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** REVIEW REQUIRED **

This guide is a WIP.

Intro

How do you handle the situation where a library you want to use has moved onto a major version >= 2 but is yet to migrate to vgo? This guide shows you how, by using github.com/labstack/echo as an example.

A further point to note is that, at the time of writing, https://github.com/labstack/echo tagged their releases differently after v3.2.1. v3.2.1 was tagged as v3.2.1, whereas v3.2.2 was tagged as 3.2.2 (note the missing v); and this new pattern was used for all releases up to and including (at the time of writing) v3.3.5 which was tagged as 3.3.5. vgo doesn't recognise these tags (e.g. 3.3.5) as versions, and hence this guide is written against v3.2.1.

A simple example

We will use a simple example taken from the package README for this guide. We start by creating a new directory for our example:

$ mkdir hello
$ cd hello

Next we write out the example and create an empty go.mod file to mark this as a vgo module:

$ cat <<EOD >main.go
package main

import (
	"net/http"

	"github.com/labstack/echo"
	"github.com/labstack/echo/middleware"
)

func main() {
	// Echo instance
	e := echo.New()

	// Middleware
	e.Use(middleware.Logger())
	e.Use(middleware.Recover())

	// Routes
	e.GET("/", hello)

	// Start server
	e.Logger.Fatal(e.Start(":1323"))
}

// Handler
func hello(c echo.Context) error {
	return c.String(http.StatusOK, "Hello, World!")
}
EOD
$ go mod init example.com/hello
go: creating new go.mod: module example.com/hello

Now, we explicitly add github.com/labstack/[email protected] as a requirement:

$ go get github.com/labstack/[email protected]
go: finding github.com/labstack/echo v3.2.1
go: downloading github.com/labstack/echo v3.2.1+incompatible
go: finding github.com/labstack/gommon/color latest
go: finding github.com/labstack/gommon/log latest
go: finding golang.org/x/crypto/acme/autocert latest
go: finding golang.org/x/crypto/acme latest
go: finding golang.org/x/crypto latest
go: downloading golang.org/x/crypto v0.0.0-20181106171534-e4dc69e5b2fd
go: finding github.com/labstack/gommon v0.2.7
go: downloading github.com/labstack/gommon v0.2.7
go: finding github.com/mattn/go-isatty v0.0.4
go: finding github.com/valyala/fasttemplate latest
go: finding github.com/mattn/go-colorable v0.0.9
go: downloading github.com/mattn/go-isatty v0.0.4
go: downloading github.com/mattn/go-colorable v0.0.9
go: downloading github.com/valyala/fasttemplate v0.0.0-20170224212429-dcecefd839c4
go: finding github.com/valyala/bytebufferpool v1.0.0
go: downloading github.com/valyala/bytebufferpool v1.0.0

Notice how this actually resolves to a v0.0.0 pseudo-version.

Now as a final step we build to confirm everything works:

$ go build
go: finding github.com/dgrijalva/jwt-go v3.2.0+incompatible
go: downloading github.com/dgrijalva/jwt-go v3.2.0+incompatible
go: finding github.com/labstack/echo v3.2.1+incompatible
$ cat go.mod
module example.com/hello

require (
	github.com/dgrijalva/jwt-go v3.2.0+incompatible // indirect
	github.com/labstack/echo v3.2.1+incompatible
	github.com/labstack/gommon v0.2.7 // indirect
	github.com/mattn/go-colorable v0.0.9 // indirect
	github.com/mattn/go-isatty v0.0.4 // indirect
	github.com/valyala/bytebufferpool v1.0.0 // indirect
	github.com/valyala/fasttemplate v0.0.0-20170224212429-dcecefd839c4 // indirect
	golang.org/x/crypto v0.0.0-20181106171534-e4dc69e5b2fd // indirect
)

Et voila.

Version details

go version go1.11.2 linux/amd64