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

dep will analyize your project, identify your dependencies, pick the highest compatible version for each dependency, generate a Gopkg.toml manifest and Gopkg.lock files (see here for background on the two file format), and install dependencies in vendor/.

$ dep init

Notes:

1. If you are already using glide, godep, vndr, or govend, dep will convert the existing dependency management file. See this issue and this interface for implementing configuration importers.
2. If you have an existing vendor/ directory, it will be backed up to _vendor-TIMESTAMP/.

$ dep ensure

dep's solver regenerates Gopkg.lock if it detects any change in your code imports and/or Gopkg.toml. If this is the case, then the new Gopkg.lock file is used to completely rewrite vendor/ (at some point vednor verification will allow the contents of vendor/ to also be checked for consistency with Gopkg.lock, updating only what is necessary to make the contents current.

Note:

This process may be slow for large projects, especially the first time as dependencies are cloned or when it hasn't been run in a while and there are many changesets to fetch. dep manages a cache at $GOPATH/pkg/dep to mitigate fetch overhead. See here for further details.

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

dep will update your Gopkg.toml, Gopkg.lock, and vendor/.

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