Use canonical import path if present about heroku-buildpack-go

[freeformz]

@kr I would assume that godep (or similar tooling) would DTRT when vendoring here instead of pushing this down to the build pack.

[kr]

Yes, godep should do the right thing. But this issue also has to do with projects that don't use godep. It used to be that, for such projects, the buildpack had no way to know the import path (which is why we defined the .godir convention). Now, the buildpack can check for a canonical import path magic comment.

Of the three possible ways to figure out the app's import path (Godeps.json, .godir, canonical import path), the canonical import path is the only one defined and approved by the Go team and used by stock go tooling that ships with the compiler. So I think if the canonical import path is present, it should be used.

[cyx]

Do you mean defining GOPATH as an environment variable and having the
buildpack read that?

On Sun, May 17, 2015 at 12:40 PM, Keith Rarick [email protected]
wrote:

Yes, godep should do the right thing. But this issue also has to do with
projects that don't use godep. It used to be that, for such projects, the
buildpack had no way to know the import path (which is why we defined the
.godir convention). Now, the buildpack can check for a canonical import
path magic comment.

Of the three possible ways to figure out the app's import path (
Godeps.json, .godir, canonical import path), the canonical import path is
the only one defined and approved by the Go team and used by stock go
tooling that ships with the compiler. So I think if the canonical import
path is present, it should be used.

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[kr]

Do you mean defining GOPATH as an environment variable and having the
buildpack read that?

No, please see the link above for the definition of a canonical import path. This is about determining the base import path for the app. It is orthogonal to the choice of GOPATH.

[freeformz]

@kr My plan (pending some discussion and fact finding) is to remove support for non godep deploys, possibly adding in support for tools like https://github.com/kardianos/vendor and https://github.com/constabulary/gb as they become more feature complete.

[elithrar]

@freeformz Before I consider hacking on anything, have you started any work on making gb build (and/or also gb-vendor) an option for the buildpack?

[freeformz]

@elithrar Not as of yet as we've been focused on prepping some other stuff.

I'm happy to review your work when it's ready!

[kr]

Some more facts for your finding: this thread was revived today. https://groups.google.com/d/msg/golang-dev/74zjMON9glU/4lWCRDCRZg0J

If we're lucky, all the vendoring tools (and users thereof) will converge on this convention, and the buildpack will have only to run go install -vendor ./... and care not which vendoring tool was used. 😁

(Of course, that doesn't solve the issue of how to find the import path of the repo root, but this issue provides a pretty clear way to handle that: canonical import paths.)

[elithrar]

Yep, that's what prompted me to comment here! I'm thinking (with Go 1.5 in
mind) of the following changes:

• When Go 1.5 hits we test for the presence of a /vendor directory in the
  build dir and (if so) run go install -vendor ./... - should be able to
  drop it in ahead of the godeps checks in
  https://github.com/heroku/heroku-buildpack-go/blob/master/bin/compile#L58
  and other areas where we check for godeps today.
• Else we continue to either run godep or go get (if .godir exists) as
  per the present

That way, if a user is using (for example) gb-vendor it doesn't matter:
that's something for them to manage at a repo level. Heroku just accepts
the push and the buildpack detects the appropriate action. Since the
buildpack hardcodes the Go version there shouldn't be a need to do a
version check to determine if go build -vendor is safe either.

On Fri, Jun 12, 2015 at 12:44 PM Keith Rarick [email protected]
wrote:

Some more facts for your finding: this thread was revived today.
https://groups.google.com/d/msg/golang-dev/74zjMON9glU/4lWCRDCRZg0J

If we're lucky, all the vendoring tools (and users thereof) will converge
on this convention, and the buildpack will have only to run go install
-vendor ./... and care not which vendoring tool was used. [image: 😁]

(Of course, that doesn't solve the issue of how to find the import path of
the repo root, but this issue provides a pretty clear way to handle that:
canonical import paths.)

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[kr]

In the spirit of being a little more on-topic, here is how to get the canonical import path, aka "import comment":

go list -f {{.ImportComment}}

[freeformz]

Please see #83. I haven't tested it yet.
/cc @cyx

[cyx]

Cool, will check in a few.

On Tue, Jun 16, 2015 at 11:33 AM, Edward Muller [email protected]
wrote:

Please see #83 #83. I
haven't tested it yet.
/cc @cyx https://github.com/cyx

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[freeformz]

Closing this in favor of #88