protoc-gen-gotemplate

📂 protocol generator + golang text/template (protobuf)

A generic code/script/data generator based on Protobuf.

---

This project is a generator plugin for the Google Protocol Buffers compiler (protoc).

The plugin parses protobuf files, generates an ast, and walks a local templates directory to generate files using the Golang's text/template engine.

Philosophy

• protobuf-first
• no built-in template, only user defined templates
• kiss, keep it stupid simple

Under the hood

1. the user protobuf files are parsed by protoc
2. the ast is generated by protoc-gen-go helpers
3. the ast is given to Golang's text/template engine for each user template files
4. the funcmap enriching the template engine is based on Masterminds/sprig, and contains type-manipulation, iteration and language-specific helpers

Usage

protoc-gen-gotemplate requires a template_dir directory (by default ./templates).

Every file ending with .tmpl will be processed and written to the destination folder, following the file hierarchy of the template_dir, and remove the .tmpl extension.

---

$> ls -R
input.proto     templates/doc.txt.tmpl      templates/config.json.tmpl
$> protoc --gotemplate_out=. input.proto
$> ls -R
input.proto     templates/doc.txt.tmpl      templates/config.json.tmpl
doc.txt         config.json

---

You can specify a custom template_dir or enable debug:

$> protoc --gotemplate_out=debug=true,template_dir=/path/to/template/directory:. input.proto

---

Hints

Shipping the templates with your project is very smart and useful when contributing on git-based projects.

Another workflow consists in having a dedicated repository for generic templates which is then versioned and vendored with multiple projects (npm package, golang vendor package, ...)

See examples.

Funcmap

This project uses Masterminds/sprig library and additional functions to extend the builtin text/template helpers.

Non-exhaustive list of new helpers:

• all the functions from sprig
• json
• prettyjson
• first
• last

See the project helpers for the complete list.

Install

• Install the Go compiler and tools from https://golang.org/doc/install
• Install protobuf: go get -u github.com/golang/protobuf/{proto,protoc-gen-go}
• Install protoc-gen-gotemplate: go get -u github.com/moul/protoc-gen-gotemplate

Projects using protoc-gen-gotemplate

• kafka-gateway: Kafka gateway/proxy (gRPC + http) using Go-Kit
• translator: Translator Micro-service using Gettext and Go-Kit
• acl: ACL micro-service (gRPC/protobuf + http/json)

License

MIT