Use govendor to implement vendoring

The meaning of vendoring in Go is squeezing a project's all dependencies into its vendor directory. Since Go 1.6, if there is a vendor directory in current package or its parent's directory, the dependency will be searched in vendor directory first. Govendor is such a tool to help you make use of the vendor feature. In the following example, I will demonstrate how to use govendor step by step:

(1) To be more clear, I clean $GOPATH folder first:

# tree
.

0 directories, 0 files

(2) I still use playstack project to do a demo, download it:

# go get github.com/NanXiao/playstack/play
# tree
.
├── bin
│   └── play
├── pkg
│   └── linux_amd64
│       └── github.com
│           └── NanXiao
│               └── stack.a
└── src
    └── github.com
        └── NanXiao
            ├── playstack
            │   ├── LICENSE
            │   └── play
            │       └── main.go
            └── stack
                ├── LICENSE
                ├── README.md
                ├── stack.go
                └── stack_test.go

11 directories, 8 files

The playstack depends on another 3rd-party package: stack.

(3) Install govendor:

# go get -u github.com/kardianos/govendor

(4) Change to playstack directory, and run "govendor init" command:

# cd src/github.com/NanXiao/playstack/
# govendor init
# tree
.
├── LICENSE
├── play
│   └── main.go
└── vendor
    └── vendor.json

2 directories, 3 files

You can see there is an additional vendor folder which contains vendor.json file:

# cat vendor/vendor.json
{
        "comment": "",
        "ignore": "test",
        "package": [],
        "rootPath": "github.com/NanXiao/playstack"
}

(5) Execute "govendor add +external" command:

# govendor add +external
# tree
.
├── LICENSE
├── play
│   └── main.go
└── vendor
    ├── github.com
    │   └── NanXiao
    │       └── stack
    │           ├── LICENSE
    │           ├── README.md
    │           └── stack.go
    └── vendor.json

Yeah, the stack project is copied to vendor directory now. Look at vendor/vendor.json file again:

# cat vendor/vendor.json
{
        "comment": "",
        "ignore": "test",
        "package": [
                {
                        "checksumSHA1": "3v5ClsvqF5lU/3E3c+1gf/zVeK0=",
                        "path": "github.com/NanXiao/stack",
                        "revision": "bfb214dbdb387d1c561b3b6f305ee0d8444c864b",
                        "revisionTime": "2016-04-01T05:28:44Z"
                }
        ],
        "rootPath": "github.com/NanXiao/playstack"
}

The stack package info has been updated in vendor/vendor.json file.

Notice: "govendor add" copies packages from $GOPATH, and you can use "govendor fetch" to download packages from network. You can verify it through removing stack package in $GOPATH, and execute "govendor fetch github.com/NanXiao/stack" command.

(6) Update playstack in github:

This time, clean $GOPATH folder and run "go get github.com/NanXiao/playstack/play" again:

# go get github.com/NanXiao/playstack/play
# tree
.
├── bin
│   └── play
├── pkg
│   └── linux_amd64
│       └── github.com
│           └── NanXiao
│               └── playstack
│                   └── vendor
│                       └── github.com
│                           └── NanXiao
│                               └── stack.a
└── src
    └── github.com
        └── NanXiao
            └── playstack
                ├── LICENSE
                ├── play
                │   └── main.go
                └── vendor
                    ├── github.com
                    │   └── NanXiao
                    │       └── stack
                    │           ├── LICENSE
                    │           ├── README.md
                    │           └── stack.go
                    └── vendor.json

18 directories, 8 files

Compared to previous case, it is no need to store stack in $GOPATH/src/github.com/NanXiao directory, since playstack has embedded it in its vendor folder.

This is just a simple intro of govendor, for more commands' usages, you should visit its project home page.

Reference:
What does the term “vendoring” or “to vendor” mean for Ruby on Rails?;
Understanding and using the vendor folder;
Go Vendoring Beginner Tutorial.