Goji

Goji is a minimalistic web framework that values composability and simplicity.

This project has been superseded by a new version of Goji by the same author, which has very similar primitives and semantics, but has been updated to reflect several years of experience with this library and the surrounding Go ecosystem. This project is still well-loved and well-maintained, and will be for the foreseeable future, but new projects are encouraged to use goji.io instead.

Example

package main

import (
        "fmt"
        "net/http"

        "github.com/zenazn/goji"
        "github.com/zenazn/goji/web"
)

func hello(c web.C, w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "Hello, %s!", c.URLParams["name"])
}

func main() {
        goji.Get("/hello/:name", hello)
        goji.Serve()
}

Goji also includes a sample application in the example folder which was artificially constructed to show off all of Goji's features. Check it out!

Features

Compatible with net/http
URL patterns (both Sinatra style /foo/:bar patterns and regular expressions, as well as custom patterns)
Reconfigurable middleware stack
Context/environment object threaded through middleware and handlers
Automatic support for Einhorn, systemd, and more
Graceful shutdown, and zero-downtime graceful reload when combined with Einhorn.
High in antioxidants

Stability

Goji's API is essentially frozen, and guarantees to never break compatibility with existing code (under similar rules to the Go project's guidelines). Goji is suitable for use in production, and has served billions of requests across several companies.

Is it any good?

Maybe!

There are plenty of other good Go web frameworks out there. Goji is by no means especially novel, nor is it uniquely good. The primary difference between Goji and other frameworks—and the primary reason I think Goji is any good—is its philosophy:

Goji first of all attempts to be simple. It is of the Sinatra and Flask school of web framework design, and not the Rails/Django one. If you want me to tell you what directory you should put your models in, or if you want built-in flash sessions, you won't have a good time with Goji.

Secondly, Goji attempts to be composable. It is fully composable with net/http, and can be used as a http.Handler, or can serve arbitrary http.Handlers. At least a few HTTP frameworks share this property, and is not particularly novel. The more interesting property in my mind is that Goji is fully composable with itself: it defines an interface (web.Handler) which is both fully compatible with http.Handler and allows Goji to perform a "protocol upgrade" of sorts when it detects that it is talking to itself (or another web.Handler compatible component). web.Handler is at the core of Goji's interfaces and is what allows it to share request contexts across unrelated objects.

Third, Goji is not magic. One of my favorite existing frameworks is Martini, but I rejected it in favor of building Goji because I thought it was too magical. Goji's web package does not use reflection at all, which is not in itself a sign of API quality, but to me at least seems to suggest it.

Finally, Goji gives you enough rope to hang yourself with. One of my other favorite libraries, pat, implements Sinatra-like routing in a particularly elegant way, but because of its reliance on net/http's interfaces, doesn't allow programmers to thread their own state through the request handling process. Implementing arbitrary context objects was one of the primary motivations behind abandoning pat to write Goji.

Is it fast?

Yeah, it is. Goji is among the fastest HTTP routers out there, and is very gentle on the garbage collector.

But that's sort of missing the point. Almost all Go routers are fast enough for almost all purposes. In my opinion, what matters more is how simple and flexible the routing semantics are.

Goji provides results indistinguishable from naively trying routes one after another. This means that a route added before another route will be attempted before that route as well. This is perhaps the most simple and most intuitive interface a router can provide, and makes routes very easy to understand and debug.

Goji's router is also very flexible: in addition to the standard Sinatra-style patterns and regular expression patterns, you can define custom patterns to perform whatever custom matching logic you desire. Custom patterns of course are fully compatible with the routing semantics above.

It's easy (and quite a bit of fun!) to get carried away by microbenchmarks, but at the end of the day you're not going to miss those extra hundred nanoseconds on a request. What matters is that you aren't compromising on the API for a handful of CPU cycles.

Third-Party Libraries

Goji is already compatible with a great many third-party libraries that are themselves compatible with net/http, however some library authors have gone out of their way to include Goji compatibility specifically, perhaps by integrating more tightly with Goji's web.C or by providing a custom pattern type. An informal list of such libraries is maintained on the wiki; feel free to add to it as you see fit.

Contributing

Please do! I love pull requests, and I love pull requests that include tests even more. Goji's core packages have pretty good code coverage (yay code coverage gamification!), and if you have the time to write tests I'd like to keep it that way.

In addition to contributing code, I'd love to know what you think about Goji. Please open an issue or send me an email with your thoughts; it'd mean a lot to me.

zenazn / goji