Godep

godep helps build packages reproducibly by fixing their dependencies.

This tool assumes you are working in a standard Go workspace, as described in http://golang.org/doc/code.html. We expect godep to build on Go 1.4* or newer, but you can use it on any project that works with Go 1 or newer.

Install

$ go get github.com/tools/godep

How to use godep with a new project

Assuming you've got everything working already, so you can build your project with go install and test it with go test, it's one command to start using:

$ godep save

This will save a list of dependencies to the file Godeps/Godeps.json and copy their source code into vendor/ (or Godeps/_workspace/ when using older versions of Go). Godep does not copy:

• files from source repositories that are not tracked in version control.
• *_test.go files.
• testdata directories.
• files outside of the go packages.

Godep does not process the imports of .go files with either the ignore or appengine build tags.

Test files and testdata directories can be saved by adding -t.

Read over the contents of vendor/ and make sure it looks reasonable. Then commit the Godeps/ and vendor/ directories to version control.

The deprecated -r flag

For older versions of Go, the -r flag tells save to automatically rewrite package import paths. This allows your code to refer directly to the copied dependencies in Godeps/_workspace. So, a package C that depends on package D will actually import C/Godeps/_workspace/src/D. This makes C's repo self-contained and causes go get to build C with the right version of all dependencies.

If you don't use -r, when using older version of Go, then in order to use the fixed dependencies and get reproducible builds, you must make sure that every time you run a Go-related command, you wrap it in one of these two ways:

• If the command you are running is just go, run it as godep go ..., e.g. godep go install -v ./...
• When using a different command, set your $GOPATH using godep path as described below.

-r isn't necessary with go1.6+ and isn't allowed.

Additional Operations

Restore

The godep restore command is the opposite of godep save. It will install the package versions specified in Godeps/Godeps.json to your $GOPATH. This modifies the state of packages in your $GOPATH.

Edit-test Cycle

1. Edit code
2. Run godep go test
3. (repeat)

Add a Dependency

To add a new package foo/bar, do this:

1. Run go get foo/bar
2. Edit your code to import foo/bar.
3. Run godep save (or godep save ./...).

Update a Dependency

To update a package from your $GOPATH, do this:

1. Run go get -u foo/bar
2. Run godep update foo/bar. (You can use the ... wildcard, for example godep update foo/...).

Before comitting the change, you'll probably want to inspect the changes to Godeps, for example with git diff, and make sure it looks reasonable.

Multiple Packages

If your repository has more than one package, you're probably accustomed to running commands like go test ./..., go install ./..., and go fmt ./.... Similarly, you should run godep save ./... to capture the dependencies of all packages in your application.

File Format

Godeps is a json file with the following structure:

type Godeps struct {
	ImportPath string
	GoVersion  string   // Abridged output of 'go version'.
	Packages   []string // Arguments to godep save, if any.
	Deps       []struct {
		ImportPath string
		Comment    string // Description of commit, if present.
		Rev        string // VCS-specific commit ID.
	}
}

Example Godeps:

{
	"ImportPath": "github.com/kr/hk",
	"GoVersion": "go1.6",
	"Deps": [
		{
			"ImportPath": "code.google.com/p/go-netrc/netrc",
			"Rev": "28676070ab99"
		},
		{
			"ImportPath": "github.com/kr/binarydist",
			"Rev": "3380ade90f8b0dfa3e363fd7d7e941fa857d0d13"
		}
	]
}

Migrating to vendor/

Godep supports the Go 1.5+ vendor/ experiment utilizing the same environment variable that the go tooling itself supports (GO15VENDOREXPERIMENT).

godep mostly works the same way as the go command line tool. If you have go 1.5.X and set GO15VENDOREXPERIMENT=1 or have go1.6.X (or devel) vendor/ is enabled. Unless you already have a Godeps/_workspace. This is a safety feature and godep warns you about this.

When vendor/ is enabled godep will write the vendored code into the top level ./vendor/ directory. A ./Godeps/Godeps.json file is created to track the dependencies and revisions. vendor/ is not compatible with rewrites.

There is currently no automated migration between the old Godeps workspace and the vendor directory, but the following steps should work:

# just to be safe
$ unset GO15VENDOREXPERIMENT

# restore currently vendored deps to the $GOPATH
$ godep restore

# The next line is only needed to automatically undo rewritten imports that were
# created with godep save -r.
$ godep save -r=false <pkg spec>

# Remove the old Godeps folder
$ rm -rf Godeps

# If on go1.5.X to enable `vendor/`
$ export GO15VENDOREXPERIMENT=1

# re-analyze deps and save to `vendor/`. 
$ godep save <pkg spec>

# Add the changes to your VCS
$ git add -A . ; git commit -am "Godep workspace -> vendor/"

# You should see your Godeps/_workspace/src files "moved" to vendor/.

Releasing

1. Increment the version in version.go.
2. Tag the commit with the same version number.
3. Update Changelog.md.