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Organizing Go Projects and Dependencies

21 Mar 2014

Go is build around the concept of a GOPATH which is a common workspace for most (or all) of your Go source code. This works well but sometimes you don't want the third party packages you depend on to be in your primary GOPATH. I can think of a few reasons for this:

I looked at many Go projects to find a solution I liked. There are a lot of approaches to this problem including many attempts at a package manager for Go. The community is very much in flux around this topic.

Personally, I felt any package manager tool was overkill for my needs. I was also discouraged by the fact that the community hasn't rallied behind any single package management solution.

In the end, this is my recipe for Go application structure.

Solution:

For context, my system GOPATH is ~/mygo.

My project is at ~/mygo/src/bitbucket.org/USERNAME/PROJECT.

~/mygo/src/bitbucket.org/USERNAME/PROJECT
|-- .gitignore
|-- README
|-- Makefile
|-- _vendor # Third party packages. This is a typical GOPATH workspace.
|   `-- src
|       `-- github.com
|           |-- codegangsta
|           |   |-- inject
|           |   `-- martini
|           `-- jpoehls
|               `-- gophermail
|-- bin  # My app's binary output.
|-- docs # My app's documentation.
`-- src  # My app's source code.
    |-- main_app
    |-- some_pkg
    `-- some_other_pkg

My Makefile looks like this:

.PHONY: build doc fmt lint run test vendor_clean vendor_get vendor_update vet

# Prepend our _vendor directory to the system GOPATH
# so that import path resolution will prioritize
# our third party snapshots.
GOPATH := ${PWD}/_vendor:${GOPATH}
export GOPATH

default: build

build: vet
	go build -v -o ./bin/main_app ./src/main_app

doc:
	godoc -http=:6060 -index

# http://golang.org/cmd/go/#hdr-Run_gofmt_on_package_sources
fmt:
	go fmt ./src/...

# https://github.com/golang/lint
# go get github.com/golang/lint/golint
lint:
	golint ./src

run: build
	./bin/main_app

test:
	go test ./src/...

vendor_clean:
	rm -dRf ./_vendor/src

# We have to set GOPATH to just the _vendor
# directory to ensure that `go get` doesn't
# update packages in our primary GOPATH instead.
# This will happen if you already have the package
# installed in GOPATH since `go get` will use
# that existing location as the destination.
vendor_get: vendor_clean
	GOPATH=${PWD}/_vendor go get -d -u -v \
	github.com/jpoehls/gophermail \
	github.com/codegangsta/martini

vendor_update: vendor_get
	rm -rf `find ./_vendor/src -type d -name .git` \
	&& rm -rf `find ./_vendor/src -type d -name .hg` \
	&& rm -rf `find ./_vendor/src -type d -name .bzr` \
	&& rm -rf `find ./_vendor/src -type d -name .svn`

# http://godoc.org/code.google.com/p/go.tools/cmd/vet
# go get code.google.com/p/go.tools/cmd/vet
vet:
	go vet ./src/...

Notes:

How do you structure your Go projects? What does your build script look like? I'm always interested in improving my methods, let me know what's working for you!

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