Respect go_prefix attr of dependencies

[yugui]

Uses go_prefix attr of individual dependencies to calculate their
importpaths. This allows users to use Bazel's external dependency
resolution -- {,new_}git_repository rules -- to manage Go libraries.

c.f. #16 (comment)

Supports case 1 and 3 in #16.

[bazel-io]

Can one of the admins verify this patch?

[yugui]

Jenkins: test this please.

[yugui]

Hmm, "test this please" does not work.
Does it mean I need to be a member of bazel organization but not just a collaborator of rules_go to trigger CI?

[damienmg]

Yes, you need to be member of bazelbuild and make it public (https://github.com/orgs/bazelbuild/people/yugui)

Jenkins test this please.

[damienmg]

This seems like a pretty easy way to do a go_vendor macro rule:

TEMPLATE = """
load("@io_bazel_rules_go//go:def.bzl", "go_prefix", "go_library")

go_prefix("github.com/%s/%s")

go_library(name = "go_default_library", srcs = glob(["**/*.go"]), visibility = ["//visibility:public"])
"""

def go_vendor(org, project, commit):
  new_git_repository(name = "com_github_%s_%s" % (org, project), remote = "https://github.com/%s/%s.git" % (org, project), commit = commit, build_file_content = TEMPLATE % (org, project))

[damienmg]

Actually io_bazel_rules_go won't work currently. You have to use a trick with str(Label(...)) for now.

[yugui]

@damienmg
I would like to keep go_vendor separated from this PR because other go libraries requires much more work. It it acceptable for you?

The simple macro works fine with glog but other common go libraries are more complex. e.g. https://github.com/golang/oauth2 requires:

• parsing build tags
• dependency analysis in the repository
• external dependency

[damienmg]

Yes sounds reasonable.

I don't think you need to handle all the cases for an initial version but sure you might want to handle some more than a basic build.

[yugui]

@damienmg
The URL https://github.com/orgs/bazelbuild/people/yugui is invalid because I'm not a member of bazel organization.
Could you add me to the organization again?

[damienmg]

LGTM

[damienmg]

For the org: you have a pending invitation, you should be able to accept it.

[yugui]

I found the invitation mail in my inbox. Thank you!