87 lines
2.9 KiB
Markdown
87 lines
2.9 KiB
Markdown
# `protoc-gen-gotemplate`
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:open_file_folder: protocol generator + golang text/template (protobuf)
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A generic **code**/script/data generator based on [Protobuf](https://developers.google.com/protocol-buffers/).
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---
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This is a generator plugin for the Google Protocol Buffers compiler (`protoc`).
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The plugin parses **protobuf** files, generates an **ast**, and walks a local **templates directory** to generate files using the [Golang's `text/template` engine](https://golang.org/pkg/text/template/).
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## Philosophy
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* protobuf-first
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* no built-in template, only user defined templates
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* kiss, *keep it stupid simple*
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## Under the hood
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1. the *user* `protobuf` files are parsed by [`protoc`](https://github.com/google/protobuf/releases)
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2. the `ast` is generated by [`protoc-gen-go` helpers](https://github.com/golang/protobuf/tree/master/protoc-gen-go)
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3. the `ast` is given to [Golang's `text/template` engine](https://golang.org/pkg/text/template/) for each *user* template files
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4. the *funcmap* enriching the template engine is based on [Masterminds/sprig](https://github.com/Masterminds/sprig), and contains type-manipulation, iteration and language-specific helpers
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## Usage
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`protoc-gen-gotemplate` requires a **template_dir** directory *(by default `./templates`)*.
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Every files ending with `.tmpl` will be processed and written in the destination folder, following the file hierarchy of the `template_dir`, and removing the `.tmpl` extension.
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---
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```console
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$> ls -R
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input.proto templates/doc.txt.tmpl templates/config.json.tmpl
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$> protoc --gotemplate_out=. input.proto
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$> ls -R
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input.proto templates/doc.txt.tmpl templates/config.json.tmpl
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doc.txt config.json
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```
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---
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You can specify a custom `template_dir` or enable `debug`:
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```console
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$> protoc --gotemplate_out=debug=true,template_dir=/path/to/template/directory:. input.proto
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```
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---
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See [examples](./examples).
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## Funcmap
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This project uses [Masterminds/sprig](https://github.com/Masterminds/sprig) library and additional functions to extend the builtin [text/template](https://golang.org/pkg/text/template) helpers.
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Non-exhaustive list of new helpers:
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* **all the functions from [sprig](https://github.com/Masterminds/sprig)**
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* `json`
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* `prettyjson`
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* `first`
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* `last`
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See the project helpers for the complete list.
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## Hacks
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## Install
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* Install the **Go** compiler and tools from https://golang.org/doc/install
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* Install **protobuf**: `go get -u github.com/golang/protobuf/{proto,protoc-gen-go}`
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* Install **protoc-gen-gotemplate**: `go get -u github.com/moul/protoc-gen-gotemplate`
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## Projects using `protoc-gen-gotemplate`
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* [kafka-gateway](https://github.com/moul/kafka-gateway/): Kafka gateway/proxy (gRPC + http) using Go-Kit
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* [translator](https://github.com/moul/translator): Translator Micro-service using Gettext and Go-Kit
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* [acl](https://github.com/moul/acl): ACL micro-service (gRPC/protobuf + http/json)
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## License
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MIT
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