A generator for protocol buffer described APIs for and in Go.

This is a generator for API client libraries for APIs specified by protocol buffers, such as those inside Google. It takes a protocol buffer (with particular annotations) and uses it to generate a client library.

We aim for this generator to replace the older monolithic generator. Some areas we hope to improve over the old generator are:

• using explicit normalized format for specifying APIs,
• simpler, faster implementation, and
• better error reporting.

go get github.com/googleapis/gapic-generator-go/cmd/protoc-gen-go_gapic. If you are using Go 1.11 and see error cannot find main module, see this FAQ page.

Or to install from source:

git pull https://github.com/googleapis/gapic-generator-go.git
cd gapic-generator-go
go install ./cmd/protoc-gen-go_gapic

The generator works as a protoc plugin, get protoc from google/protobuf.

protoc --go_gapic_out [OUTPUT_DIR] --go_gapic_opt 'go-gapic-package=package/path/url;name' a.proto b.proto

The go_gapic_opt flag is necessary because we need to know where to generated file will live. The substring before the equal sign is the name of this configuration option. The substring between the equal sign and the semicolon is the import path of the package, e.g. github.com/username/awesomeness. The substring after the semicolon is the name of the package used in the package statement. Idiomatically the name is last element of the path but it need not be. For instance, the last element of the path might be the package's version, and the package would benefit from a more descriptive name.

The generator can also be executed via a Docker container. The image containes protoc, the microgenerator binary, and the standard API protos.

$ docker run \
  --rm \
  --user $UID \
  --mount type=bind,source=</abs/path/to/protos>,destination=/in,readonly \
  --mount type=bind,source=$GOPATH/src,destination=/out/ \
  gcr.io/gapic-images/gapic-generator-go \
  --go-gapic-package "<github.com/package/import/path;name>"

Replace /abs/path/to/protos with the absolute path to the input protos and github.com/package/import/path;name with the desired import path & name for the gapic, as described in Invocation.

For convenience, the gapic.sh script wraps the above docker invocation. An equivalent invocation using gapic.sh is:

$ gapic.sh \
  --image gcr.io/gapic-images/gapic-generator-go \
  --in /abs/path/to/protos \
  --out $GOPATH/src\ 
  --go-gapic-package "<github.com/package/import/path;name>"

Use gapic.sh --help to print the usage documentation.

This generator is currently experimental. Please don't use it for anything mission-critical.

The generator itself supports the latest version.

The generated code is compatible with Go 1.6.