If I'm following this correctly, your core problem is that protoc doesn't
understand vendored paths as used by the go tool. For example:

- You have a proto file located in src/square/up/protos/square.proto.
- square.proto imports "
github.com/golang/protobuf/ptypes/timestamp/timestamp.proto".
- timestamp.proto is actually located in "src/square/up/vendor/
github.com/.../timestamp.proto".

You can't run "protoc --go_out=. square/up/protos/square.proto", because
protoc won't be able to locate the vendored copy of timestamp.proto. If it
did, everything would work correctly without setting an import_prefix.

It would be nice for Go users if protoc did understand vendored paths.
Failing that, however, I think you can get what you want with a very small
wrapper around protoc. The wrapper can copy a proto and all its
dependencies into a temp directory (pulling dependencies from vendored
paths as necessary), run protoc there, and copy the result back. e.g., in
the case of the above example:

$ mkdir -p /tmp/x/square/up/protos
$ cp src/square/up/protos/square.proto /tmp/x/square/up/protos
$ mkdir -p /tmp/x/github.com/golang/protobuf/ptypes/timestamp
$ cp square/up/vendor/
github.com/golang/protobuf/ptypes/timestamp/timestamp.proto
github.com/golang/protobuf/ptypes/timestamp
$ cd /tmp/x && protoc -go_out=. square/up/protos/square.proto
$ cp /tmp/x/square/up/protos/square.pb.go square/up/protos

The generated .go files will reference non-vendored paths, which the Go
compiler will resolve to the correct vendored directory.

Does that seem like it would work for you?

On Sun, Jul 10, 2016 at 12:32 PM, Zellyn Hunter <zel...@gmail.com> wrote:

> Usually not too tricky. The problem is that protos and most other
> programming languages prohibit circular imports at the file level, and Go
> does it at the package level. The fact that protoc and the other languages
> are okay with a topology ensures there is a valid Go repackaging that will
> work.
>
> Zellyn
>
> On Fri, Jul 8, 2016, 6:52 PM 'Josh Haberman' via Protocol Buffers <
> protobuf@googlegroups.com> wrote:
>
>> I don't know the background of the Go import system or go_package option.
>> However this statement concerns me a little:
>>
>> > We have to use go_package to reorganize things that are fine in
>> Java/Ruby, but would be circular package imports in Go.
>>
>> Is this implying that certain .proto files would generate invalid Go code
>> until you manually insert some go_package statements? How tricky is it to
>> do this manual untangling?
>>
>>
>> On Friday, July 1, 2016 at 7:53:03 PM UTC-7, Zellyn wrote:
>>>
>>> Oh wow. Thanks for thinking about it so carefully!
>>>
>>> I should mention: before you could actually specify full package paths
>>> to the Go proto plugin, earlier versions of our wrapper (
>>> https://github.com/square/goprotowrap) just forcibly manhandled things
>>> into the shape we wanted by explicitly specifying -M parameter import
>>> rewrites for *every single* import, and renaming the output files into
>>> place.
>>>
>>> So it's definitely possible to shape things as you want. However, I
>>> would prefer to find a solution that works with the official plugin,
>>> because I don't believe our setup is remarkable or unusual: as GRPC sees an
>>> increase in use as a cross-language RPC mechanism, everyone else is going
>>> to struggle with the same things.
>>>
>>> Zellyn
>>>
>>> On Fri, Jul 1, 2016 at 7:32 PM Ross Light <li...@google.com> wrote:
>>>
>>>> Sorry for the delayed response!  I've written about 3-4 draft replies
>>>> over this week that I've discarded because they don't meet your
>>>> requirements.  I'll think about it more over the long weekend and get back
>>>> to you.
>>>>
>>>> Cheers,
>>>> -Ross
>>>>
>>>>
>>>> On Fri, Jul 1, 2016 at 3:11 PM Jie Luo <jie...@google.com> wrote:
>>>>
>>>>> +Ross who is working on Go protobuf.
>>>>>
>>>>> Ross, do you have any comments or suggestions?
>>>>>
>>>>> On Fri, Jun 24, 2016 at 8:35 AM, Zellyn <zel...@gmail.com> wrote:
>>>>>
>>>>>> Hi folks,
>>>>>>
>>>>>> Apologies in advance for the complex email. It takes a bit of
>>>>>> explaining to set up what we're having trouble with.
>>>>>>
>>>>>> I would like to lay out how we generate protos in Go (using our
>>>>>> unfortunately forked version of the protoc plugin), and ask for 
>>>>>> suggestions
>>>>>> as to how to accomplish the same thing with the unforked version. In the
>>>>>> process, I wish to ask questions about the post-vendor-experiment utility
>>>>>> of the current behavior of import_prefix, hopefully generating more
>>>>>> discussion than I managed to here
>>>>>> <https://github.com/golang/protobuf/issues/181>.
>>>>>>
>>>>>> Background:
>>>>>>
>>>>>>    - We have protos spread around all over the place: in our Go
>>>>>>    monorepo, in our Java monorepo, and in miscellaneous Ruby repos.
>>>>>>    - We collect them all into a single directory before generating
>>>>>>    Go code. Call it $COLLECT_DIR
>>>>>>    - We have to use go_package to reorganize things that are fine in
>>>>>>    Java/Ruby, but would be circular package imports in Go.
>>>>>>    - For historical reasons, our Go repo is checked out to
>>>>>>    $GOPATH/src/square/up. I know it's a little weird, but it's logically
>>>>>>    equivalent to any other location. Pretend "square/up" is "square3" if 
>>>>>> you
>>>>>>    likeā€¦ :-)
>>>>>>    - Our monorepo's vendor folder lives at
>>>>>>    $GOPATH/src/square/up/vendor/...
>>>>>>    - We want to generate protos into $GOPATH/src/square/up/protos to
>>>>>>    keep them all in one place.
>>>>>>    - Most of our protos are in package "squareup.*", but we have
>>>>>>    some third-party protos that have their own packages. Or none (eg.
>>>>>>    nanopb
>>>>>>    <https://github.com/PIlin/nanopb/blob/master/generator/nanopb.proto>
>>>>>>    ).
>>>>>>    - Right now we also have copies of WKT protos in $COLLECT_DIR,
>>>>>>    but I'd love to just import them from their vendor folder locations.
>>>>>>
>>>>>> *What we do now: f**ull go_package including "protos" folder in
>>>>>> protobufs*
>>>>>>
>>>>>> Add full package and path go_package to every protobuf:
>>>>>> eg. For a file with package "squareup.testing", we set option
>>>>>> go_package = "square/up/squareup/protos/testing".
>>>>>> (We haven't actually added these declarations everywhere yet: this is
>>>>>> what our forked plugin does: if go_package doesn't specify package path, 
>>>>>> we
>>>>>> use square/up/protos + slash-separated-package. But it's about the same
>>>>>> thing. Our fork was created long before go_package gained the ability to
>>>>>> actually specify output package path)
>>>>>>
>>>>>> Cons:
>>>>>>
>>>>>>    - We generate into the output directory of $GOPATH/src, which is
>>>>>>    terrible: we could accidentally generate stuff into any arbitrary go
>>>>>>    package in our GOPATH. :-(
>>>>>>    - We're writing an implementation detail (where we currently
>>>>>>    store protos) into all the proto files
>>>>>>
>>>>>> *What I would like to do:*
>>>>>>
>>>>>> Generate into an output directory of $GOPATH/src/square/up/protos,
>>>>>> and use the import_prefix option to ensure that things get imported from
>>>>>> the right place.
>>>>>>
>>>>>> *Why that doesn't work:*
>>>>>>
>>>>>>    - import_prefix is added to *every* import, including grpc
>>>>>>    packages, the context package, the proto runtime package, etc. This 
>>>>>> made
>>>>>>    sense when the prefix was intended to be something like
>>>>>>    "square/up/Godep/_workspace/" (eg. vendoring by 
>>>>>> import-path-rewriting), but
>>>>>>    doesn't make sense anymore.
>>>>>>    - import_prefix is added to imports for ALL protos, including
>>>>>>    things like well-known-type protos that should just live under
>>>>>>    $GOPATH/src/square/up/vendor/github.com/golang/protobuf/proto
>>>>>>
>>>>>> *What I'd like to get out of this:*
>>>>>> Either:
>>>>>>
>>>>>>    - a reworking of the way import_prefix works
>>>>>>    - a new parameter with slightly different semantics: adds an
>>>>>>    import prefix only for protos, and only for protos in a particular 
>>>>>> list of
>>>>>>    folders:
>>>>>>       - eg. proto_import_prefix_by_dir=$COLLECT_DIR:square/up/protos
>>>>>>    - an explanation of how I'm Doing it Wrong - I'm happy to change
>>>>>>    things. While there's a lot of existing code, Go protos have caused 
>>>>>> me so
>>>>>>    much pain, I'm willing to invest pretty significant effort.
>>>>>>
>>>>>> *Why I'd like to defork*
>>>>>>
>>>>>> Our fork was created before go_package could rearrange output
>>>>>> packages (commit
>>>>>> <https://github.com/golang/protobuf/commit/c75fbf01dc6cb73649c4cd4326182c3e44aa9dbb>).
>>>>>> With the recent increase in grpc-related volatility of the protobuf
>>>>>> package, it's increasingly painful to maintain our fork. And since grpc
>>>>>> updates are often tied to proto updates, I can't simply avoid updating 
>>>>>> it.
>>>>>> Plus all the usual reasons maintaining a fork is terrible :-)
>>>>>>
>>>>>> Comments, suggestions, and help welcome.
>>>>>>
>>>>>> Zellyn
>>>>>>
>>>>>> cc dsymonds, matloob at Google, Josh at Square.
>>>>>>
>>>>>> --
>>>>>> You received this message because you are subscribed to the Google
>>>>>> Groups "Protocol Buffers" group.
>>>>>> To unsubscribe from this group and stop receiving emails from it,
>>>>>> send an email to protobuf+unsubscr...@googlegroups.com.
>>>>>> To post to this group, send email to protobuf@googlegroups.com.
>>>>>> Visit this group at https://groups.google.com/group/protobuf.
>>>>>> For more options, visit https://groups.google.com/d/optout.
>>>>>>
>>>>>
>>>>> --
>> You received this message because you are subscribed to a topic in the
>> Google Groups "Protocol Buffers" group.
>> To unsubscribe from this topic, visit
>> https://groups.google.com/d/topic/protobuf/W2zN-xKsdgk/unsubscribe.
>> To unsubscribe from this group and all its topics, send an email to
>> protobuf+unsubscr...@googlegroups.com.
>> To post to this group, send email to protobuf@googlegroups.com.
>> Visit this group at https://groups.google.com/group/protobuf.
>> For more options, visit https://groups.google.com/d/optout.
>>
>

-- 
You received this message because you are subscribed to the Google Groups 
"Protocol Buffers" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to protobuf+unsubscr...@googlegroups.com.
To post to this group, send email to protobuf@googlegroups.com.
Visit this group at https://groups.google.com/group/protobuf.
For more options, visit https://groups.google.com/d/optout.

Reply via email to