Package Management in Go for NPM users

Introduction

• Similar to npm init you have go mod init
• This will create go.mod which:
  • Has all the dependencies and their respective versions listed in it
  • Sort of package.json and package-lock.json combined in one file

Installing a Dependency

Similar to npm install you have go get url@version.

• Installing a git tag — go get github.com/go-chi/chi@v4
• Installing a branch — go get github.com/go-chi/chi@@master
• Installing a commit hash — go get github.com/go-chi/chi@@aac20cc

After installing a dependency, if you look at the go.mod file, you might see some of the dependencies listed as

github.com/go-chi/chi@v4.0.1+incompatible // indirect

• +incompatible here either means that the package has not opted to use the go modules yet or it violates some versioning guidelines
• // indirect means that the package has been installed but isn’t used anywhere in the project yet or it will also be listed in front of the indirect dependencies of the packages that have not opted to use go modules yet.

When you install a package, you might see that it created go.sum file in the repository which contains the cryptographic checksums of the packages installed which is used for validation purposes.

Caching the dependencies

Running go mod download will download all the dependencies and cache them locally which could make CI faster.

Removing unused packages

• Similar to npm prune, you have go mod tidy
• Running go mod tidy will remove all the unused packages or remove // indirect from the modules that are being used
• Also it can install any required dependencies depending upon the combinations of OS, architecture and build tags

Updating Package Versions

• Run go get -u to update the minor package versions
• Run go get -u=patch to update the patch versions
• Major versions have to be updated manually in the go.mod file

Substituing Imported Modules

Point a required module to your own fork or even local file path using replace directive:

go mod edit -replace github.com/go-chi/chi=./packages/chi

Remove the replacement

go mod edit -dropreplace github.com/go-chi/chi