violetear

README

violetear

Go HTTP router

http://violetear.org

Design Goals

• Keep it simple and small, avoiding extra complexity at all cost. KISS
• Support for static and dynamic routing.
• Easy middleware compatibility so that it satisfies the http.Handler interface.
• Common context between middleware.
• Trace Request-ID per request.
• HTTP/2 native support Push Example
• Versioning based on Accept header application/vnd.*

Package GoDoc

How it works

The router is capable off handle any kind or URI, static, dynamic or catchall and based on the HTTP request Method accept or discard the request.

For example, suppose we have an API that exposes a service that allow to ping any IP address.

To handle only "GET" request for any IPv4 addresss:

http://api.violetear.org/command/ping/127.0.0.1
                        \______/\___/\________/
                            |     |      |
                             static      |
                                      dynamic

The router HandlerFunc would be:

router.HandleFunc("/command/ping/:ip", ip_handler, "GET")

For this to work, first the regex matching :ip should be added:

router.AddRegex(":ip", `^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$`)

Now let's say you also want to be available to ping ipv6 or any host:

http://api.violetear.org/command/ping/*
                        \______/\___/\_/
                            |     |   |
                             static   |
                                   catch-all

A catch-all could be used and also a different handler, for example:

router.HandleFunc("/command/ping/*", any_handler, "GET, HEAD")

The * indicates the router to behave like a catch-all therefore it will match anything after the /command/ping/ if no other condition matches before.

Notice also the "GET, HEAD", that indicates that only does HTTP methods will be accepted, and any other will not be allowed, router will return a 405 the one can also be customised.

Usage

Requirementes go >= 1.7 (https://golang.org/pkg/context/ required)

import "github.com/nbari/violetear"

HandleFunc:

 func HandleFunc(path string, handler http.HandlerFunc, http_methods ...string)

Handle (useful for middleware):

 func Handle(path string, handler http.Handler, http_methods ...string)

http_methods is a comma separted list of allowed HTTP methods, example:

router.HandleFunc("/view", handleView, "GET, HEAD")

AddRegex adds a ":named" regular expression to the dynamicRoutes, example:

router.AddRegex(":ip", `^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$`)

Basic example:

package main

import (
    "github.com/nbari/violetear"
    "log"
    "net/http"
)

func catchAll(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("I'm catching all\n"))
}

func handleGET(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("I handle GET requests\n"))
}

func handlePOST(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("I handle POST requests\n"))
}

func handleUUID(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("I handle dynamic requests\n"))
}

func main() {
    router := violetear.New()
    router.LogRequests = true
    router.RequestID = "Request-ID"

    router.AddRegex(":uuid", `[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}`)

    router.HandleFunc("*", catchAll)
    router.HandleFunc("/method", handleGET, "GET")
    router.HandleFunc("/method", handlePOST, "POST")
    router.HandleFunc("/:uuid", handleUUID, "GET,HEAD")

    srv := &http.Server{
        Addr:           ":8080",
        Handler:        router,
        ReadTimeout:    5 * time.Second,
        WriteTimeout:   7 * time.Second,
        MaxHeaderBytes: 1 << 20,
    }
    log.Fatal(srv.ListenAndServe())

}

Running this code will show something like this:

$ go run test.go
2015/10/22 17:14:18 Adding path: * [ALL]
2015/10/22 17:14:18 Adding path: /method [GET]
2015/10/22 17:14:18 Adding path: /method [POST]
2015/10/22 17:14:18 Adding path: /:uuid [GET,HEAD]

Using router.Verbose = false will omit printing the paths.

test.go contains the code show above

Testing using curl or http

Any request 'catch-all':

$ http POST http://localhost:8080/
HTTP/1.1 200 OK
Content-Length: 17
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 15:18:49 GMT
Request-Id: POST-1445527129854964669-1

I'm catching all

A GET request:

$ http http://localhost:8080/method
HTTP/1.1 200 OK
Content-Length: 22
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 15:43:25 GMT
Request-Id: GET-1445528605902591921-1

I handle GET requests

A POST request:

$ http POST http://localhost:8080/method
HTTP/1.1 200 OK
Content-Length: 23
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 15:44:28 GMT
Request-Id: POST-1445528668557478433-2

I handle POST requests

A dynamic request using an UUID as the URL resource:

$ http http://localhost:8080/50244127-45F6-4210-A89D-FFB0DA039425
HTTP/1.1 200 OK
Content-Length: 26
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 15:45:33 GMT
Request-Id: GET-1445528733916239110-5

I handle dynamic requests

Trying to use POST on the /:uuid resource will cause a Method not Allowed 405 this because only GET and HEAD methods are allowed:

$ http POST http://localhost:8080/50244127-45F6-4210-A89D-FFB0DA039425
HTTP/1.1 405 Method Not Allowed
Content-Length: 19
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 15:47:19 GMT
Request-Id: POST-1445528839403536403-6
X-Content-Type-Options: nosniff

Method Not Allowed

RequestID

To keep track of the "requests" an existing "request ID" header can be used, if the header name for example is Request-ID therefore to continue using it, the router needs to know the name, example:

router := violetear.New()
router.RequestID = "X-Appengine-Request-Log-Id"

If the proxy is using another name, for example "RID" then use something like:

router := violetear.New()
router.RequestID = "RID"

If router.RequestID is not set, no "request ID" is going to be added to the headers. This can be extended using a middleware same has the logger check the AppEngine example.

NotFoundHandler

For defining a custom http.Handler to handle 404 Not Found example:

...

func my404() http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        http.Error(w, "ne ne ne", 404)
    })
}

func main() {
    router := violetear.New()
    router.NotFoundHandler = my404()
    ...

NotAllowedHandler

For defining a custom http.Handler to handle 405 Method Not Allowed.

PanicHandler

For using a custom http.HandlerFunc to handle panics

Middleware

Violetear uses Alice to handle middleware.

Example:

package main

import (
	"context"
	"log"
	"net/http"

	"github.com/nbari/violetear"
	"github.com/nbari/violetear/middleware"
)

func commonHeaders(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-app-Version", "1.0")
		next.ServeHTTP(w, r)
	})
}

func middlewareOne(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		log.Println("Executing middlewareOne")
		ctx := context.WithValue(r.Context(), "m1", "m1")
		ctx = context.WithValue(ctx, "key", 1)
		next.ServeHTTP(w, r.WithContext(ctx))
		log.Println("Executing middlewareOne again")
	})
}

func middlewareTwo(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		log.Println("Executing middlewareTwo")
		if r.URL.Path != "/" {
			return
		}
		ctx := context.WithValue(r.Context(), "m2", "m2")
		next.ServeHTTP(w, r.WithContext(ctx))
		log.Println("Executing middlewareTwo again")
	})
}

func catchAll(w http.ResponseWriter, r *http.Request) {
	log.Printf("Executing finalHandler\nm1:%s\nkey:%d\nm2:%s\n",
		r.Context().Value("m1"),
		r.Context().Value("key"),
		r.Context().Value("m2"),
	)
	w.Write([]byte("I catch all"))
}

func foo(w http.ResponseWriter, r *http.Request) {
	panic("this will never happen, because of the return")
}

func main() {
	router := violetear.New()

	stdChain := middleware.New(commonHeaders, middlewareOne, middlewareTwo)

	router.Handle("/", stdChain.ThenFunc(catchAll), "GET,HEAD")
	router.Handle("/foo", stdChain.ThenFunc(foo), "GET,HEAD")
	router.HandleFunc("/bar", foo)

	log.Fatal(http.ListenAndServe(":8080", router))
}

Notice the use or router.Handle and router.HandleFunc when using middleware you normally would use route.Handle

Request output example:

$ http http://localhost:8080/
HTTP/1.1 200 OK
Content-Length: 11
Content-Type: text/plain; charset=utf-8
Date: Thu, 22 Oct 2015 16:08:18 GMT
Request-Id: GET-1445530098002701428-3
X-App-Version: 1.0

I catch all

On the server you will see something like this:

$ go run test.go
2016/08/17 18:08:42 Adding path: / [GET,HEAD]
2016/08/17 18:08:42 Adding path: /foo [GET,HEAD]
2016/08/17 18:08:42 Adding path: /bar [ALL]
2016/08/17 18:08:47 Executing middlewareOne
2016/08/17 18:08:47 Executing middlewareTwo
2016/08/17 18:08:47 Executing finalHandler
m1:m1
key:1
m2:m2
2016/08/17 18:08:47 Executing middlewareTwo again
2016/08/17 18:08:47 Executing middlewareOne again

AppEngine

The app.yaml file:

application: 'app-name'
version: 1
runtime: go
api_version: go1

handlers:

- url: /.*
  script: _go_app

The app.go file:

package app

import (
    "appengine"
    "github.com/nbari/violetear"
    "github.com/nbari/violetear/middleware"
    "net/http"
)

func init() {
    router := violetear.New()
    stdChain := middleware.New(requestID)
    router.Handle("*", stdChain.ThenFunc(index), "GET, HEAD")
    http.Handle("/", router)
}

func requestID(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        c := appengine.NewContext(r)
        w.Header().Set("Request-ID", appengine.RequestID(c))
        next.ServeHTTP(w, r)
    })
}

func index(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Hello world!"))
}

Demo: http://api.violetear.org

Using curl or http:

$ http http://api.violetear.org
HTTP/1.1 200 OK
Cache-Control: private
Content-Encoding: gzip
Content-Length: 32
Content-Type: text/html; charset=utf-8
Date: Sun, 25 Oct 2015 06:14:55 GMT
Request-Id: 562c735f00ff0902f823e514a90001657e76696f6c65746561722d31313037000131000100
Server: Google Frontend

Hello world!

Context & Named parameters

In some cases there is a need to pass data across handlers/middlewares, for doing this Violetear uses net/context.

When using dynamic routes :regex, you can use GetParam or GetParams, see below.

Example:

package main

import (
    "context"
    "fmt"
    "log"
    "net/http"

    "github.com/nbari/violetear"
)

func catchAll(w http.ResponseWriter, r *http.Request) {
    // Get & print the content of named-param *
    params := r.Context().Value(violetear.ParamsKey).(violetear.Params)
    fmt.Fprintf(w, "CatchAll value:, %q", params["*"])
}

func handleUUID(w http.ResponseWriter, r *http.Request) {
    // get router params
    params := r.Context().Value(violetear.ParamsKey).(violetear.Params)
    // using GetParam
    uuid := violetear.GetParam("uuid", r)
    // add a key-value pair to the context
    ctx := context.WithValue(r.Context(), "key", "my-value")
    // print current value for :uuid
    fmt.Fprintf(w, "Named parameter: %q, uuid; %q,  key: %s",
        params[":uuid"],
        uuid,
        ctx.Value("key"),
    )
}

func main() {
    router := violetear.New()

    router.AddRegex(":uuid", `[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}`)

    router.HandleFunc("*", catchAll)
    router.HandleFunc("/:uuid", handleUUID, "GET,HEAD")

    srv := &http.Server{
        Addr:           ":8080",
        Handler:        router,
        ReadTimeout:    5 * time.Second,
        WriteTimeout:   7 * time.Second,
        MaxHeaderBytes: 1 << 20,
    }
    log.Fatal(srv.ListenAndServe())
}

Duplicated named parameters

In cases where the same named parameter is used multiple times, example:

/test/:uuid/:uuid/

An slice is created, for getting the values you need to do something like:

params := r.Context().Value(violetear.ParamsKey).(violetear.Params)
uuid := params[":uuid"].([]string)

Notice the : prefix when getting the named_parameters

Or by using GetParams:

uuid := violetear.GetParams("uuid")

After this you can access the slice like normal:

fmt.Println(uuid[0], uuid[1])

Documentation

Overview

Package violetear - HTTP router

Basic example:

package main

import (
   "fmt"
   "github.com/nbari/violetear"
   "log"
   "net/http"
)

func catchAll(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, r.URL.Path[1:])
}

func helloWorld(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, r.URL.Path[1:])
}

func handleUUID(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, r.URL.Path[1:])
}

func main() {
    router := violetear.New()
    router.LogRequests = true
    router.RequestID = "REQUEST_LOG_ID"

    router.AddRegex(":uuid", `[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}`)

    router.HandleFunc("*", catchAll)
    router.HandleFunc("/hello", helloWorld, "GET,HEAD")
    router.HandleFunc("/root/:uuid/item", handleUUID, "POST,PUT")

    srv := &http.Server{
        Addr:           ":8080",
        Handler:        router,
        ReadTimeout:    5 * time.Second,
        WriteTimeout:   7 * time.Second,
        MaxHeaderBytes: 1 << 20,
    }
    log.Fatal(srv.ListenAndServe())
}

Index

• Constants
• func GetParam(name string, r *http.Request, index ...int) string
• func GetParams(name string, r *http.Request) []string
• func GetRouteName(r *http.Request) string
• type MethodHandler
• type Params
  • func (p Params) Add(k, v string)
• type ResponseWriter
  • func NewResponseWriter(w http.ResponseWriter, rid string) *ResponseWriter
  • func (w *ResponseWriter) RequestID() string
  • func (w *ResponseWriter) RequestTime() string
  • func (w *ResponseWriter) Size() int
  • func (w *ResponseWriter) Status() int
  • func (w *ResponseWriter) Write(data []byte) (int, error)
  • func (w *ResponseWriter) WriteHeader(statusCode int)
• type Router
  • func New() *Router
  • func (r *Router) AddRegex(name, regex string) error
  • func (r *Router) GetError() error
  • func (r *Router) Handle(path string, handler http.Handler, httpMethods ...string) *Trie
  • func (r *Router) HandleFunc(path string, handler http.HandlerFunc, httpMethods ...string) *Trie
  • func (r *Router) MethodNotAllowed() http.HandlerFunc
  • func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request)
• type Trie
  • func (t *Trie) Get(path, version string) (*Trie, string, string, bool)
  • func (t *Trie) Name(name string) *Trie
  • func (t *Trie) Set(path []string, handler http.Handler, method, version string) (*Trie, error)
  • func (t *Trie) SplitPath(path string) (string, string)

Constants

const (
	ParamsKey key = 0
)

ParamsKey used for the context

Functions

func GetParam

func GetParam(name string, r *http.Request, index ...int) string

GetParam returns a value for the parameter set in path When having duplicate params pass the index as the last argument to retrieve the desired value.

func GetParams

func GetParams(name string, r *http.Request) []string

GetParams returns param or params in a []string

func GetRouteName

func GetRouteName(r *http.Request) string

GetRouteName return the name of the route

Types

type MethodHandler

type MethodHandler struct {
	Method  string
	Handler http.Handler
}

MethodHandler keeps HTTP Method and http.handler

type Params

type Params map[string]interface{}

Params string/interface map used with context

func (Params) Add

func (p Params) Add(k, v string)

Add param to Params

type ResponseWriter

type ResponseWriter struct {
	http.ResponseWriter
	// contains filtered or unexported fields
}

ResponseWriter wraps the standard http.ResponseWriter

func NewResponseWriter

func NewResponseWriter(w http.ResponseWriter, rid string) *ResponseWriter

NewResponseWriter returns ResponseWriter

func (*ResponseWriter) RequestID

func (w *ResponseWriter) RequestID() string

RequestID retrieve the Request ID

func (*ResponseWriter) RequestTime

func (w *ResponseWriter) RequestTime() string

RequestTime return the request time

func (*ResponseWriter) Size

func (w *ResponseWriter) Size() int

Size provides an easy way to retrieve the response size in bytes

func (*ResponseWriter) Status

func (w *ResponseWriter) Status() int

Status provides an easy way to retrieve the status code

func (*ResponseWriter) Write

func (w *ResponseWriter) Write(data []byte) (int, error)

Write satisfies the http.ResponseWriter interface and captures data written, in bytes

func (*ResponseWriter) WriteHeader

func (w *ResponseWriter) WriteHeader(statusCode int)

WriteHeader satisfies the http.ResponseWriter interface and allows us to catch the status code

type Router

type Router struct {

	// Logger
	Logger func(*ResponseWriter, *http.Request)

	// LogRequests yes or no
	LogRequests bool

	// NotFoundHandler configurable http.Handler which is called when no matching
	// route is found. If it is not set, http.NotFound is used.
	NotFoundHandler http.Handler

	// NotAllowedHandler configurable http.Handler which is called when method not allowed.
	NotAllowedHandler http.Handler

	// PanicHandler function to handle panics.
	PanicHandler http.HandlerFunc

	// RequestID name of the header to use or create.
	RequestID string

	// Verbose
	Verbose bool
	// contains filtered or unexported fields
}

Router struct

func New

func New() *Router

New returns a new initialized router.

func (*Router) AddRegex

func (r *Router) AddRegex(name, regex string) error

AddRegex adds a ":named" regular expression to the dynamicRoutes

func (*Router) GetError

func (r *Router) GetError() error

GetError returns an error resulted from building a route, if any.

func (*Router) Handle

func (r *Router) Handle(path string, handler http.Handler, httpMethods ...string) *Trie

Handle registers the handler for the given pattern (path, http.Handler, methods).

func (*Router) HandleFunc

func (r *Router) HandleFunc(path string, handler http.HandlerFunc, httpMethods ...string) *Trie

HandleFunc add a route to the router (path, http.HandlerFunc, methods)

func (*Router) MethodNotAllowed

func (r *Router) MethodNotAllowed() http.HandlerFunc

MethodNotAllowed default handler for 405

func (*Router) ServeHTTP

func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request)

ServeHTTP dispatches the handler registered in the matched path

type Trie

type Trie struct {
	Handler     []MethodHandler
	HasCatchall bool
	HasRegex    bool
	Node        []*Trie
	// contains filtered or unexported fields
}

Trie data structure

func (*Trie) Get

func (t *Trie) Get(path, version string) (*Trie, string, string, bool)

Get returns a node

func (*Trie) Name

func (t *Trie) Name(name string) *Trie

Name add custom name to node

func (*Trie) Set

func (t *Trie) Set(path []string, handler http.Handler, method, version string) (*Trie, error)

Set adds a node (url part) to the Trie

func (*Trie) SplitPath

func (t *Trie) SplitPath(path string) (string, string)

SplitPath returns first element of path and remaining path