Using subpackages with go mod locally

go dependency-management go-modules
atp picture atp · Nov 18, 2018 · Viewed 7.4k times · Source

I have a go package located on my filesystem (not in the $GOPATH), called bitbucket.org/me/awesome. 

~/awesome> tree
.
├── main.go
├── go.mod
├── go.sum
├── subpackageA
│   └── main.go

My go.mod looks like:

module bitbucket.org/me/awesome

require (
       ... # lots of external dependencies
)

replace bitbucket.org/me/awesome => ./

In main.go in my top-level directory, I call a subpackage like follows:

import "bitbucket.org/me/awesome/subpackageA"

which all seems pretty normal. go get works. However, when I clone this entire repository somewhere else (say in a Docker image) and run go get for the first time, I get errors like:

package bitbucket.org/me/awesome/subpackageA: https://api.bitbucket.org/2.0/repositories/me/awesome?fields=scm: 403 Forbidden,

which means it's not using the local filesystem version of the packages, even though I told it to with the replace directive in the go.mod file.

What am I doing wrong? How do I ensure that subpackages are used from the filesystem instead of attempting to be fetched from the internet?

Answer

Volker picture Volker · Nov 19, 2018

Go has no (real) notion of "subpackage". All packages are basically treated equal. This means that a replace bitbucket.org/me/awesome does not influence package bitbucket.org/me/awesome/subpackageA as these are two individual, unrelated packages. The folder layout does not introduce a relation of subpackageA to awsome, or the other way around *).

So you need to add an individual replace directive for subpackageA

replace bitbucket.org/me/awesome/subpackageA => ./subpackageA

*) Nitpicking for absolute correctness: Folder layout does have influence for folders named internal (cannot be imported from other projects), for folders named vendor (which may contain vendored packages) and searching for a go.mod file stops at the repo root.

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