin@example.org
  EMAIL_DEFAULT_USER: user@example.org

`anyOf`

Allows user to define multiple schema fo a single key. Key can be anyOf the given schemas or none of them.

# Accepts multiple types
# @schema
# anyOf:
#   - type: string
#   - type: integer
# minimum: 0
# @schema
foot: 1

# The above can be simplified with `type:`
# @schema
# type: [string, integer]
# minimum: 0
# @schema
fool: 1

# A pattern is also possible.
# In this case null or some string starting with foo.
# @schema
# anyOf:
#   - type: "null"
#   - pattern: ^foo
# @schema
bar:

`oneOf`

Allows user to define multiple schema fo a single key. Key must match oneOf the given schemas.

# @schema
# oneOf:
#   - type: integer
#   - pattern: Gib$
#   - pattern: gib$
# @schema
storage: 30Gib

`allOf`

Allows user to define multiple schema for a single key. Key must match oneOf the given schemas.

# @schema
# allOf:
#   - type: string
#     pattern: Gib$
#   - enum: [5Gib,10Gib,15Gib]
# @schema
storage: 10Gib

`not`

Allows to define a schema that must not be matched.

# @schema
# not:
#   type: string
# @schema
foo: bar

`if/then/else`

Conditional schema settings with if/then/else

# @schema
# anyOf:
#   - type: "null"
#   - type: string
# if:
#   type: "null"
# then:
#   description: It's a null value
# else:
#   description: It's a string
# @schema
unknown: foo

`minLength`

The value must be an integer greater or equal to zero and defines the minimum length of a string value.

# @schema
# minLength: 1
# @schema
namespace: foo

`maxLength`

The value must be an integer greater than zero and defines the maximum length of a string value.

# @schema
# maxLength: 3
# @schema
namespace: foo

`$ref`

The value must be an URI or relative file.

Relative files are imported on creation time. If you update the referenced file, you need to run helm-schema again.

foo.json:

{
  "foo": {
    "type": "string",
    "minLength": 10
  }
}

# @schema
# $ref: foo.json#/foo
# @schema
namespace: foo

is the same as

# @schema
# type: string
# minLength: 10
# @schema
namespace: foo

License

MIT

dadav / helm-schema

readme

helm-schema

Installation

Usage

Pre-commit hook

Running the binary directly

Options

Annotations

Available annotations

Validation & completion

helm-docs

Dependencies

Limitations

Examples

type

title

description

default

properties

pattern

format

required

deprecated

items

enum

const

examples

minimum

exclusiveMinimum

maximum

exclusiveMaximum

multipleOf

additionalProperties

patternProperties

anyOf

oneOf

allOf

not

if/then/else

minLength

maxLength

$ref