httpmux

httpmux is an http request multiplexer for Go built on top of the popular httprouter, with modern features.

The main motivation is to bring http handlers back to their original Handler interface as defined by net/http but leverage the speed and features of httprouter, such as dispatching handlers by method and handling HTTP 405 automatically.

Another important aspect of httpmux is that it provides request context for arbitrary data, such as httprouter's URL parameters. Seasoned gophers migth immediately think this is an overlap of gorilla's context package, however, their implementation rely on global variables and mutexes that can cause contention on heavily loaded systems. We use a different approach, which was stolen from httpway, that hijacks the http.Request's Body field and replace it with an object that is an io.ReadCloser but also carries a net/context object. This works well for middleware that wants to store arbitrary data in the request, serial, and once it hits your handler, the context can be passed around to goroutines. It is automatically cleared at the end of the middleware chain.

There's been discussions for adding net/context to the standard library but most options require changing or creating a new interface and/or function signature for http handlers. In httpmux we remain close to net/http aiming at being more pluggable and composable with existing code in the wild, and if the Request type ends up getting a Context field, will be an easy change in httpmux.

To make contexts more useful, httpmux provides the ability to register and chain wrapper handlers, middleware. Our implementation is based on blogs and especially chi, but much smaller.

Last but not least, httpmux offers two more features for improving composability. First, is to configure a global prefix for all handlers in the multiplexer. This is for cases when you have to run your API behind a proxy, or mixed with other services, and have to be able to parse and understand the prefix in your handlers. Second, is to allow subtrees like gin's groups, but in a more composable way. Think of cases where your code is an independent package that provides an http handler, that is tested and run isolated, but can be added to a larger API at run time. In chi, this is equivalent to the Mount function in their router.