as handling other paths may be desirable

Why don't we return the index handler from pprof.Handler("index")? It doesn't solve the issue of /debug/pprof paths will be registered as a side effect when you import the package but gives flexibility to serve the index handler from a different route.

Right now you can get at the handler with a call to something like http.HandleFunc("/debug/pprof", http.HandlerFunc(pprof.Index)), so I don't think the extra pprof.Handler("index") behaviour is worth the hassle of having to forbid "index" as a profile name.

The problem, really, is that if you choose to serve it from a different route, it's broken.

The problem, really, is that if you choose to serve it from a different route, it's broken.

You can serve it from a different route:

http.Handle("/custom/pprof", http.HandlerFunc(pprofhttp.Index))

init registers the routes on the DefaultServeMux, if you use a custom ServeMux, you don't also have to serve the /debug/pprof endpoints.

package main

import (
    "log"
    "net/http"
    pprofhttp "net/http/pprof"
)

func main() {
    mux := http.NewServeMux()
    mux.Handle("/custom/pprof", http.HandlerFunc(pprofhttp.Index))
    log.Println(http.ListenAndServe("localhost:6060", mux))
}

I don't quite think we can do anything else without breaking the current users.

I got confused because you have mentioned the index handler only initially, the same applies to other pprof endpoints.

if strings.HasPrefix(r.URL.Path, "/debug/pprof/")

Please ignore my previous comment. I lost the background, haven't seen the line and was replying without context.

Why don't you just write a custom index handler or register the routes manually if you don't have many custom profiles? The optimistic matching from the path is a bit magical and polluting the API surface is the last thing we should consider. The index handler is just a few lines of code and easy to replicate.

I'd rather not go down this road.

The package docs already say:

The handled paths all begin with /debug/pprof/

This package is quite small. If you want something different, it's easy enough to fork it. I don't want to bloat the package (in either API or implementation) by supporting too much flexibility. The nice things about conventions (like /debug/*) is that it permits simplicity elsewhere.