Go modules are not found using VGO and go.mod

Question

I'm using versioned Go command to manage my vendors, everything is working but when I run go build it doesn't find my local packages

I have set the module root inside my go.mod with I still get an error

build foo: cannot find module for path

The project arch is like

foo/
|__src/github.com/username/package1/package1.go
|__src/github.com/username/package2/package2.go
|__src/github.com/username/package3/package3.go
|__main.go
|__go.mod
|__go.sum

So my go.mod look like

module foo

require (
    ...
)

I followed https://research.swtch.com/vgo-tour but I don't understand why this is not working.

My Go version is 1.11 and the foo folder is inside my GOPATH when I try outside the GOPATH this is not even working.

The only time I made it work is doing

module github.com/username/package1

require (
    ...
)

but the 2 other packages are not found and I get the same error as above.

Did I miss something or do the module path I provide must be changed ?

Answer 1

I assume your local packages imported are wrong, follow my example.

There is my go.mod (outside of GOPATH, I've imported mux for example):

module example

require github.com/gorilla/mux v1.6.2 // indirect

BTW you can create an empty go.mod, go will find and update your go.mod for you.

The main.go:

package main

import (
    _ "example/src/foo" // local package
    "fmt"
    _ "github.com/gorilla/mux" // example import
)

func main() {
    fmt.Println("foo")
}

The foo local package:

package foo

import "fmt"

func bar() {
    fmt.Println("foo")
}

The module tree:

├── go.mod
├── go.sum
├── main.go
└── src
    └── foo
        └── foo.go

You can find more explanation here Modules