proto_library build rules

[davidzchen]

The Build Encyclopedia documentation for objc_proto_library references proto_library, which does not seem to have been open sourced yet.

On the same note, objc_proto_library seems to be the only available rule for building proto libraries. What is the plan for proto_library rules for other languages?

[laszlocsomor]

We're not yet ready to open-source the more generic proto_library rule. In the meantime you can use genproto, see https://github.com/google/bazel/blob/master/src/main/protobuf/BUILD, or write a genrule.
I'll remove the reference from the BE for now.

[laszlocsomor]

(sorry, shouldn't have closed this just yet)

[collinw]

Is there a timeline for releasing proto_library support? We'd love to ditch Kythe's campfire build system, but can't feasibly do so without proto_library.

[damienmg]

For now we have a genproto that supports Java using Skylark (see
tools/build_rules/genproto.bzl and its usage in the link Laszlo sent. You
can easily adapt it for other languages.

On Fri, Apr 3, 2015 at 1:57 AM Collin Winter notifications@github.com
wrote:

Is there a timeline for releasing proto_library support? We'd love to
ditch Kythe's campfire build system, but can't feasibly do so without
proto_library.

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#52 (comment).

[schroederc]

The Kythe team has found that the genproto rule isn't as easy to use as you've suggested. It seems to have at least one severe issue that we'd need fixed before we migrate to using Bazel.

Bazel special-cases the genproto Skylark rule for Java (see BazelJavaRuleClasses.java). It does not, however, support the native C++ rules in the same way. We have thought of a few ways to workaround this problem but feel that they would burden us in the same way as having our own build system. Switching to Bazel (from Campfire) is meant to remove these types of concerns from our team.

Likewise, having to write our own support for C++ (and Go) means maintaining even more build-related logic. It would be nice if C++ was supported in genproto by the Bazel team. That would minimize our need for forking/maintaining the existing rule.

Other Relevant C++ issues:

• Can't depend on non-cc_library libraries in libs #114
• Unclear or impossible to return new includes from a custom rule #117

[ulfbot]

You should be able to write a genproto rule that generate .c or .cc files
and put that into cc_library.srcs. If you want to make it look like what we
have internally, you can wrap that in a Skylark macro.

We're working on proto_library as well as go support this quarter. It's
unlikely that we'll explicitly support something else before that is ready.
If we were in a hurry, go support could be ready in ~weeks, but proper
proto_library support is tricky.

On Mon, Apr 13, 2015 at 7:06 PM, Cody Schroeder notifications@github.com
wrote:

The Kythe team has found that the genproto rule isn't as easy to use as
you've suggested. It seems to have at least one severe issue that we'd need
fixed before we migrate to using Bazel.

Bazel special-cases the genproto Skylark rule for Java (see
BazelJavaRuleClasses.java
https://github.com/google/bazel/blob/master/src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java#L118).
It does not, however, support the native C++ rules in the same way. We have
thought of a few ways to workaround this problem but feel that they would
burden us in the same way as having our own build system. Switching to
Bazel (from Campfire) is meant to remove these types of concerns from our
team.

Likewise, having to write our own support for C++ (and Go) means
maintaining even more build-related logic. It would be nice if C++ was
supported in genproto by the Bazel team. That would minimize our need for
forking/maintaining the existing rule.

Other Relevant C++ issues:

• Can't depend on non-cc_library libraries in libs #114 Can't depend on non-cc_library libraries in libs #114
• Unclear or impossible to return new includes from a custom rule #117 Unclear or impossible to return new includes from a custom rule #117

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#52 (comment).

[mzhaom]

I have a simple macro that creates genrule and cc_library targets for proto files, just FYI:
https://github.com/mzhaom/trunk/blob/master/third_party/grpc/grpc_proto.bzl

[damienmg]

A quick status update: this is something we working on shiping but it will take a long time

[clconway]

Any ETA on this? We're using protos in Shipshape and would love to use standard rules.

[damienmg]

Not yet. We are thinking of shipping it by the end of the year but it is
not yet decided. You are pinging at the good moment :)

On Tue, Oct 6, 2015, 1:53 AM clconway notifications@github.com wrote:

Any ETA on this? We're using protos in Shipshape
https://github.com/google/shipshape/blob/master/shipshape/proto and
would love to use standard rules.

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#52 (comment).

[damienmg]

It should happens this quarter

[perezd]

Will this support Go when it ships?

[damienmg]

Yes. It will support both Skylark and native rules.

[arslan-urtashev]

Hi! Is there any status update? Thanks

[damienmg]

I think we are moving to making the rules provided by google/protobuf good one instead of shipping our legacy support. No ETA.

[kqyang]

Any status update on this?

[robfig]

What is the current guidance for generating Java from proto files?

[pcj]

@robfig I just released https://github.com/pubref/rules_protobuf/tree/0.1.1 for my own use but hopefully it's useful for you.

[jcanizales]

@pcj I love your graphical explanation of that repo :D

[smr277]

It seems that proto_library now exists here: http://bazel.io/docs/be/protocol-buffer.html
However, it a) needs the protobuf library to be in third_party/protobuf, and I can't seem to get it working with cc_library. Has anyone used the builtin proto_library with c++?

[pcj]

@smr277 It's probably still premature for native proto_library. However, I've done fair amount of work on https://github.com/pubref/rules_protobuf since last comment. Supports C++ protobufs with gRPC and SSL out of the box.

[ejona86]

@smr277, proto_library doesn't generate for each language at this point. There will need to be per-language support for protobuf, and that is still in the works.

[cgrushko]

Some form of status update is in
bazel-contrib/rules_go#121 (comment)

[lukaszx0]

@cgrushko you mentioned in an issue for grpc-java that there's a first class support for java_proto_library but I don't see docs for it. Is it just undocumented yet?

[lukaszx0]

Oh, they're under java, and I was looking under protocol buffer.

My bad. Please ignore me! Sorry for the noise.

[cgrushko]

(didn't know it got undocumented; I thought that only happens at the next release)
I put together a demo repo in https://github.com/cgrushko/proto_library,
and I'm working on a blog post (or at least a Gist).

[lukaszx0]

@cgrushko nice, thanks!

[cgrushko]

Blog post: https://bazel.build/blog/index.html#protocol-buffers-in-bazel

I'll close this issue because it seems to have grown to include too many things; if your issue hasn't been addressed, please open a new issue and CC me.

[ejona86]

For posterity, https://bazel.build/blog/2017/02/27/protocol-buffers.html is the permalink to the blog post.

[renning22]

I failed to compile Bazel from head by Bazel. When will this feature be distributed?

[cgrushko]

Next bazel release. There should be an issue open for it.