kovetskiy / manul

:smirk_cat: The madness vendoring utility for Golang programs

MANUL

Manul is a vendoring utility for Go programs.

Installation

manul can be obtained using go get:

go get github.com/kovetskiy/manul

Packages are also available for Ubuntu/Debian and Arch Linux.

What's the reason for yet another utility?

Because all other vendor utilities suffer from the following:

• Some wrap the go binary and spoof the GOPATH env variable. You will have a non-go-gettable project which needs additional software in order to compile and run;

• Some copy the source code of dependencies into the vendor directory:

  • It will be nearly impossible to find anything using GitHub Search, because you will get many false-positive results;
  • Updating dependencies will require manual intervention and committing a lot of modified lines straight into the main repo;
  • You will not be able to tell what version of dependency your project is using will by looking at repository; you have to keep versions in the additional ambiguous file with vendors associated with commits.

• Various architecture problems:

  • Impossible to update all or specific vendored dependencies;
  • Impossible to rollback vendored dependencies to specific version;
  • Impossible to remove unused vendored dependencies;
  • Impossible to lock version of vendored dependency.

Solution

We all love git, it's a very powerful instrument. Why don't we use its power for vendoring dependencies using an awesome feature, which is called git submodule?

With git submodule you will have a git repository for each dependency. They can be managed in the same way as main project by git.

Pros:

• No need for additional software for building/running your Go project;

• No need for additional JSON/TOML/YAML file for storing dependencies;

• Update vendored dependencies directly from remote origins;

• Rollback changes in dependencies;

• Go-gettable

git submodule might look like a Silver Bullet, but it's still clumsy to work with manually. We want to have a powerful yet simple interface for vendoring dependencies using this technology.

manul can do it for us.

Usage

Who needs a documentation when there are GIFs?

First of all, we should request dependencies which we have in our project. To do this, just run manul with -Q (query) flag. It will output all the project imports (dependencies), like this:

For example, we have six dependencies, let's lock versions of critical dependencies by adding submodules: in our case it's zhash and blackfriday packages.

For locking versions (installing dependencies) we should use -I (install) flag and specify dependencies, which we wish to install:

After installation we can have a look for vendored and non-vendored dependencies by using flag -Q. After previous step we should see git commits along with two already vendored dependencies (zhash and blackfriday):

Let's install submodules for remaining dependencies, go the limit! Just run manul with flag -I without specifying any dependencies, manul will install all detected dependencies with skipping already vendored:

Wow, that was crazy! Now, to update some vendored dependencies, for example, docopt-go package, manul should be invoked with the flag -U and import path (github.com/docopt/docopt-go):

manul can be used to remove specified submodules of vendored dependencies by using -R (remove) flag and specifying dependencies import path:

By the way, manul can detect and remove unused vendored dependencies using -C (clean) flag:

manul can also get you a specific version of a dependency by using a commit-ish, for example:

• manul -I golang.org/x/foo=34a235h1 will install foo at the specified commit
• manul -U github.com/x/bar=this-tag will update it to this-tag version.

Let's summarize:

• -I [<dependency>...] - install git submodules for specified/all dependencies;
• -U [<dependency>...] - update specified/all already vendored dependencies;
• -R [<dependency>...] - remove git submodules for specified/all dependencies;
• -Q [<dependency>...] - list all used dependencies;
• -C - detect and remove all git submodules for unused vendored dependencies.

You can see similar help message by passing -h or --help flag.