11 unstable releases (3 breaking)
|0.3.1||Nov 14, 2022|
|0.3.0||Aug 8, 2022|
|0.2.0||Jun 23, 2022|
|0.1.6||Jun 19, 2022|
|0.0.1||Mar 28, 2022|
#959 in Encoding
7,763 downloads per month
protoc plugin that generates Cargo crates and include files.
When used in projects that use only Rust code, the preferred mechanism for
generating protobuf definitions with Prost! is to use
build.rs file. However, when working in polyglot environments,
it can be advantageous to utilize common tooling in the Protocol Buffers
ecosystem. One common tool used for this purpose is buf, which simplifies
the code generation process and includes several useful features, including
linting, package management, and breaking change detection.
protoc-gen-prost-crate has been installed within a directory on your
$PATH. Then invoke
protoc from the command line as follows:
protoc --prost-crate_out=proto/gen -I proto proto/greeter/v1/greeter.proto
The following options can be specified:
default_package_filename=<value>: This should match the value of the main
protoc-gen-proststep so that the include file references the correct output file. (see also default package filename from prost-build)
include_file(=<value>): Sets the name for the generated include file. If not specified, then the default value depends on whether
gen_crateis specified. If it is, then
src/lib.rs. Otherwise, it defaults to
mod.rs. The generated include file will add feature markers to each produced module to allow for faster compilation and reduced sizes for unnecessary features. This can be disabled by specifying
only_include=<proto_path>: Will only include packages with the specified prefix in the generated include file and generated features list, if enabled. Paths must be fully-qualified and begin with
gen_crate(=<template_path>): Indicates that a Cargo crate should be generated with the manifest based on the template at the path provided. The template should include a placeholder to inject the crate features graph unless
no_featuresis specified. The template generation does not take into account crate dependencies. These must be managed separately. If not specified,
Cargo.tomlis assumed. This allows automatic updating of the features in the Cargo manifest.
no_features(=<boolean>): Disables the generation of feature flags in the include file or in the Cargo manifest.
package_separator=[-_.+]: Changes the character used to separate parts of a package name when used as a feature flag. Defaults to
-if not specified. Note:
.results in feature names that are not legal for publishing to crates.io.
A note on parameter values:
(=<boolean>): Boolean values may be specified after a parameter, but if not, the value is assumed to be
trueby virtue of having listed the parameter.
Usage with buf
When used with buf, options can be specified in the
This plugin must be run with
strategy: all in order to have a complete
view of the protobuf schemas and correctly identify dependencies for the
The following will just produce an include file
mod.rs in the output
directory without any conditional compilation feature flags:
version: v1 plugins: - name: prost-crate out: gen strategy: all opt: - no_features
When using the
gen_crate option, later Rust generators should generate
src directory which will be created by this plugin:
version: v1 plugins: - name: prost out: gen/src opt: - bytes=. - file_descriptor_set - name: prost-crate out: gen strategy: all opt: - gen_crate
When working with private, vendored package dependencies, buf tends to
push more files for output than desired. To limit the packages that get
put into the include file, used the
version: v1 plugins: - name: prost out: gen/src opt: - bytes=. - file_descriptor_set - name: prost-crate out: gen strategy: all opt: - gen_crate - only_include=.my_company
protoc-gen-prost-crate plugin is also published on the Buf Schema Registry as
a plugin which you can execute remotely, without needing to explicitly install
this tool. See the plugin listing to identify the latest published version
for use. Note that the remote plugin form is not compatible with the
option, as the plugin is executed outside the context of the current file system,
so template information cannot be used. The plugin is referenced as follows:
version: v1 plugins: - remote: buf.build/prost/plugins/crate:v0.1.6-1 out: gen
Cargo manifest template
When using the
gen_crate option, the template specified will be placed in
the output folder. The template should include a commented insertion point
that can be referenced for the placement of the features dependency graph.
The template will be
Cargo.toml by default, and will do an in-place update
Cargo.toml file, updating the exposed features to match the generated
protoc will insert the computed dependency graph above the insertion point.
If this commented line is not included, then
protoc will not know where to
place the features list and the insertion will be silently skipped.
[package] name = "my-cool-proto-defs" version = "0.1.0" edition = "2021" [dependencies] prost = "0.10.0" [features] default =  ## @@protoc_insertion_point(features)
Once generated, the manifest will include a set of features that allow limiting the compilation to only those modules that are required. Each feature will automatically activate the relevant features required.
[package] name = "my-cool-proto-defs" version = "0.1.0" edition = "2021" [dependencies] prost = "0.10.0" [features] default =  ## @@protoc_deletion_point(features) ## This section is automatically generated by protoc-gen-prost-crate. ## Changes in this area may be lost on regeneration. proto_full = ["helloworld-v1", "greeter-v1"] "greeter-v1" = ["helloworld-v1"] "helloworld-v1" =  ## @@protoc_insertion_point(features)
Customizing after generation
In general, I counsel against manually editing the generated code files. Doing
so makes it more difficult to evolve your schema, as regenerating the code
will result in needing to manually edit again in order to re-add the
customizations. Instead, I recommend using a subdirectory to host the generated
code and include that file in
src/lib.rs as in the
include!("gen/mod.rs"); // Any additional traits or other impls can go here or in other related files. // These won't be touched by the code generation process.
Cargo.toml (prior to first generation):
[package] name = "my-cool-proto-defs" version = "0.1.0" edition = "2021" [features] default = ["proto_full"] ## @@protoc_insertion_point(features) [dependencies] prost = "0.10.0"
version: v1 plugins: - name: prost out: src opt: - bytes=. - file_descriptor_set - name: prost-crate out: gen strategy: all opt: - include_file=src/gen/mod.rs - gen_crate