Go net/http.ServeMux and Trailing Slashes

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2024-09-29 15:00:17

It's a Thursday morning. Everything in this project has been going smoothly. Almost too smoothly. Then go test is run to make sure that things are working like we expect.

Then a moment of inspiration hit and part of the net/http.ServeMux documentation came to mind. A ServeMux is basically a type that lets you associate HTTP paths with handler functions, kinda like this:

Patterns name fixed, rooted paths, like "/favicon.ico", or rooted subtrees, like "/images/" (note the trailing slash). Longer patterns take precedence over shorter ones, so that if there are handlers registered for both "/images/" and "/images/thumbnails/", the latter handler will be called for paths beginning "/images/thumbnails/" and the former will receive requests for any other paths in the "/images/" subtree.

If a subtree has been registered and a request is received naming the subtree root without its trailing slash, ServeMux redirects that request to the subtree root (adding the trailing slash). This behavior can be overridden with a separate registration for the path without the trailing slash. For example, registering "/images/" causes ServeMux to redirect a request for "/images" to "/images/", unless "/images" has been registered separately.