GRPC golang output path

go code output path

The protocol buffer compiler produces Go output when invoked with the go_out flag. The argument to the go_out flag is the directory where you want the compiler to write your Go output. The compiler creates a single source file for each .proto file input. The name of the output file is created by replacing the .proto extension with .pb.go.

Where in the output directory the generated .pb.go file is placed depends on the compiler flags. There are several output modes:

  • If the paths=import flag is specified, the output file is placed in a directory named after the Go package’s import path. For example, an input file protos/buzz.proto with a Go import path of example.com/project/protos/fizz results in an output file at example.com/project/protos/fizz/buzz.pb.go. This is the default output mode if a paths flag is not specified.
  • If the module=$PREFIX flag is specified, the output file is placed in a directory named after the Go package’s import path, but with the specified directory prefix removed from the output filename. For example, an input file protos/buzz.proto with a Go import path of example.com/project/protos/fizz and example.com/project specified as the module prefix results in an output file at protos/fizz/buzz.pb.go. Generating any Go packages outside the module path results in an error. This mode is useful for outputting generated files directly into a Go module.
  • If the paths=source_relative flag is specified, the output file is placed in the same relative directory as the input file. For example, an input file protos/buzz.proto results in an output file at protos/buzz.pb.go

code structure

The directory tree looks like this:

❯ exa -l --tree
drwxr-xr-x    - dylan 15 Feb 10:49 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 10:49 ├── protos
.rw-r--r--  365 dylan 15 Feb 10:48 │  └── greeting.proto
.rw-r--r-- 1.4k dylan 15 Feb 10:40 └── README.md

--go_out=paths=import

Using --go_out=paths=import to generate code into import path.

❯ protoc --go_out=. --go_opt=paths=import --go-grpc_out=. --go-grpc_opt=paths=import protos/*.proto

❯ exa -l --tree
drwxr-xr-x    - dylan 15 Feb 11:21 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
drwxr-xr-x    - dylan 15 Feb 11:21 ├── github.com
drwxr-xr-x    - dylan 15 Feb 11:21 │  └── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:21 │     └── greeting
.rw-r--r-- 7.2k dylan 15 Feb 11:21 │        ├── greeting.pb.go
.rw-r--r-- 3.7k dylan 15 Feb 11:21 │        └── greeting_grpc.pb.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 11:20 ├── protos
.rw-r--r--  365 dylan 15 Feb 10:48 │  └── greeting.proto
.rw-r--r-- 1.4k dylan 15 Feb 10:40 └── README.md

You can write generated code into different places. Here we put in whatever folder.

mkdir -p whatever
protoc --go_out=whatever --go_opt=paths=import --go-grpc_out=. --go-grpc_opt=paths=import protos/*.proto

The directory tree looks like this:

drwxr-xr-x    - dylan 15 Feb 11:22 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
drwxr-xr-x    - dylan 15 Feb 11:21 ├── github.com
drwxr-xr-x    - dylan 15 Feb 11:21 │  └── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:21 │     └── greeting
.rw-r--r-- 7.2k dylan 15 Feb 11:21 │        ├── greeting.pb.go
.rw-r--r-- 3.7k dylan 15 Feb 11:22 │        └── greeting_grpc.pb.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 11:20 ├── protos
.rw-r--r--  365 dylan 15 Feb 10:48 │  └── greeting.proto
.rw-r--r-- 1.4k dylan 15 Feb 10:40 ├── README.md
drwxr-xr-x    - dylan 15 Feb 11:22 └── whatever
drwxr-xr-x    - dylan 15 Feb 11:22    └── github.com
drwxr-xr-x    - dylan 15 Feb 11:22       └── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:22          └── greeting
.rw-r--r-- 7.2k dylan 15 Feb 11:22             └── greeting.pb.go

--go_out=module=$PREFIX

We can put generated go code and grpc code into path, with specific directory prefix removed. Here we remove github.com directory and use grpc-greeting as the root path.

protoc --go_out=. --go_opt=module=github.com --go-grpc_out=. --go-grpc_opt=paths=import protos/*.proto

The directory tree looks like this:

drwxr-xr-x    - dylan 15 Feb 11:31 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
drwxr-xr-x    - dylan 15 Feb 11:31 ├── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:31 │  └── greeting
.rw-r--r-- 7.2k dylan 15 Feb 11:31 │     ├── greeting.pb.go
.rw-r--r-- 3.7k dylan 15 Feb 11:31 │     └── greeting_grpc.pb.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 11:20 ├── protos
.rw-r--r--  365 dylan 15 Feb 10:48 │  └── greeting.proto
.rw-r--r-- 1.4k dylan 15 Feb 10:40 └── README.md

We can also put generated go code and grpc code into different path.

protoc --go_out=. --go_opt=module=github.com --go-grpc_out=. --go-grpc_opt=paths=import protos/*.proto

The directory tree looks like this:

❯ exa -l --tree
drwxr-xr-x    - dylan 15 Feb 11:27 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
drwxr-xr-x    - dylan 15 Feb 11:27 ├── github.com
drwxr-xr-x    - dylan 15 Feb 11:27 │  └── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:27 │     └── greeting
.rw-r--r-- 3.7k dylan 15 Feb 11:27 │        └── greeting_grpc.pb.go
drwxr-xr-x    - dylan 15 Feb 11:27 ├── grpc-greeting
drwxr-xr-x    - dylan 15 Feb 11:27 │  └── greeting
.rw-r--r-- 7.2k dylan 15 Feb 11:27 │     └── greeting.pb.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 11:20 ├── protos
.rw-r--r--  365 dylan 15 Feb 10:48 │  └── greeting.proto
.rw-r--r-- 1.4k dylan 15 Feb 10:40 └── README.md

--go_out=paths=source_relative

Using --go_out=paths=source_relative to generate code into the same relative directory as the input path.

protoc --go_out=. --go_opt=paths=source_relative --go-grpc_out=. --go-grpc_opt=paths=source_relative protos/*.proto

The directory tree looks like this:

❯ exa -l --tree
drwxr-xr-x    - dylan 15 Feb 10:49 .
drwxr-xr-x    - dylan 15 Feb 10:27 ├── cmd
drwxr-xr-x    - dylan 15 Feb 10:28 │  └── greeting-server
.rw-r--r--   30 dylan 15 Feb 10:28 │     └── main.go
.rw-r--r--  250 dylan 15 Feb 10:49 ├── Makefile
drwxr-xr-x    - dylan 15 Feb 11:19 ├── protos
.rw-r--r-- 7.2k dylan 15 Feb 11:19 │  ├── greeting.pb.go
.rw-r--r--  365 dylan 15 Feb 10:48 │  ├── greeting.proto
.rw-r--r-- 3.7k dylan 15 Feb 11:19 │  └── greeting_grpc.pb.go
.rw-r--r-- 1.4k dylan 15 Feb 10:40 └── README.md