What does this command do 'GOFLAGS=-mod=mod'?

Issue

I am trying to make a Taskfile.yml file for building go application, but I can’t quite understand the need of "GOFLAGS=-mod=mod" command before go build main.go.

reference: https://dev.to/aurelievache/learning-go-by-examples-part-3-create-a-cli-app-in-go-1h43

Solution

So there are two things here

  • GOFLAGS
    • this is nothing but an environment variable(if you don’t understand what an environment variable is, think of it like a value that can be accessed by any process in your current environment. These values are maintained by the OS).
    • So this GOFLAGS variable has a space separated list of flags that will automatically be passed to the appropriate go commands.
    • The flag we are setting here is mod, this flag is applicable to the go build command and may not be applicable to other go commands.
    • If you are curious how go does this, refer to this change request
  • what does setting -mod=mod flag, actually do during go build?
    • The -mod flag controls whether go.mod may be automatically updated and whether the vendor directory is used.
    • -mod=mod tells the go command to ignore the vendor directory and to automatically update go.mod, for example, when an imported package is not provided by any known module.
    • Refer this.

Therefore

GOFLAGS="-mod=mod" go build main.go

is equivalent to

go build -mod=mod main.go

Answered By – Aswin Thiyagarajan

Answer Checked By – Clifford M. (GoLangFix Volunteer)

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