yaml-docs

=========

The yaml-docs tool auto-generates documentation from yaml files into markdown files as a table with each of the files values, their defaults, and an optional description parsed from comments.

Note: This was originally forked from norwoodj/helm-docs, which is build around Helm charts, and there are a number of hold-overs in the examples and naming.

Usage

Usage:
  yaml-docs [flags]

Flags:
  -d, --dry-run                    don't actually render any markdown files just print to stdout passed
  -h, --help                       help for yaml-docs
  -l, --log-level string           Level of logs that should printed, one of (panic, fatal, error, warning, info, debug, trace) (default "info")
  -o, --output-file string         markdown file path relative to input template to which rendered documentation will be written (default "README.md")
  -s, --sort-values-order string   order in which to sort the values table ("alphanum" or "file") (default "alphanum")
  -t, --template-files strings     gotemplate file paths relative to each chart directory from which documentation will be generated (default [README.md.gotmpl])
  -f, --values-file strings        yaml values file to be parsed into values table. Can be specified multiple times

The markdown generation is entirely gotemplate driven. The tool parses metadata from charts and generates a number of sub-templates that can be referenced in a template file (by default README.md.gotmpl). If no template file is provided, the tool has a default internal template that will generate a reasonably formatted README.

The most useful aspect of this tool is the auto-detection of field descriptions from comments:

config:
  databasesToCreate:
    # -- default database for storage of database metadata
    - postgres

    # -- database for the [hashbash](https://github.com/norwoodj/hashbash-backend-go) project
    - hashbash

  usersToCreate:
    # -- admin user
    - {name: root, admin: true}

    # -- user with access to the database with the same name
    - {name: hashbash, readwriteDatabases: [hashbash]}

statefulset:
  image:
    # -- Image to use for deploying, must support an entrypoint which creates users/databases from appropriate config files
    repository: jnorwood/postgresql
    tag: "11"

  # -- Additional volumes to be mounted into the database container
  extraVolumes:
    - name: data
      emptyDir: {}

Resulting in a resulting README section like so:

Key	Type	Default	Description
config.databasesToCreate[0]	string	"postgresql"	default database for storage of database metadata
config.databasesToCreate[1]	string	"hashbash"	database for the hashbash project
config.usersToCreate[0]	object	{"admin":true,"name":"root"}	admin user
config.usersToCreate[1]	object	{"name":"hashbash","readwriteDatabases":["hashbash"]}	user with access to the database with the same name
statefulset.extraVolumes	list	[{"emptyDir":{},"name":"data"}]	Additional volumes to be mounted into the database container
statefulset.image.repository	string	"jnorwood/postgresql:11"	Image to use for deploying, must support an entrypoint which creates users/databases from appropriate config files
statefulset.image.tag	string	"18.0831"

You'll notice that some complex fields (lists and objects) are documented while others aren't, and that some simple fields like statefulset.image.tag are documented even without a description comment. The rules for what is and isn't documented in the final table will be described in detail later in this document.

Installation

To build from source in this repository:

cd cmd/yaml-docs
go build

Or install from source:

GO111MODULE=on go get github.com/andbron/yaml-docs/cmd/yaml-docs

Usage

Pre-commit hook

If you want to automatically generate README.md files with a pre-commit hook, make sure you install the pre-commit binary, and add a .pre-commit-config.yaml file to your project. Then run:

pre-commit install
pre-commit install-hooks

Future changes to your project's yaml or README.md.gotmpl files will cause an update to documentation when you commit.

Running the binary directly

To run and generate documentation into READMEs:

yaml-docs -f my-values.yaml
# OR
yaml-docs --dry-run # prints generated documentation to stdout rather than modifying READMEs

Markdown Rendering

--template-files specifies the list of gotemplate files that should be used in rendering the resulting markdown file for each chart found. By default --template-files=README.md.gotmpl.

Files are always interpreted as being relative to the working directory.

If any of the specified template files is not found for a chart (you'll notice most of the example charts do not have a README.md.gotmpl) file, then the internal default template is used instead.

The tool also includes the sprig templating library, so those functions can be used in the templates you supply.

values.yaml metadata

This tool can parse descriptions and defaults of values from values.yaml files. The defaults are pulled directly from the yaml in the file.

It was formerly the case that descriptions had to be specified with the full path of the yaml field. This is no longer the case, although it is still supported. Where before you would document a values.yaml like so:

controller:
  publishService:
    # controller.publishService.enabled -- Whether to expose the ingress controller to the public world
    enabled: false

  # controller.replicas -- Number of nginx-ingress pods to load balance between.
  # Do not set this below 2.
  replicas: 2

You may now equivalently write:

controller:
  publishService:
    # -- Whether to expose the ingress controller to the public world
    enabled: false

  # -- Number of nginx-ingress pods to load balance between.
  # Do not set this below 2.
  replicas: 2

New-style comments are much the same as the old-style comments, except that while old comments for a field could appear anywhere in the file, new-style comments must appear on the line(s) immediately preceding the field being documented.

I invite you to check out the example-charts to see how this is done in practice. The but-auto-comments examples in particular document the new comment format.

Note that comments can continue on the next line. In that case leave out the double dash, and the lines will simply be appended with a space in-between, as in the controller.replicas field in the example above

The following rules are used to determine which values will be added to the values table in the README:

• By default, only leaf nodes, that is, fields of type int, string, float, bool, empty lists, and empty maps are added as rows in the values table. These fields will be added even if they do not have a description comment
• Lists and maps which contain elements will not be added as rows in the values table unless they have a description comment which refers to them
• Adding a description comment for a non-empty list or map in this way makes it so that leaf nodes underneath the described field will not be automatically added to the values table. In order to document both a non-empty list/map and a leaf node within that field, description comments must be added for both

e.g. In this case, both controller.livenessProbe and controller.livenessProbe.httpGet.path will be added as rows in the values table, but controller.livenessProbe.httpGet.port will not

controller:
  # -- Configure the healthcheck for the ingress controller
  livenessProbe:
    httpGet:
      # -- This is the liveness check endpoint
      path: /healthz
      port: http

Results in:

Key	Type	Default	Description
controller.livenessProbe	object	{"httpGet":{"path":"/healthz","port":8080}}	Configure the healthcheck for the ingress controller
controller.livenessProbe.httpGet.path	string	"/healthz"	This is the liveness check endpoint

If we remove the comment for controller.livenessProbe however, both leaf nodes controller.livenessProbe.httpGet.path and controller.livenessProbe.httpGet.port will be added to the table, with or without description comments:

controller:
  livenessProbe:
    httpGet:
      # -- This is the liveness check endpoint
      path: /healthz
      port: http

Results in:

Key	Type	Default	Description
controller.livenessProbe.httpGet.path	string	"/healthz"	This is the liveness check endpoint
controller.livenessProbe.httpGet.port	string	"http"

nil values

If you would like to define a key for a value, but leave the default empty, you can still specify a description for it as well as a type. This is possible with both the old and the new comment format:

controller:
  # -- (int) Number of nginx-ingress pods to load balance between
  replicas:
  
  # controller.image -- (string) Number of nginx-ingress pods to load balance between
  image:

This could be useful when wanting to enforce user-defined values for the chart, where there are no sensible defaults.

Default values/column

In cases where you do not want to include the default value from values.yaml, or where the real default is calculated inside the chart, you can change the contents of the column like so:

service:
  # -- Add annotations to the service, this is going to be a long comment across multiple lines
  # but that's fine, these will be concatenated and the @default will be rendered as the default for this field
  # @default -- the chart will add some internal annotations automatically
  annotations: []

The order is important. The first comment line(s) must be the one specifying the key or using the auto-detection feature and the description for the field. The @default comment must follow.

See here for an example.

Spaces and Dots in keys

In the old-style comment, if a key name contains any "." or " " characters, that section of the path must be quoted in description comments e.g.

service:
  annotations:
    # service.annotations."external-dns.alpha.kubernetes.io/hostname" -- Hostname to be assigned to the ELB for the service
    external-dns.alpha.kubernetes.io/hostname: stupidchess.jmn23.com

configMap:
  # configMap."not real config param" -- A completely fake config parameter for a useful example
  not real config param: value