Every component's documentation should include a brief description of the component and guidance on how to use it. There is also some information about the component (or metadata) that should be included to help end-users understand the current state of the component and whether it is right for their use case. Examples of this metadata about a component are:
- its stability level
- the distributions containing it
- the types of pipelines it supports
- metrics emitted in the case of a scraping receiver
The metadata generator defines a schema for specifying this information to ensure it is complete and well-formed. The metadata generator is then able to ingest the metadata, validate it against the schema and produce documentation in a standardized format. An example of how this generated documentation looks can be found in documentation.md.
In order for a component to benefit from the metadata generator (mdatagen
) these requirements need to be met:
- A
metadata.yaml
file containing the metadata needs to be included in the component - The component should declare a
go:generate mdatagen
directive which tellsmdatagen
what to generate
As an example, here is a minimal metadata.yaml
for the OTLP receiver:
type: otlp
status:
class: receiver
stability:
beta: [logs]
stable: [metrics, traces]
Detailed information about the schema of metadata.yaml
can be found in metadata-schema.yaml.
The go:generate mdatagen
directive is usually defined in a doc.go
file in the same package as the component, for example:
//go:generate mdatagen metadata.yaml
package main
Below are some more examples that can be used for reference:
- The ElasticSearch receiver has an extensive metadata.yaml
- The host metrics receiver has internal subcomponents, each with their own
metadata.yaml
anddoc.go
. See cpuscraper for example.
You can run cd cmd/mdatagen && $(GOCMD) install .
to install the mdatagen
tool in GOBIN
and then run mdatagen metadata.yaml
to generate documentation for a specific component or you can run make generate
to generate documentation for all components.
The code for generating the documentation can be found in loader.go and the templates for rendering the documentation can be found in templates. When making updates to the metadata generator or introducing support for new functionality:
- Ensure the metadata-schema.yaml and ./metadata.yaml files reflect the changes.
- Run
make mdatagen-test
. - Make sure all tests are passing including generated tests.
- Run
make generate
.