Receivers can contain a metadata.yaml file that documents the metrics that may be emitted by the receiver.
Current examples:
See metric-metadata.yaml for file format documentation.
If adding a new receiver a codegen.go file should also be added to trigger the generation. See below for details.
When go generate is run (it is run automatically in the make build targets) there are a few special build directives in codegen.go files:
make install-tools results in cmd/mdatagen being installed to GOBIN
/receiver/hostmetricsreceiver/codegen.go Runs mdatagen for the hostmetricsreceiver metadata.yaml which generates /receiver/hostmetricsreceiver/internal/metadata package which has Go files containing metric and label metadata.