为什么使用govendor

go语言的依赖管理最主要的是版本控制问题。
govendor是Golang的依赖包管理工具，它的出现可以避免不同用户在clone同一个项目后从外部获取不同依赖库版本的问题。
govendor会将项目需要的依赖包添加到项目的vendor目录下，并且该目录中vendor.json文件会保存添加的依赖包的路径等信息。
Golang项目中的go文件在查找依赖的顺序是，先在vendor中查找，vendor没找到然后在GOPATH中查找，都没找到最后在GOROOT中查找。
govendor只是用来管理项目的依赖包，如果GOPATH中本身没有项目的依赖包，则需要通过go get先下载到GOPATH中，再通过govendor add +external拷贝到vendor目录中。

基本用法

安装govendor：go get -u github.com/kardianos/govendor
如果需要使用vendor的项目原本没有vendor，那么需要在该项目的目录下创建vendor
govendor init
之后如果需要添加依赖包，可以通过以下两种方式添加
govendor fetch 依赖包路径
govendor add 依赖包路径

.gitignore的配置：

/vendor/*
!/vendor/vendor.json

根据vendor.json下载依赖：govendor sync

govendor用法例子：

cd path/to/project
govendor init
govendor fetch project_url_with_out_http
cat vendor/vendor.json

govendor常用命令

• 增加包，搜add，会得到add和fetch这2个命令。
• 更新包，搜update，会得到update和fetch这2个命令。
• 删除包，搜remove，得到remove这个命令。
• 查看已经依赖的包，搜list，得到list、status、license命令，而符合你的是list，并且知道了status能列出过期的包。

➜  project_name git:(develop) govendor --help
govendor (v1.0.9): record dependencies and copy into vendor folder-govendor-licenses    Show govendor's licenses.-version              Show govendor version-cpuprofile 'file'    Writes a CPU profile to 'file' for debugging.-memprofile 'file'    Writes a heap profile to 'file' for debugging.Sub-Commandsinit     Create the "vendor" folder and the "vendor.json" file.list     List and filter existing dependencies and packages.add      Add packages from $GOPATH.update   Update packages from $GOPATH.remove   Remove packages from the vendor folder.status   Lists any packages missing, out-of-date, or modified locally.fetch    Add new or update vendor folder packages from remote repository.sync     Pull packages into vendor folder from remote repository with revisionsfrom vendor.json file.migrate  Move packages from a legacy tool to the vendor folder with metadata.get      Like "go get" but copies dependencies into a "vendor" folder.license  List discovered licenses for the given status or import paths.shell    Run a "shell" to make multiple sub-commands more efficient for largeprojects.go tool commands that are wrapped:"+status" package selection may be used with themfmt, build, install, clean, test, vet, generate, toolStatus Types+local    (l) packages in your project+external (e) referenced packages in GOPATH but not in current project+vendor   (v) packages in the vendor folder+std      (s) packages in the standard library+excluded (x) external packages explicitly excluded from vendoring+unused   (u) packages in the vendor folder, but unused+missing  (m) referenced packages but not found+program  (p) package is a main package+outside  +external +missing+all      +all packagesStatus can be referenced by their initial letters.Package specifier<path>[::<origin>][{/...|/^}][@[<version-spec>]]Ignoring files with build tags, or excluding packages from being vendored:The "vendor.json" file contains a string field named "ignore".It may contain a space separated list of build tags to ignore whenlisting and copying files.This list may also contain package prefixes (containing a "/", possiblyas last character) to exclude when copying files in the vendor folder.If "foo/" appears in this field, then package "foo" and all its sub-packages("foo/bar", …) will be excluded (but package "bar/foo" will not).By default the init command adds the "test" tag to the ignore list.If using go1.5, ensure GO15VENDOREXPERIMENT=1 is set.