swapnikap/prototool

Your Swiss Army Knife for Protocol Buffers

prototool

Protobuf is one of the best interface description languages out there - it's widely adopted, and after over 15 years of use, it's practically bulletproof. However, working with Protobuf and maintaining consistency across your Protobuf files can be a pain - protoc, while being a tool that has stood the test of time, is non-trivial to use, and the Protobuf community has not developed common standards with regards to stub generation. Prototool aims to solve this by making working with Protobuf much simpler.

Prototool lets you:

• Handle installation of protoc and the import of all of the Well-Known Types behind the scenes in a platform-independent manner without any work on the part of the user.
• Standardize building of your Protobuf files with a common configuration, abstracting away all of the pain of protoc for you.
• Lint your Protobuf files with common linting rules according to Google' Style Guide, Uber's V1 Style Guide, or your own set of configured lint rules.
• Format your Protobuf files in a consistent manner.
• Create Protobuf files from a template that passes lint, taking care of package naming for you.
• Generate stubs using any plugin based on a simple configuration file, including handling imports of all the Well-Known Types.
• Call gRPC endpoints with ease, taking care of the JSON to binary conversion for you.
• Output errors and lint failures in a common file:line:column:message format, making integration with editors possible, Vim integration is provided out of the box.

Prototool accomplishes this by downloading and calling protoc on the fly for you, handing error messages from protoc and your plugins, and using the generated FileDescriptorSets for internal functionality, as well as wrapping a few great external libraries already in the Protobuf ecosystem. Compiling, linting and formatting commands run in around 3/100ths of second for a single Protobuf file, or under a second for a larger number (500+) of Protobuf files.

• Installation
• Quick Start
• Full Example
• Configuration
• File Discovery
• Command Overview
  • prototool config init
  • prototool compile
  • prototool generate
  • prototool lint
  • prototool format
  • prototool create
  • prototool files
  • prototool grpc
• gRPC Example
• Tips and Tricks
• Vim Integration
• Stability
• Development
• FAQ
  • Pre-Cache Protoc
  • Alpine Linux Issues
  • Managing External Plugins/Docker
  • Lint/Format Choices
• Special Thanks

Installation

Prototool can be installed on Mac OS X via Homebrew or Linux via Linuxbrew.

brew install prototool

This installs the prototool binary, along with bash completion, zsh completion, and man pages. You can also install all of the assets on Linux or without Homebrew from GitHub Releases.

curl -sSL https://github.com/uber/prototool/releases/download/v1.3.0/prototool-$(uname -s)-$(uname -m).tar.gz | \
  tar -C /usr/local --strip-components 1 -xz

If you do not want to install bash completion, zsh completion, or man mages, you can install just the prototool binary from GitHub Releases as well.

curl -sSL https://github.com/uber/prototool/releases/download/v1.3.0/prototool-$(uname -s)-$(uname -m) \
  -o /usr/local/bin/prototool && \
  chmod +x /usr/local/bin/prototool

You can also install the prototool binary using go get if using go1.11+ with module support enabled.

go get github.com/uber/prototool/cmd/prototool@dev

You may want to use gobin to install prototool outside of a module.

# Install to $GOBIN, or $GOPATH/bin if $GOBIN is not set, or $HOME/go/bin if neither are set
gobin github.com/uber/prototool/cmd/prototool@dev
# Install to /path/to/bin
GOBIN=/path/to/bin gobin github.com/uber/prototool/cmd/prototool@dev

Quick Start

We'll start with a general overview of the commands. There are more commands, and we will get into usage below, but this shows the basic functionality.

prototool help
prototool lint path/to/foo.proto path/to/bar.proto # file mode, specify multiple specific files
prototool lint idl/uber # directory mode, search for all .proto files recursively, obeying exclude_paths in prototool.yaml or prototool.json files
prototool lint # same as "prototool lint .", by default the current directory is used in directory mode
prototool create foo.proto # create the file foo.proto from a template that passes lint
prototool files idl/uber # list the files that will be used after applying exclude_paths from corresponding prototool.yaml or prototool.json files
prototool lint --list-linters # list all current lint rules being used
prototool lint --list-all-lint-groups # list all available lint groups, currently "google" and "uber"
prototool compile idl/uber # make sure all .proto files in idl/uber compile, but do not generate stubs
prototool generate idl/uber # generate stubs, see the generation directives in the config file example
prototool grpc idl/uber --address 0.0.0.0:8080 --method foo.ExcitedService/Exclamation --data '{"value":"hello"}' # call the foo.ExcitedService method Exclamation with the given data on 0.0.0.0:8080

Full Example

See the example directory.

The make command make example runs prototool while installing the necessary plugins.

Configuration

Prototool operates using a config file named either prototool.yaml or prototool.json. Only one of prototool.yaml or prototool.json can exist in a given directory. For non-trivial use, you should have a config file checked in to at least the root of your repository. It is important because the directory of an associated config file is passed to protoc as an include directory with -I, so this is the logical location your Protobuf file imports should start from.

Recommended base config file:

protoc:
  version: 3.6.1

The command prototool config init will generate a config file in the current directory with all available configuration options commented out except protoc.version. See etc/config/example/prototool.yaml for the config file that prototool config init --uncomment generates.

When specifying a directory or set of files for Prototool to operate on, Prototool will search for config files for each directory starting at the given path, and going up a directory until hitting root. If no config file is found, Prototool will use default values and operate as if there was a config file in the current directory, including the current directory with -I to protoc.

If multiple prototool.yaml or prototool.json files are found that match the input directory or files, an error will be returned.

File Discovery

In most Prototool commands, you will see help along the following lines:

$ prototool help lint
Lint proto files and compile with protoc to check for failures.

Usage:
  prototool lint [dirOrFile] [flags]

dirOrFile can take two forms:

• You can specify exactly one directory. If this is done, Prototool goes up until it finds a prototool.yaml or prototool.json file (or uses the current directory if none is found), and then uses this config for all .proto files under the given directory recursively, except for files in the excludes lists in prototool.yaml or prototool.json files.
• You can specify exactly one file. This has the effect as if you specified the directory of this file (using the logic above), but errors are only printed for that file. This is useful for e.g. Vim integration.
• You can specify nothing. This has the effect as if you specified the current directory as the directory.

The idea with "directory builds" is that you often need more than just one file to do a protoc call, for example if you have types in other files in the same package that are not referenced by their fully-qualified name, and/or if you need to know what directories to specify with -I to protoc (by default, the directory of the prototool.yaml or prototool.json file is used).

Command Overview

Let's go over some of the basic commands.

prototool config init

Create a prototool.yaml file in the current directory, with all options except protoc.version commented out.

prototool compile

Compile your Protobuf files, but do not generate stubs. This has the effect of calling protoc with -o /dev/null.

prototool generate

Compile your Protobuf files and generate stubs according to the rules in your prototool.yaml or prototool.json file.

See etc/config/example/prototool.yaml for all available options. There are special options available for Golang plugins, and plugins that output a single file instead of a set of files. Specifically, you can output a single JAR for the built-in protoc java plugin, and you can output a file with the serialized FileDescriptorSet using the built-in protoc descriptor_set plugin, optionally also calling --include_imports and/or --include_source_info.

See example/idl/uber/prototool.yaml for a full example.

prototool lint

Lint your Protobuf files.

Lint rules can be set using the configuration file. See the configuration at etc/config/example/prototool.yaml for all available options. There are two pre-configured groups of rules:

• google: This lint group follows the Style Guide at https://developers.google.com/protocol-buffers/docs/style. This is a small group of rules meant to enforce basic naming, and is widely followed. The style guide is copied to etc/style/google/google.proto.
• uber1: This lint group follows the V1 Style Guide at etc/style/uber1/uber1.proto. This is a very strict rule group and is meant to enforce consistent development patterns.
• uber2: This lint group is the V2 Style Guide, and makes some modifcations to more closely follow the Google Cloud APIs file structure, as well as adding even more rules to enforce more consistent development patterns. This lint group is under development.

To see the differences between lint groups, use the --diff-lint-groups flag:

prototool lint --diff-lint-groups google,uber2

Configuration of your group can be done by setting the lint.group option in your prototool.yaml file:

lint:
  group: google

See the prototool.yaml files at etc/style/google/prototool.yaml and etc/style/uber1/prototool.yaml for examples.

The uber lint group represents the default lint group, and will be used if no lint group is configured.

Linting also understands the concept of file headers, typically license headers. To specify a license header, add the following to your prototool.yaml:

lint:
  file_header:
    path: path/to/header.txt
    is_commented: true

The path option specifies the path to the file that contains the header data. The is_commented option specifies whether the header data is already commented, and if not, // will be added before all non-empty lines, and // will be added before all empty lines. is_commented is optional and generally will not be set if the file is not commented, for example if path points to a text LICENSE file.

If lint.file_header.path is set, prototool create, prototool format --fix, and prototool lint will all take the file header into account.

See internal/cmd/testdata/lint for additional examples of configurations, and run prototool lint internal/cmd/testdata/lint/DIR from a checkout of this repository to see example failures.

Files must be valid Protobuf that can be compiled with protoc, so prior to linting, prototool lint will compile your using protoc. Note, however, this is very fast - for the two files in etc/style/uber1, compiling and linting only takes approximately 3/100ths of a second:

$ time prototool lint etc/style/uber1

real	0m0.037s
user	0m0.026s
sys	0m0.017s

For all 694 Protobuf files currently in googleapis, this takes approximately 3/4ths of a second:

$ cat prototool.yaml
protoc:
  allow_unused_imports: true
lint:
  group: google

$ time prototool lint .

real	0m0.734s
user	0m3.835s
sys	0m0.924s

prototool format

Format a Protobuf file and print the formatted file to stdout. There are flags to perform different actions:

• -d Write a diff instead.
• -f Fix the file according to the Style Guide.
• -l Write a lint error in the form file:line:column:message if a file is unformatted.
• -w Overwrite the existing file instead.

Concretely, the -f flag can be used so that the values for java_multiple_files, java_outer_classname, and java_package are updated to reflect what is expected by the Google Cloud APIs file structure, and the value of go_package is updated to reflect what we expect for the Uber Style Guide. By formatting, the linting for these values will pass by default. See the documentation below for prototool create for an example.

prototool create

Create a Protobuf file from a template that passes lint. Assuming the filename example_create_file.proto, the file will look like the following:

syntax = "proto3";

package SOME.PKG;

option go_package = "PKGpb";
option java_multiple_files = true;
option java_outer_classname = "ExampleCreateFileProto";
option java_package = "com.SOME.PKG.pb";

This matches what the linter expects. SOME.PKG will be computed as follows:

• If --package is specified, SOME.PKG will be the value passed to --package.
• Otherwise, if there is no prototool.yaml or prototool.json that would apply to the new file, use uber.prototool.generated.
• Otherwise, if there is a prototool.yaml or prototool.json file, check if it has a packages setting under the create section (see etc/config/example/prototool.yaml for an example). If it does, this package, concatenated with the relative path from the directory with the prototool.yaml or prototool.json file will be used.
• Otherwise, if there is no packages directive, just use the relative path from the directory with the prototool.yaml or prototool.json file. If the file is in the same directory as the prototoo.yaml file, use uber.prototool.generated

For example, assume you have the following file at repo/prototool.yaml:

create:
  packages:
    - directory: idl
      name: uber
    - directory: idl/baz
      name: special

• prototool create repo/idl/foo/bar/bar.proto will have the package uber.foo.bar.
• prototool create repo/idl/bar.proto will have the package uber.
• prototool create repo/idl/baz/baz.proto will have the package special.
• prototool create repo/idl/baz/bat/bat.proto will have the package special.bat.
• prototool create repo/another/dir/bar.proto will have the package another.dir.
• prototool create repo/bar.proto will have the package uber.prototool.generated.

This is meant to mimic what you generally want - a base package for your idl directory, followed by packages matching the directory structure.

Note you can override the directory that the prototool.yaml or prototool.json file is in as well. If we update our file at repo/prototool.yaml to this:

create:
  packages:
    - directory: .
      name: foo.bar

Then prototool create repo/bar.proto will have the package foo.bar, and prototool create repo/another/dir/bar.proto will have the package foo.bar.another.dir.

If Vim integration is set up, files will be generated when you open a new Protobuf file.

prototool files

Print the list of all files that will be used given the input dirOrFile. Useful for debugging.

prototool grpc

Call a gRPC endpoint using a JSON input. What this does behind the scenes:

• Compiles your Protobuf files with protoc, generating a FileDescriptorSet.
• Uses the FileDescriptorSet to figure out the request and response type for the endpoint, and to convert the JSON input to binary.
• Calls the gRPC endpoint.
• Uses the FileDescriptorSet to convert the resulting binary back to JSON, and prints it out for you.

All these steps take on the order of milliseconds, for example the overhead for a file with four dependencies is about 30ms, so there is little overhead for CLI calls to gRPC.

gRPC Example

There is a full example for gRPC in the example directory. Run make init example to make sure everything is installed and generated.

Start the example server in a separate terminal by doing go run example/cmd/excited/main.go.

prototool grpc [dirOrFile] --address serverAddress --method package.service/Method --data 'requestData'

Either use --data 'requestData' as the the JSON data to input, or --stdin which will result in the input being read from stdin as JSON.

$ make init example # make sure everything is built just in case

$ prototool grpc example \
  --address 0.0.0.0:8080 \
  --method foo.ExcitedService/Exclamation \
  --data '{"value":"hello"}'
{
  "value": "hello!"
}

$ prototool grpc example \
  --address 0.0.0.0:8080 \
  --method foo.ExcitedService/ExclamationServerStream \
  --data '{"value":"hello"}'
{
  "value": "h"
}
{
  "value": "e"
}
{
  "value": "l"
}
{
  "value": "l"
}
{
  "value": "o"
}
{
  "value": "!"
}

$ cat input.json
{"value":"hello"}
{"value":"salutations"}

$ cat input.json | prototool grpc example \
  --address 0.0.0.0:8080 \
  --method foo.ExcitedService/ExclamationClientStream \
  --stdin
{
  "value": "hellosalutations!"
}

$ cat input.json | prototool grpc example \
  --address 0.0.0.0:8080 \
  --method foo.ExcitedService/ExclamationBidiStream \
  --stdin
{
  "value": "hello!"
}
{
  "value": "salutations!"
}

Tips and Tricks

Prototool is meant to help enforce a consistent development style for Protobuf, and as such you should follow some basic rules:

• Have all your imports start from the directory your prototool.yaml or prototool.json file is in. While there is a configuration option protoc.includes to denote extra include directories, this is not recommended.
• Have all Protobuf files in the same directory use the same package, and use the same values for go_package, java_multiple_files, java_outer_classname, and java_package.
• Do not use long-form go_package values, ie use foopb, not github.com/bar/baz/foo;foopb. This helps prototool generate do the best job.

Vim Integration

This repository is a self-contained plugin for use with the ALE Lint Engine. It should be similarly easy to add support for Syntastic, Neomake, etc.

The Vim integration will currently compile, provide lint errors, do generation of your stubs, and format your files on save. It will also optionally create new files from a template when opened.

The plugin is under vim/prototool, so your plugin manager needs to point there instead of the base of this repository. Assuming you are using vim-plug, copy/paste the following into your vimrc and you should be good to go. If you are using Vundle, just replace Plug with Vundle below.

" Prototool must be installed as a binary for the Vim integration to work.

" Add ale and prototool with your package manager.
" Note that Plug downloads from dev by default. There may be minor changes
" to the Vim integration on dev between releases, but this won't be common.
" To make sure you are on the same branch as your Prototool install, set
" the branch field in the options for uber/prototool per the vim-plug
" documentation. Vundle does not allow setting branches, so on Vundle,
" go into plug directory and checkout the branch of the release you are on.
Plug 'w0rp/ale'
Plug 'uber/prototool', { 'rtp':'vim/prototool' }

" We recommend setting just this for Golang, as well as the necessary set for proto.
" Note the 'prototool' linter is still available, but deprecated in favor of individual linters.
" Use the 'prototool-compile' linter to just compile, 'prototool-lint' to compile and lint,
" 'prototool-all' to compile, do generation of your stubs, and then lint.
let g:ale_linters = {
\   'go': ['golint'],
\   'proto': ['prototool-lint'],
\}
" We recommend you set this.
let g:ale_lint_on_text_changed = 'never'

" We generally have <leader> mapped to ",", uncomment this to set leader.
"let mapleader=","

" ,f will toggle formatting on and off.
" Change to PrototoolFormatFixToggle to toggle with --fix instead.
nnoremap <silent> <leader>f :call PrototoolFormatToggle()<CR>
" ,c will toggle create on and off.
nnoremap <silent> <leader>c :call PrototoolCreateToggle()<CR>

" Uncomment this to enable formatting by default.
"call PrototoolFormatEnable()
" Uncomment this to enable formatting with --fix by default.
"call PrototoolFormatFixEnable()
" Uncomment this to disable creating Protobuf files from a template by default.
"call PrototoolCreateDisable()

The recommended setup in short:

Plug 'w0rp/ale'
Plug 'uber/prototool', { 'rtp':'vim/prototool' }
let g:ale_linters = {
\   'go': ['golint'],
\   'proto': ['prototool-lint'],
\}
let g:ale_lint_on_text_changed = 'never'
call PrototoolFormatFixEnable()

Editor integration is a key goal of Prototool. We've demonstrated support internally for Intellij, and hope that we have integration for more editors in the future.

Stability

Prototool is generally available, and conforms to SemVer, so Prototool will not have any breaking changes on a given major version, with some exceptions:

• The output of the formatter may change between minor versions. This has not happened yet, but we may change the format in the future to reflect things such as max line lengths.
• The breaking change detector may have additional checks added between minor versions, and therefore a change that might not have been breaking previously might become a breaking change.
• The PACKAGE_NO_KEYWORDS linter on the uber2 lint group may have additional keywords added.
• The SERVICE_NAMES_NO_PLURALS linter on the uber2 lint group ignores certain plurals such as "data". We may add additional ignored plurals in the future, so plurals that are not ignored now may be ignored later.

Development

Prototool is under active development. If you want to help, here's some places to start:

• Try out prototool and file feature requests or bug reports.
• Submit PRs with any changes you'd like to see made.

We appreciate any input you have!

Before filing an issue or submitting a PR, make sure to review the Issue Guidelines, and before submitting a PR, make sure to also review the PR Guidelines. The Issue Guidelines will show up in the description field when filing a new issue, and the PR guidelines will show up in the description field when submitting a PR, but clear the description field of this pre-populated text once you've read it :-)

Note that development of Prototool will only work with Golang 1.10 or newer. On initially cloning the repository, run make init if you have not already to download dependencies to vendor.

Before submitting a PR, make sure to:

• Run make generate to make sure there is no diff.
• Run make to make sure all tests pass. This is functionally equivalent to the tests run on CI.

The entire implementation is purposefully under the internal package to not expose any API for the time being.

FAQ

Pre-Cache Protoc

Question: How do I download protoc ahead of time as part of a Docker build/CI pipeline?

Answer: prototool cache update.

You can pass both --cache-path and --config-data flags to this command to customize the invocation.

# Basic invocation which will cache using the default behavior. See prototool help cache update for more details.
prototool cache update
# Cache to a specific directory path/to/cache
prototool cache update --cache-path path/to/cache
# Cache using custom configuration data instead of finding a prototool.yaml file using the file discovery mechanism
prototool cache update --config-data '{"protoc":{"version":"3.6.1"}}'

There is also a command prototool cache delete which will delete all cached assets of prototool, however this command does not accept the --cache-path flag - if you specify a custom directory, you should clean it up on your own, we don't want to effectively call rm -rf DIR via a prototool command on a location we don't know about.

Alpine Linux Issues

Question: Help! Prototool is failing when I use it within a Docker image based on Alpine Linux!

Answer: apk add libc6-compat

protoc is not statically compiled, and adding this package fixes the problem.

Managing External Plugins/Docker

Question: Can Prototool manage my external plugins such as protoc-gen-go?

Answer: Unfortunately, no. This was an explicit design decision - Prototool is not meant to "know the world", instead Prototool just takes care of what it is good at (managing your Protobuf build) to keep Prototool simple, leaving you to do external plugin management. Prototool does provide the ability to use the "built-in" output directives cpp, csharp, java, js, objc, php, python, ruby provided by protoc out of the box, however.

If you want to have a consistent build environment for external plugins, we recommend creating a Docker image. Here's an example Dockerfile that results in a Docker image around 33MB that contains prototool, a cached protoc, and protoc-gen-go:

FROM golang:1.11.4-alpine3.8 AS build

ARG PROTOTOOL_VERSION=1.3.0
ARG PROTOC_VERSION=3.6.1
ARG PROTOC_GEN_GO_VERSION=1.2.0

RUN \
  apk update && \
  apk add curl git libc6-compat && \
  rm -rf /var/cache/apk/*
RUN \
  curl -sSL https://github.com/uber/prototool/releases/download/v$PROTOTOOL_VERSION/prototool-Linux-x86_64 -o /bin/prototool && \
  chmod +x /bin/prototool
RUN \
  mkdir /tmp/prototool-bootstrap && \
  echo $'protoc:\n  version:' $PROTOC_VERSION > /tmp/prototool-bootstrap/prototool.yaml && \
  echo 'syntax = "proto3";' > /tmp/prototool-bootstrap/tmp.proto && \
  prototool compile /tmp/prototool-bootstrap && \
  rm -rf /tmp/prototool-bootstrap
RUN go get github.com/golang/protobuf/... && \
  cd /go/src/github.com/golang/protobuf && \
  git checkout v$PROTOC_GEN_GO_VERSION && \
  go install ./protoc-gen-go

FROM alpine:3.8

WORKDIR /in

RUN \
  apk update && \
  apk add libc6-compat && \
  rm -rf /var/cache/apk/*

COPY --from=build /bin/prototool /bin/prototool
COPY --from=build /root/.cache/prototool /root/.cache/prototool
COPY --from=build /go/bin/protoc-gen-go /bin/protoc-gen-go

ENTRYPOINT ["/bin/prototool"]

Assuming this is in a file named Dockerfile in your current directory, build the image with:

docker build -t me/prototool-env .

Then, assuming you are in the directory you want to pass to Prototool and you want to run prototool compile, run:

docker run -v $(pwd):/in me/prototool-env compile

Lint/Format Choices

Question: I don't like some of the choices made in the Style Guide and that are enforced by default by the linter and/or I don't like the choices made in the formatter. Can we change some things?

Answer: Sorry, but we can't - The goal of Prototool is to provide a straightforward Style Guide and consistent formatting that minimizes various issues that arise from Protobuf usage across large organizations. There are pros and cons to many of the choices in the Style Guide, but it's our belief that the best answer is a single answer, sometimes regardless of what that single answer is.

We do have multiple lint groups available, see the help section on prototool lint above.

It is possible to ignore lint rules via configuration. However, especially if starting from a clean slate, we highly recommend using all default lint rules for consistency.

Many of the lint rules exist to mitigate backwards compatibility problems as schemas evolves. For example: requiring a unique request-response pair per RPC - while this potentially resuls in duplicated messages, this makes it impossible to affect an adjacent RPC by adding or modifying an existing field.

Special Thanks

Prototool uses some external libraries that deserve special mention and thanks for their contribution to Prototool's functionality:

• github.com/emicklei/proto - The Golang Protobuf parsing library that started it all, and is still used for the linting and formatting functionality. We can't thank Ernest Micklei enough for his help and putting up with all the filed issues.
• github.com/jhump/protoreflect - Used for the JSON to binary and back conversion. Josh Humphries is an amazing developer, thank you so much.
• github.com/fullstorydev/grpcurl - Still used for the gRPC functionality. Again a thank you to Josh Humphries and the team over at FullStory for their work.