mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-10 15:44:05 -08:00
324 lines
14 KiB
Markdown
324 lines
14 KiB
Markdown
|
# HttpRouter [](https://travis-ci.org/julienschmidt/httprouter) [](http://gocover.io/github.com/julienschmidt/httprouter) [](http://godoc.org/github.com/julienschmidt/httprouter)
|
||
|
|
|
||
|
|
HttpRouter is a lightweight high performance HTTP request router
|
||
|
|
(also called *multiplexer* or just *mux* for short) for [Go](http://golang.org/).
|
||
|
|
|
||
|
|
In contrast to the [default mux](http://golang.org/pkg/net/http/#ServeMux) of Go's net/http package, this router supports
|
||
|
|
variables in the routing pattern and matches against the request method.
|
||
|
|
It also scales better.
|
||
|
|
|
||
|
|
The router is optimized for high performance and a small memory footprint.
|
||
|
|
It scales well even with very long paths and a large number of routes.
|
||
|
|
A compressing dynamic trie (radix tree) structure is used for efficient matching.
|
||
|
|
|
||
|
|
## Features
|
||
|
|
**Only explicit matches:** With other routers, like [http.ServeMux](http://golang.org/pkg/net/http/#ServeMux),
|
||
|
|
a requested URL path could match multiple patterns. Therefore they have some
|
||
|
|
awkward pattern priority rules, like *longest match* or *first registered,
|
||
|
|
first matched*. By design of this router, a request can only match exactly one
|
||
|
|
or no route. As a result, there are also no unintended matches, which makes it
|
||
|
|
great for SEO and improves the user experience.
|
||
|
|
|
||
|
|
**Stop caring about trailing slashes:** Choose the URL style you like, the
|
||
|
|
router automatically redirects the client if a trailing slash is missing or if
|
||
|
|
there is one extra. Of course it only does so, if the new path has a handler.
|
||
|
|
If you don't like it, you can [turn off this behavior](http://godoc.org/github.com/julienschmidt/httprouter#Router.RedirectTrailingSlash).
|
||
|
|
|
||
|
|
**Path auto-correction:** Besides detecting the missing or additional trailing
|
||
|
|
slash at no extra cost, the router can also fix wrong cases and remove
|
||
|
|
superfluous path elements (like `../` or `//`).
|
||
|
|
Is [CAPTAIN CAPS LOCK](http://www.urbandictionary.com/define.php?term=Captain+Caps+Lock) one of your users?
|
||
|
|
HttpRouter can help him by making a case-insensitive look-up and redirecting him
|
||
|
|
to the correct URL.
|
||
|
|
|
||
|
|
**Parameters in your routing pattern:** Stop parsing the requested URL path,
|
||
|
|
just give the path segment a name and the router delivers the dynamic value to
|
||
|
|
you. Because of the design of the router, path parameters are very cheap.
|
||
|
|
|
||
|
|
**Zero Garbage:** The matching and dispatching process generates zero bytes of
|
||
|
|
garbage. In fact, the only heap allocations that are made, is by building the
|
||
|
|
slice of the key-value pairs for path parameters. If the request path contains
|
||
|
|
no parameters, not a single heap allocation is necessary.
|
||
|
|
|
||
|
|
**Best Performance:** [Benchmarks speak for themselves](https://github.com/julienschmidt/go-http-routing-benchmark).
|
||
|
|
See below for technical details of the implementation.
|
||
|
|
|
||
|
|
**No more server crashes:** You can set a [Panic handler](http://godoc.org/github.com/julienschmidt/httprouter#Router.PanicHandler) to deal with panics
|
||
|
|
occurring during handling a HTTP request. The router then recovers and lets the
|
||
|
|
PanicHandler log what happened and deliver a nice error page.
|
||
|
|
|
||
|
|
Of course you can also set **custom [NotFound](http://godoc.org/github.com/julienschmidt/httprouter#Router.NotFound) and [MethodNotAllowed](http://godoc.org/github.com/julienschmidt/httprouter#Router.MethodNotAllowed) handlers** and [**serve static files**](http://godoc.org/github.com/julienschmidt/httprouter#Router.ServeFiles).
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
This is just a quick introduction, view the [GoDoc](http://godoc.org/github.com/julienschmidt/httprouter) for details.
|
||
|
|
|
||
|
|
Let's start with a trivial example:
|
||
|
|
```go
|
||
|
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"github.com/julienschmidt/httprouter"
|
||
|
|
"net/http"
|
||
|
|
"log"
|
||
|
|
)
|
||
|
|
|
||
|
|
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
|
||
|
|
fmt.Fprint(w, "Welcome!\n")
|
||
|
|
}
|
||
|
|
|
||
|
|
func Hello(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
|
||
|
|
fmt.Fprintf(w, "hello, %s!\n", ps.ByName("name"))
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
router := httprouter.New()
|
||
|
|
router.GET("/", Index)
|
||
|
|
router.GET("/hello/:name", Hello)
|
||
|
|
|
||
|
|
log.Fatal(http.ListenAndServe(":8080", router))
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
### Named parameters
|
||
|
|
As you can see, `:name` is a *named parameter*.
|
||
|
|
The values are accessible via `httprouter.Params`, which is just a slice of `httprouter.Param`s.
|
||
|
|
You can get the value of a parameter either by its index in the slice, or by using the `ByName(name)` method:
|
||
|
|
`:name` can be retrived by `ByName("name")`.
|
||
|
|
|
||
|
|
Named parameters only match a single path segment:
|
||
|
|
```
|
||
|
|
Pattern: /user/:user
|
||
|
|
|
||
|
|
/user/gordon match
|
||
|
|
/user/you match
|
||
|
|
/user/gordon/profile no match
|
||
|
|
/user/ no match
|
||
|
|
```
|
||
|
|
|
||
|
|
**Note:** Since this router has only explicit matches, you can not register static routes and parameters for the same path segment. For example you can not register the patterns `/user/new` and `/user/:user` for the same request method at the same time. The routing of different request methods is independent from each other.
|
||
|
|
|
||
|
|
### Catch-All parameters
|
||
|
|
The second type are *catch-all* parameters and have the form `*name`.
|
||
|
|
Like the name suggests, they match everything.
|
||
|
|
Therefore they must always be at the **end** of the pattern:
|
||
|
|
```
|
||
|
|
Pattern: /src/*filepath
|
||
|
|
|
||
|
|
/src/ match
|
||
|
|
/src/somefile.go match
|
||
|
|
/src/subdir/somefile.go match
|
||
|
|
```
|
||
|
|
|
||
|
|
## How does it work?
|
||
|
|
The router relies on a tree structure which makes heavy use of *common prefixes*,
|
||
|
|
it is basically a *compact* [*prefix tree*](http://en.wikipedia.org/wiki/Trie)
|
||
|
|
(or just [*Radix tree*](http://en.wikipedia.org/wiki/Radix_tree)).
|
||
|
|
Nodes with a common prefix also share a common parent. Here is a short example
|
||
|
|
what the routing tree for the `GET` request method could look like:
|
||
|
|
|
||
|
|
```
|
||
|
|
Priority Path Handle
|
||
|
|
9 \ *<1>
|
||
|
|
3 ├s nil
|
||
|
|
2 |├earch\ *<2>
|
||
|
|
1 |└upport\ *<3>
|
||
|
|
2 ├blog\ *<4>
|
||
|
|
1 | └:post nil
|
||
|
|
1 | └\ *<5>
|
||
|
|
2 ├about-us\ *<6>
|
||
|
|
1 | └team\ *<7>
|
||
|
|
1 └contact\ *<8>
|
||
|
|
```
|
||
|
|
Every `*<num>` represents the memory address of a handler function (a pointer).
|
||
|
|
If you follow a path trough the tree from the root to the leaf, you get the
|
||
|
|
complete route path, e.g `\blog\:post\`, where `:post` is just a placeholder
|
||
|
|
([*parameter*](#named-parameters)) for an actual post name. Unlike hash-maps, a
|
||
|
|
tree structure also allows us to use dynamic parts like the `:post` parameter,
|
||
|
|
since we actually match against the routing patterns instead of just comparing
|
||
|
|
hashes. [As benchmarks show](https://github.com/julienschmidt/go-http-routing-benchmark),
|
||
|
|
this works very well and efficient.
|
||
|
|
|
||
|
|
Since URL paths have a hierarchical structure and make use only of a limited set
|
||
|
|
of characters (byte values), it is very likely that there are a lot of common
|
||
|
|
prefixes. This allows us to easily reduce the routing into ever smaller problems.
|
||
|
|
Moreover the router manages a separate tree for every request method.
|
||
|
|
For one thing it is more space efficient than holding a method->handle map in
|
||
|
|
every single node, for another thing is also allows us to greatly reduce the
|
||
|
|
routing problem before even starting the look-up in the prefix-tree.
|
||
|
|
|
||
|
|
For even better scalability, the child nodes on each tree level are ordered by
|
||
|
|
priority, where the priority is just the number of handles registered in sub
|
||
|
|
nodes (children, grandchildren, and so on..).
|
||
|
|
This helps in two ways:
|
||
|
|
|
||
|
|
1. Nodes which are part of the most routing paths are evaluated first. This
|
||
|
|
helps to make as much routes as possible to be reachable as fast as possible.
|
||
|
|
2. It is some sort of cost compensation. The longest reachable path (highest
|
||
|
|
cost) can always be evaluated first. The following scheme visualizes the tree
|
||
|
|
structure. Nodes are evaluated from top to bottom and from left to right.
|
||
|
|
|
||
|
|
```
|
||
|
|
├------------
|
||
|
|
├---------
|
||
|
|
├-----
|
||
|
|
├----
|
||
|
|
├--
|
||
|
|
├--
|
||
|
|
└-
|
||
|
|
```
|
||
|
|
|
||
|
|
|
||
|
|
## Why doesn't this work with http.Handler?
|
||
|
|
**It does!** The router itself implements the http.Handler interface.
|
||
|
|
Moreover the router provides convenient [adapters for http.Handler](http://godoc.org/github.com/julienschmidt/httprouter#Router.Handler)s and [http.HandlerFunc](http://godoc.org/github.com/julienschmidt/httprouter#Router.HandlerFunc)s
|
||
|
|
which allows them to be used as a [httprouter.Handle](http://godoc.org/github.com/julienschmidt/httprouter#Router.Handle) when registering a route.
|
||
|
|
The only disadvantage is, that no parameter values can be retrieved when a
|
||
|
|
http.Handler or http.HandlerFunc is used, since there is no efficient way to
|
||
|
|
pass the values with the existing function parameters.
|
||
|
|
Therefore [httprouter.Handle](http://godoc.org/github.com/julienschmidt/httprouter#Router.Handle) has a third function parameter.
|
||
|
|
|
||
|
|
Just try it out for yourself, the usage of HttpRouter is very straightforward. The package is compact and minimalistic, but also probably one of the easiest routers to set up.
|
||
|
|
|
||
|
|
|
||
|
|
## Where can I find Middleware *X*?
|
||
|
|
This package just provides a very efficient request router with a few extra
|
||
|
|
features. The router is just a [http.Handler](http://golang.org/pkg/net/http/#Handler),
|
||
|
|
you can chain any http.Handler compatible middleware before the router,
|
||
|
|
for example the [Gorilla handlers](http://www.gorillatoolkit.org/pkg/handlers).
|
||
|
|
Or you could [just write your own](http://justinas.org/writing-http-middleware-in-go/),
|
||
|
|
it's very easy!
|
||
|
|
|
||
|
|
Alternatively, you could try [a web framework based on HttpRouter](#web-frameworks-based-on-httprouter).
|
||
|
|
|
||
|
|
### Multi-domain / Sub-domains
|
||
|
|
Here is a quick example: Does your server serve multiple domains / hosts?
|
||
|
|
You want to use sub-domains?
|
||
|
|
Define a router per host!
|
||
|
|
```go
|
||
|
|
// We need an object that implements the http.Handler interface.
|
||
|
|
// Therefore we need a type for which we implement the ServeHTTP method.
|
||
|
|
// We just use a map here, in which we map host names (with port) to http.Handlers
|
||
|
|
type HostSwitch map[string]http.Handler
|
||
|
|
|
||
|
|
// Implement the ServerHTTP method on our new type
|
||
|
|
func (hs HostSwitch) ServeHTTP(w http.ResponseWriter, r *http.Request) {
|
||
|
|
// Check if a http.Handler is registered for the given host.
|
||
|
|
// If yes, use it to handle the request.
|
||
|
|
if handler := hs[r.Host]; handler != nil {
|
||
|
|
handler.ServeHTTP(w, r)
|
||
|
|
} else {
|
||
|
|
// Handle host names for wich no handler is registered
|
||
|
|
http.Error(w, "Forbidden", 403) // Or Redirect?
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
// Initialize a router as usual
|
||
|
|
router := httprouter.New()
|
||
|
|
router.GET("/", Index)
|
||
|
|
router.GET("/hello/:name", Hello)
|
||
|
|
|
||
|
|
// Make a new HostSwitch and insert the router (our http handler)
|
||
|
|
// for example.com and port 12345
|
||
|
|
hs := make(HostSwitch)
|
||
|
|
hs["example.com:12345"] = router
|
||
|
|
|
||
|
|
// Use the HostSwitch to listen and serve on port 12345
|
||
|
|
log.Fatal(http.ListenAndServe(":12345", hs))
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
### Basic Authentication
|
||
|
|
Another quick example: Basic Authentification (RFC 2617) for handles:
|
||
|
|
|
||
|
|
```go
|
||
|
|
package main
|
||
|
|
|
||
|
|
import (
|
||
|
|
"bytes"
|
||
|
|
"encoding/base64"
|
||
|
|
"fmt"
|
||
|
|
"github.com/julienschmidt/httprouter"
|
||
|
|
"net/http"
|
||
|
|
"log"
|
||
|
|
"strings"
|
||
|
|
)
|
||
|
|
|
||
|
|
func BasicAuth(h httprouter.Handle, user, pass []byte) httprouter.Handle {
|
||
|
|
return func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
|
||
|
|
const basicAuthPrefix string = "Basic "
|
||
|
|
|
||
|
|
// Get the Basic Authentication credentials
|
||
|
|
auth := r.Header.Get("Authorization")
|
||
|
|
if strings.HasPrefix(auth, basicAuthPrefix) {
|
||
|
|
// Check credentials
|
||
|
|
payload, err := base64.StdEncoding.DecodeString(auth[len(basicAuthPrefix):])
|
||
|
|
if err == nil {
|
||
|
|
pair := bytes.SplitN(payload, []byte(":"), 2)
|
||
|
|
if len(pair) == 2 &&
|
||
|
|
bytes.Equal(pair[0], user) &&
|
||
|
|
bytes.Equal(pair[1], pass) {
|
||
|
|
|
||
|
|
// Delegate request to the given handle
|
||
|
|
h(w, r, ps)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Request Basic Authentication otherwise
|
||
|
|
w.Header().Set("WWW-Authenticate", "Basic realm=Restricted")
|
||
|
|
http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
|
||
|
|
fmt.Fprint(w, "Not protected!\n")
|
||
|
|
}
|
||
|
|
|
||
|
|
func Protected(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
|
||
|
|
fmt.Fprint(w, "Protected!\n")
|
||
|
|
}
|
||
|
|
|
||
|
|
func main() {
|
||
|
|
user := []byte("gordon")
|
||
|
|
pass := []byte("secret!")
|
||
|
|
|
||
|
|
router := httprouter.New()
|
||
|
|
router.GET("/", Index)
|
||
|
|
router.GET("/protected/", BasicAuth(Protected, user, pass))
|
||
|
|
|
||
|
|
log.Fatal(http.ListenAndServe(":8080", router))
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
## Chaining with the NotFound handler
|
||
|
|
|
||
|
|
**NOTE: It might be required to set [Router.HandleMethodNotAllowed](http://godoc.org/github.com/julienschmidt/httprouter#Router.HandleMethodNotAllowed) to `false` to avoid problems.**
|
||
|
|
|
||
|
|
You can use another [http.Handler](http://golang.org/pkg/net/http/#Handler), for example another router, to handle requests which could not be matched by this router by using the [Router.NotFound](http://godoc.org/github.com/julienschmidt/httprouter#Router.NotFound) handler. This allows chaining.
|
||
|
|
|
||
|
|
### Static files
|
||
|
|
The `NotFound` handler can for example be used to serve static files from the root path `/` (like an index.html file along with other assets):
|
||
|
|
```go
|
||
|
|
// Serve static files from the ./public directory
|
||
|
|
router.NotFound = http.FileServer(http.Dir("public")).ServeHTTP
|
||
|
|
```
|
||
|
|
|
||
|
|
But this approach sidesteps the strict core rules of this router to avoid routing problems. A cleaner approach is to use a distinct sub-path for serving files, like `/static/*filepath` or `/files/*filepath`.
|
||
|
|
|
||
|
|
## Web Frameworks based on HttpRouter
|
||
|
|
If the HttpRouter is a bit too minimalistic for you, you might try one of the following more high-level 3rd-party web frameworks building upon the HttpRouter package:
|
||
|
|
* [Ace](https://github.com/plimble/ace): Blazing fast Go Web Framework
|
||
|
|
* [api2go](https://github.com/univedo/api2go): A JSON API Implementation for Go
|
||
|
|
* [Gin](https://github.com/gin-gonic/gin): Features a martini-like API with much better performance
|
||
|
|
* [Goat](https://github.com/bahlo/goat): A minimalistic REST API server in Go
|
||
|
|
* [Hikaru](https://github.com/najeira/hikaru): Supports standalone and Google AppEngine
|
||
|
|
* [Hitch](https://github.com/nbio/hitch): Hitch ties httprouter, [httpcontext](https://github.com/nbio/httpcontext), and middleware up in a bow
|
||
|
|
* [kami](https://github.com/guregu/kami): A tiny web framework using x/net/context
|
||
|
|
* [Medeina](https://github.com/imdario/medeina): Inspired by Ruby's Roda and Cuba
|
||
|
|
* [Neko](https://github.com/rocwong/neko): A lightweight web application framework for Golang
|
||
|
|
* [Roxanna](https://github.com/iamthemuffinman/Roxanna): An amalgamation of httprouter, better logging, and hot reload
|
||
|
|
* [siesta](https://github.com/VividCortex/siesta): Composable HTTP handlers with contexts
|