I have a library called myProtos which looks like this
.
|-- proto
|---- hello.proto
|
|-- generated
└---- hello.pb.go
I have a .proto file outside called example.proto that should import hello.proto
So the top of the file looks like this:
syntax = "proto3";
package example;
import "path/to/myProtos/proto/hello.proto"
Now, when I compile example.proto I get an import error on example.pb.go because it has the import line import "path/to/myProtos/proto/hello.pb.go"
I tried adding both import paths, but I get an 'import but not used error'. I also tried doing relative imports and passing both directories as flags to protoc, which worked, but I need the import path in the go file to be absolute.
How can I tell protoc that on the go file the path is different?
Is there a better 'best practice' in this case?
What worked for me is to define option go_package = "github.com/<your-account>/<your-cool-project>/<sub-dirs>
Let's assume you have the folder structure your stated:
.
|-- proto
|---- hello.proto
|
|-- generated
└---- hello.pb.go
In your case you would add option go_package = "<path>/<in>/<GOPATH>/generated" to hello.proto.
What is important is that you then have to run
protoc -I. --go_out=$GOPATH ./*.proto
Generally, I would generate the go files alongside the proto files to keep the import paths the same for proto and go files. But this might be a matter of taste. In that case you would then simply set option go_package = "<path>/<in>/<GOPATH>/proto" to hello.proto.
In both cases a relative import of the .proto file should now resolve to the proper import in the generated Go code and the .pb.go files should also be put into the proper Go package folders.
Use package generated; inside your hello.proto file.
Then, protoc -I proto/ proto/*.proto --go_out=generated will generate a hello.pb.go inside generated folder by the package name of generated.
The package inside the proto files tells the protobuf generator which package to use inside the generated file.
Related
From here:
https://developers.google.com/protocol-buffers/docs/reference/go-generated#package
It is written:
There is no correlation between the Go import path and the package
specifier in the .proto file. The latter is only relevant to the
protobuf namespace, while the former is only relevant to the Go
namespace. Also, there is no correlation between the Go import path
and the .proto import path.
So, if I understand correctly - the "package" in your .proto file is just for importing other .proto's whereas the "option go_package" is what determines the package name generated into your .go files.
My question is why was this done? If you have the following in your .proto file:
syntax = "proto3";
package cool.app.v1;
option go_package = "github.com/some-user/cool-app/pkg/app/proto";
message Test{}
Then in other proto files you can reference Test using cool.app.v1.Test. But, then in the generated golang file - you end up with the following package (that last string after the last "/"):
package proto
Why wouldn't protoc just use the package specified in the .proto file? Are there other languages generated by protoc that require the same "option" override for the package name?
I'm trying to make my Go project using hexagonal architecture as described here.
In my project I'm using a gRPC communication generated with protoc from .proto file.
The directories structure:
|- grpc.proto
|-internal
|-core
|-domain
|-services
|- grpcprotocol
And my grpc.proto file has go_package option that points to a specific directory in my Go project
syntax = "proto3";
option go_package = "github.com/myuser/myrepo/internal/core/services/grpcprotocol";
...
Using protoc --go_out=internal/core/domain --go_opt=paths=source_relative --go-grpc_out=internal/core/services/grpcprotocol --go-grpc_opt=paths=source_relative ports.proto I'm able to generate both grpc.pb.go file in internal/core/domain directory and grpc_grpc.pb.go file inside internal/core/services/grpcprotocol directory.
However, grpc.pb.go has a go package named grpcprotocol while it should have a package named domain (I also use other types defined there in separate Go files).
Also grpc_grpc.pb.go file has code that uses types defined in grpc.pb.go without imports (it treats it as if it was defined in the same package).
Is it possible to split those two files into separate Go packages and enforce code that's in grpc_grpc.pb.go to import types from domain directory instead of treating them as defined in the same package?
Your best solution here is too separate the code that you want in grpcprotocol and the one you want into domain, into separate files. Such as:
domain.proto
syntax = "proto3";
package domain;
option go_package = "github.com/myuser/myrepo/internal/core/domain";
//...
grpc.proto
syntax = "proto3";
package grpcprotocol;
option go_package = "github.com/myuser/myrepo/internal/core/services/grpcprotocol";
//...
Then you could import your domain.proto in your grpc.proto, by simply writing import "domain.proto";, provide a --proto_path if domain.proto and grpc.proto are not in the same directory. And finally to reference an object from domain.proto in grpc.proto you can write:
domain.AnObject
After that you can take advantage of the --go_opt=module and --go-grpc_opt=module, to strip the module name in go_package and generate the code at the right place. Like:
protoc --go_out=. --go_opt=module=github.com/myuser/myrepo --go-grpc_out=. --go-grpc_opt=module=github.com/myuser/myrepo *.proto
What this will do is that, it will remove github.com/myuser/myrepo from each go_package and basically start from the root of your module. That's why you can do a --go_out=. and --go-grpc_out=..
Hope that helps, let me know how I can further improve my answer.
Notes
Protobuf package and go_package are not the same. The former is only used for protobuf in order to give context and it extends the qualified name. The go_package is used during go code generation.
The package in the proto file is optional, it makes things more clear and nobody can misuse you proto file without specifying the fully qualified name (little bit safer, if named properly).
I encounter an issue with Go Module management and a generation of protobuffers (using go1.16, protoc-gen-go#latest).
I have this project structure:
subproj
├── go.mod (module company.tld/proj/subproj)
├── subproj.go (entry point : package main)
├── proto (folder containing .proto files)
├── packageFolder
| └── file1.go (package packageFolder)
└── Makefile (used to generate *.pb.go and build subproj binary)
The proto folder is used by other projects (obviously...) (via git submodule).
Protos are like the following:
syntax = "proto3"
option csharp_namespace = "Proj.Proto";
option go_package = "company.tld/proj/projpb";
package entity.proj
...
because of different version of messages, few protobuffer files need to be in another "namespace":
option go_package = "company.tld/proj/projpb/other";
package entity.proj.other
In my Makefile, I tried to generate the right *.pb.go at the right place:
# Proto sources
PROTO= $(wildcard ${PROTODIR}/*.proto)
PBGO= $(PROTO:.proto=.pb.go)
MODULE_NAME=company.tld/proj
GO_OPT_FLAG= --go_opt=module=${MODULE_NAME}
GRPC_OPT_FLAG= --go-grpc_opt=module=${MODULE_NAME}
#GO_OPT_FLAG= --go_opt=paths=import
#GRPC_OPT_FLAG= --go-grpc_opt=paths=import
.PHONY: clean install proto
## Builds the project
build: proto
go build ${LDFLAGS} -o ${BINARY}
$(PROTOBUF_GO_PLUGIN):
go install google.golang.org/protobuf/cmd/protoc-gen-go#latest
$(GRPC_GO_PLUGIN):
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc#latest
%.pb.go: %.proto | $(PROTOBUF_GO_PLUGIN) $(GRPC_GO_PLUGIN)
protoc --proto_path=${PROTODIR} --go_out=. ${GO_OPT_FLAG} --go-grpc_out=. ${GRPC_OPT_FLAG} $<
proto: $(PBGO)
So, depending on the option used with the protoc compiler:
→ With --go_opt=paths=import
A folder tree company.tld/proj/projpb is created by protoc at the project's root. Each object is in a package called projpb or other, in the subpackage other.
Generated Proto objects, that include the other namespace-d objects, have the import path import other "company.tld/proj/projpb/other" (which is brought by the go_package option, but which is wrong because it is not an existing module - go mod tidy/vendor is complaining that it cannot find it).
Normal project files need the following import path to reach the Generated Proto objects :
import pb "company.tld/proj/subproj/company.tld/proj/projpb"
which seems odd and not the proper way to do.
→ With --go_opt=module=company.tld/proj
A folder projpb is created by protoc at the project's root and each generated .pb.go has the package projpb or other, in the subpackage other.
Generated Proto objects, that include the other namespace-d objects, still have the import path import other "company.tld/proj/projpb/other" (which is still brought by the go_package option and is still wrong because this is still a non-existing module - these are generated files... why would I want to create a module of these ?).
The cool thing is that with this go_opt, accessing generated types looks much more normal with
import pb "company.tld/proj/subproj/projpb".
Finally, I tried
using local import path on the go_package option in the .proto files (that is refused on build time, because there would be an import other "./projpb/other" in generated protobuffer object)
to use the replace instruction in the go.mod file like this :
replace (
company.tld/proj/projpb => ./projpb
company.tld/proj/projpb/other => ./projpb/other
)
(but go mod tidy/vendor is complaining that it cannot find the go.mod file inside the generated folder ./projpb)
Has someone encountered a similar problem? Or am I missing a command option to tell to Go, «I generate protobuffer objects in a package, or package in a package, and I simply want to use them. They are not a module, so please, provide the right import paths to the generated object and let me use them in my code».
[Update 01]
I gave a try to the go_opt=paths=source_relative (inspired by this ticket).
I created the folder in the Makefile, protoc generates files inside.
Notes:
generated protos use the full path, specified with the go_package option, to relate to one another.
As long as go_package option needs a full path, Go (go mod tidy/vendor) will want to search for a go.mod file inside the created folder, containing generated protos.
What is the correct way to tell Go that I am not looking for a Module, yet still satisfy the go_package option's full path constraint in the protobuffer file ?
After changing a numerous amount of time the go_package option in the proto files, changing the go_opt on the protoc compiler command, the only way I found to compile my project with my generated protobuffers, respecting every Go constraints, is by creating a go.mod file on-the-fly...
final proto «header» (respects the full puth in the go_package option)
syntax = "proto3";
option csharp_namespace = "Proj.Proto";
option go_package = "company.tld/proj/projpb";
// or for subpackages...
option csharp_namespace = "Proj.Proto.Other";
option go_package = "company.tld/proj/projpb/other";
my Makefile (creates a go.mod file for the generated proto files)
# Proto sources
PROTO= $(shell find ${PROTODIR} -type f -name '*.proto')
PBGO= $(PROTO:.proto=.pb.go)
DEST_DIR=.
MODULE_NAME=company.tld/proj
GO_OPT_FLAG= --go_opt=module=${MODULE_NAME}
GRPC_OPT_FLAG= --go-grpc_opt=module=${MODULE_NAME}
PROTO_PKG_DIR=projpb
PROTO_MODULE_NAME=${MODULE_NAME}/${PROTO_PKG_DIR}
PROTO_GOMOD_FILE=${PROTO_PKG_DIR}/go.mod
.PHONY: clean install proto gomod
build: proto gomod
go build ${LDFLAGS} -o ${BINARY}
%.pb.go: %.proto | $(PROTOBUF_GO_PLUGIN) $(GRPC_GO_PLUGIN) $(DEST_DIR)
${PROTOC} --proto_path=${PROTODIR} --go_out=${DEST_DIR} ${GO_OPT_FLAG} --go-grpc_out=${DEST_DIR} ${GRPC_OPT_FLAG} $<
proto: $(PBGO)
gomod: ${PROTO_GOMOD_FILE}
${PROTO_GOMOD_FILE}:
cd ${PROTO_PKG_DIR} && go mod init ${PROTO_MODULE_NAME} && cd ..
my main go.mod file (redirects the on-the-fly-created module to a local folder inside the project's scope)
module company.tld/proj/subproj
go 1.16
require (
// ...
company.tld/proj/projpb v0.0.0
)
replace company.tld/proj/projpb v0.0.0 => ./projpb
Thanks to the replace instruction, go mod tidy/vendor is happy and do not try to search the module in a remote repository.
Generated *.pb.go files have the right import path : company.tld/proj/projpb (and company.tld/proj/projpb/other for the subpackages).
And the import statement to use generated protos are working fine in the main project.
I hoped there was a simpler and more prettier solution, but alas...
Sorry for the any and thanks to those who gave it a thought !
I am fairly certain this is operator error and I am at the point I am not thinking clearly.
Here is the setup:
$GOPATH/src/github.com/<company>/<service a>/proto/a.proto
$GOPATH/src/github.com/<company>/<service b>/proto/b.proto
etc.
Now in the proto file I am using imports similar to go (perhaps the issue) such that a.proto has:
import "github.com/<company>/<service b>/b.proto"
I have possibly two separate issues.
I cannot get the import to compile properly using go:generate protoc
I cannot get the output a.pb.go file to be placed in the $GOPATH/src/github.com/<company>/<service a>/proto/ path.
I have attempted multiple configurations probably not in the correct combination.
Using option go_package = "github.com/<company>/<service b>/proto" in each .proto file
Multiple variations of go generate;
go:generate protoc --proto_path=.:$GOPATH/src --go_out=$GOPATH/src a.proto
go:generate protoc --proto_path=.:$GOPATH/src --go_out=. a.proto
go:generate protoc --go_out=import_prefix=github.com/<company>/:. api.proto
I clearly have a poor understanding on how protoc looks at import paths and file outputs. Anyone point me in the direction of what I am doing wrong?
Thanks!
Update #1
In a.proto;
option go_package = "github.com/<company>/<service a>/proto";
import "github.com/<company>/<service b>/proto/b.proto";
and the go generate;
//go:generate protoc --proto_path=$GOPATH/src --go_out=$GOPATH/src/github.com/<company>/<service a>/proto a.proto
Which is called from a go file in the proto directory with the a.proto.
I received the error;
a.proto: File does not reside within any path specified using --proto_path (or -I). You must specify a --proto_path ch encompasses this file. Note that the proto_path must be an exact prefix of the .proto file names -- protoc is too dumb to figure out when two paths (e.g. absolute and relative) are equivalent (it's harder than you think).
I have confirmed $GOPATH is to the expected location.
Solution
Thanks to Shivam Jindal for pointing me in the correct direction. The import is exactly as described in his solution. The output was a problem of my misusing both --go_out and option go_package. I used the go_package to specify the output location and --go_out to specify the root similar to --proto_path. Now everything works.
option go_package = "github.com/<company>/<service a>/proto";
and
//go:generate protoc --proto_path=$GOPATH/src/ --go_out=$GOPATH/src/ $GOPATH/src/github.com/<company>/<service a>/proto/a.proto
Thanks!
Firstly, option go_package is not meant for other dependency import at all, it's the Go package name where the new proto bindings for Go (a.pb.go file) will be placed.
Now coming to the output file location, I can see you are using go-generate. Firstly it depends from which directory you are invoking that if the path used in --go_out= is relative path. I would say use absolute paths. If you want to put the output file in that location you mentioned, use --go_out=$GOPATH/src/github.com/<company>/<service a>/proto/ in go-generate.
To correctly import the other file b.proto in your a.proto use the fully qualified import path as you have done. Just that use --proto_path $GOPATH/src in go-generate. Also please update the question with the errors you are seeing in case it does not work.
Please see this for more information on import paths.
I've got golang package github.com/user/protoapp, in this package I have folder proto containing protobuf files.
github.com/user/protoapp
|-proto
|-proto/app1
|-proto/app2
proto files in app1 and app2 have corresponing packages app1 and app;
Proto file from proto/app1 is importing file from proto/app2 like import "app2/messages.proto"; after compillation in app1.pb.go it becomes import app2 and protoapp fails to compile. How do I make imports in *.pb.go files become import "github.com/user/protoapp/proto/app2" rather than import "app2"?
you need to make your import in your proto a fully qualified path like in Go:
instead of import "app2/messages.proto";
try import "github.com/user/protoapp/proto/app2/messages.proto";
Never specify the half path "/app2/messages.proto" it won't be work.
Specify the full import name
import "github.com/user/protoapp/proto/app2/messages.proto";
and
Do define with the package name
//if we does'nt add package we define it will show error
package messagedata;