Dep

dep is a prototype dependency management tool for Go. It requires Go 1.7 or newer to compile.

dep is the official experiment, but not yet the official tool. Check out the Roadmap for more on what this means!

Current status

dep is safe for production use. That means two things:

Any valid metadata file (Gopkg.toml and Gopkg.lock) will be readable and considered valid by any future version of dep.
The CLI UI is mostly stable. dep init and dep ensure are mostly set; dep status is likely to change a fair bit, and dep prune is going to be absorbed into dep ensure.
Generally speaking, it has comparable or fewer bugs than other tools out there.

That said, keep in mind the following:

dep is still changing rapidly. If you need stability (e.g. for CI), it's best to rely on a released version, not tip.
dep's exported API interface will continue to change in unpredictable, backwards-incompatible ways until we tag a v1.0.0 release.

Context

Setup

Get the tool via

$ go get -u github.com/golang/dep/cmd/dep

On macOS you can install or upgrade to the latest released version with Homebrew:

$ brew install dep
$ brew upgrade dep

To start managing dependencies using dep, run the following from your project's root directory:

$ dep init

This does the following:

Look for existing dependency management files to convert
Check if your dependencies use dep
Identify your dependencies
Back up your existing vendor/ directory (if you have one) to _vendor-TIMESTAMP/
Pick the highest compatible version for each dependency
Generate Gopkg.toml ("manifest") and Gopkg.lock files
Install the dependencies in vendor/

Usage

There is one main subcommand you will use: dep ensure. ensure first checks that Gopkg.lock is consistent with Gopkg.toml and the imports in your code. If any changes are detected, dep's solver works out a new Gopkg.lock. Then, dep checks if the contents of vendor/ are what Gopkg.lock (the new one if applicable, else the existing one) says it should be, and rewrites vendor/ as needed to bring it into line.

In essence, dep ensure works in two phases to keep four buckets of state in sync:

Note: until we ship vendor verification, we can't efficiently perform the Gopkg.lock <-> vendor/ comparison, so dep ensure unconditionally regenerates all of vendor/ to be safe.

dep ensure is safe to run early and often. See the help text for more detailed usage instructions.

$ dep help ensure

Installing dependencies

(if your vendor/ directory isn't checked in with your code)

$ dep ensure

If a dependency already exists in your vendor/ folder, dep will ensure it matches the constraints from the manifest. If the dependency is missing from vendor/, the latest version allowed by your manifest will be installed.

Adding a dependency

$ dep ensure -add github.com/foo/bar

This adds a version constraint to your Gopkg.toml, and updates Gopkg.lock and vendor/. Now, import and use the package in your code!

dep ensure -add has some subtle behavior variations depending on the project or package named, and the state of your tree. See dep ensure -examples for more information.

Changing dependencies

If you want to:

Change the allowed version/branch/revision
Switch to using a fork

for one or more dependencies, do the following:

Manually edit your Gopkg.toml.
Run
```
$ dep ensure
```

Checking the status of dependencies

Run dep status to see the current status of all your dependencies.

$ dep status
PROJECT                             CONSTRAINT     VERSION        REVISION  LATEST
github.com/Masterminds/semver       branch 2.x     branch 2.x     139cc09   c2e7f6c
github.com/Masterminds/vcs          ^1.11.0        v1.11.1        3084677   3084677
github.com/armon/go-radix           *              branch master  4239b77   4239b77

On top of that, if you have added new imports to your project or modified Gopkg.toml without running dep ensure again, dep status will tell you there is a mismatch between Gopkg.lock and the current status of the project.

$ dep status
Lock inputs-digest mismatch due to the following packages missing from the lock:

PROJECT                         MISSING PACKAGES
github.com/Masterminds/goutils  [github.com/Masterminds/goutils]

This happens when a new import is added. Run `dep ensure` to install the missing packages.

As dep status suggests, run dep ensure to update your lockfile. Then run dep status again, and the lock mismatch should go away.

Updating dependencies

Updating brings the version of a dependency in Gopkg.lock and vendor/ to the latest version allowed by the constraints in Gopkg.toml.

You can update just a targeted subset of dependencies (recommended):

$ dep ensure -update github.com/some/project github.com/other/project
$ dep ensure -update github.com/another/project

Or you can update all your dependencies at once:

$ dep ensure -update

"Latest" means different things depending on the type of constraint in use. If you're depending on a branch, dep will update to the latest tip of that branch. If you're depending on a version using a semver range, it will update to the latest version in that range.

Removing dependencies

Remove the imports and all usage from your code.
Remove [[constraint]] rules from Gopkg.toml (if any).
Run
```
$ dep ensure
```

Testing changes to a dependency

Making changes in your vendor/ directory directly is not recommended, as dep will overwrite any changes. Instead:

Delete the dependency from the vendor/ directory.
```
rm -rf vendor/<dependency>
```
Add that dependency to your GOPATH, if it isn't already.
```
$ go get <dependency>
```
Modify the dependency in $GOPATH/src/<dependency>.
Test, build, etc.

Don't run dep ensure until you're done. dep ensure will reinstall the dependency into vendor/ based on your manifest, as if you were installing from scratch.

This solution works for short-term use, but for something long-term, take a look at virtualgo.

To test out code that has been pushed as a new version, or to a branch or fork, see changing dependencies.

Semantic Versioning

dep ensure a uses an external semver library to interpret the version constraints you specify in the manifest. The comparison operators are:

=: equal
!=: not equal
>: greater than
<: less than
>=: greater than or equal to
<=: less than or equal to
-: literal range. Eg: 1.2 - 1.4.5 is equivalent to >= 1.2, <= 1.4.5
~: minor range. Eg: ~1.2.3 is equivalent to >= 1.2.3, < 1.3.0
^: major range. Eg: ^1.2.3 is equivalent to >= 1.2.3, < 2.0.0
[xX*]: wildcard. Eg: 1.2.x is equivalent to >= 1.2.0, < 1.3.0

You might, for example, include a constraint in your manifest that specifies version = "=2.0.0" to pin a dependency to version 2.0.0, or constrain to minor releases with: version = "2.*". Refer to the semver library documentation for more info.

Note: When you specify a version without an operator, dep automatically uses the ^ operator by default. dep ensure will interpret the given version as the min-boundry of a range, for example:

1.2.3 becomes the range >=1.2.3, <2.0.0
0.2.3 becomes the range >=0.2.3, <0.3.0
0.0.3 becomes the range >=0.0.3, <0.1.0

Feedback

Feedback is greatly appreciated. At this stage, the maintainers are most interested in feedback centered on the user experience (UX) of the tool. Do you have workflows that the tool supports well, or doesn't support at all? Do any of the commands have surprising effects, output, or results? Please check the existing issues and FAQ to see if your feedback has already been reported. If not, please file an issue, describing what you did or wanted to do, what you expected to happen, and what actually happened.

Contributing

Contributions are greatly appreciated. The maintainers actively manage the issues list, and try to highlight issues suitable for newcomers. The project follows the typical GitHub pull request model. See CONTRIBUTING.md for more details. Before starting any work, please either comment on an existing issue, or file a new one.