manners

package module
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 Go to latest Published: Nov 16, 2016 License: MIT Imports: 14 Imported by: 0

README

Manners

A polite webserver for Go.

Manners allows you to shut your Go webserver down gracefully, without dropping any requests. It can act as a drop-in replacement for the standard library's http.ListenAndServe function:

func main() {
  handler := MyHTTPHandler()
  manners.ListenAndServe(":7000", handler)
}

Then, when you want to shut the server down:

manners.Close()

(Note that this does not block until all the requests are finished. Rather, the call to manners.ListenAndServe will stop blocking when all the requests are finished.)

Manners ensures that all requests are served by incrementing a WaitGroup when a request comes in and decrementing it when the request finishes.

If your request handler spawns Goroutines that are not guaranteed to finish with the request, you can ensure they are also completed with the StartRoutine and FinishRoutine functions on the server.

HTTP, HTTPS and FCGI

Manners supports three protocols: HTTP, HTTPS and FCGI. HTTP is illustrated above. For HTTPS, Manners can likewise act as a drop-in replacement for the standard library's http.ListenAndServeTLS function:

func main() {
  handler  := MyHTTPHandler()
  certFile := MyCertificate()
  keyFile  := MyKeyFile()
  manners.ListenAndServeTLS(":https", certFile, keyFile, handler)
}

In Manners, FCGI only operates via local a Unix socket connected to a co-hosted proxy, such as Apache or Nginx.

func main() {
  handler := MyHTTPHandler()
  manners.ListenAndServe("/var/run/goserver.sock", handler)
}

To use FCGI, the port string must specify the Unix socket and start with a slash or dot, as in the example above. In this case, Manners will use fcgi.Serve.

In each of the protocols, Manners drains down the connections cleanly when manners.Close() is called.

Handling signals

It's good to close down the server cleanly when OS signals are received. This is easy: just add

manners.CloseOnInterrupt()

before the ListenAndServe call. This kicks off a separate goroutine to wait for an OS signal, upon which it simply calls manners.Close() for you. Optionally, you can pass in a list of the particular signals you care about and you can find out which signal was received, if any, afterwards.

Known Issues

Manners does not correctly shut down long-lived keepalive connections when issued a shutdown command. Clients on an idle keepalive connection may see a connection reset error rather than a close. See https://github.com/braintree/manners/issues/13 for details.

Compatability

Manners 0.3.0 and above uses standard library functionality introduced in Go 1.3.

Installation

go get github.com/braintree/manners

Documentation

Overview

Package manners provides a wrapper for a standard net/http server that ensures all active HTTP client have completed their current request before the server shuts down.

It can be used a drop-in replacement for the standard http package, or can wrap a pre-configured Server.

eg. 

http.Handle("/hello", func(w http.ResponseWriter, r *http.Request) {
  w.Write([]byte("Hello\n"))
})

log.Fatal(manners.ListenAndServe(":8080", nil))

or for a customized server: 

s := manners.NewWithServer(&http.Server{
	Addr:           ":8080",
	Handler:        myHandler,
	ReadTimeout:    10 * time.Second,
	WriteTimeout:   10 * time.Second,
	MaxHeaderBytes: 1 << 20,
})
log.Fatal(s.ListenAndServe())

The server will shut down cleanly when the Close() method is called: 

manners.CloseOnInterrupt()
http.Handle("/hello", myHandler)
log.Fatal(manners.ListenAndServe(":8080", nil))

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Close 

func Close() bool

Shuts down the default server used by ListenAndServe, ListenAndServeTLS and Serve. It returns true if it's the first time Close is called.

func CloseOnInterrupt 

func CloseOnInterrupt(signals ...os.Signal)

CloseOnInterrupt creates a go-routine that will call the Close() function when certain OS signals are received. If no signals are specified, the following are used: SIGINT, SIGTERM, SIGKILL, SIGQUIT, SIGHUP, SIGUSR1. This function must be called before ListenAndServe, ListenAndServeTLS, or Serve.

func ListenAndServe 

func ListenAndServe(addr string, handler http.Handler) error

ListenAndServe provides a graceful version of the function provided by the net/http package. Call Close() to stop the server.

func ListenAndServeTLS 

func ListenAndServeTLS(addr string, certFile string, keyFile string, handler http.Handler) error

ListenAndServeTLS provides a graceful version of the function provided by the net/http package. Call Close() to stop the server.

func NewTLSListener 

func NewTLSListener(inner net.Listener, config *tls.Config) net.Listener

NewListener creates a Listener which accepts connections from an inner Listener and wraps each connection with Server. The configuration config must be non-nil and must have at least one certificate.

func Serve 

func Serve(l net.Listener, handler http.Handler) error

Serve provides a graceful version of the function provided by the net/http package. Call Close() to stop the server.

func SetLogger 

func SetLogger(l *log.Logger)

SetLogger changes the logger used for the startup and shutdown messages generated by Manners. By default, no log messages are emitted. To make Manners logging behave the same as per the standard log package, i.e. to stderr, use `SetLogger(log.New(os.Stderr, "", log.LstdFlags))`

func SignalReceived 

func SignalReceived() os.Signal

After a signal has cause the server to close, this method allows you to determine which signal had been received. If Close was called some other way, this method will return nil.

Note that, by convention, SIGUSR1 is often used to cause a server to close all its current connections cleanly, close its log files, and then restart. This facilitates log rotation. If you need this behaviour, you will need to provide a loop around the CloseOnInterrupt and ListenAndServe calls.

Types

type GracefulListener 

type GracefulListener struct {
	// contains filtered or unexported fields
}

A GracefulListener differs from a standard net.Listener in one way: if Accept() is called after it is gracefully closed, it returns a listenerAlreadyClosed error. The GracefulServer will ignore this error.

func NewListener 

func NewListener(l net.Listener) *GracefulListener

NewListener wraps an existing listener for use with GracefulServer.

Note that you generally don't need to use this directly as GracefulServer will automatically wrap any non-graceful listeners supplied to it.

func (*GracefulListener) Accept 

func (l *GracefulListener) Accept() (net.Conn, error)

Accept implements the Accept method in the Listener interface.

func (*GracefulListener) Addr 

func (l *GracefulListener) Addr() net.Addr

func (*GracefulListener) Clone 

func (l *GracefulListener) Clone() (net.Listener, error)

func (*GracefulListener) Close 

func (l *GracefulListener) Close() error

Close tells the wrapped listener to stop listening. It is idempotent.

func (*GracefulListener) GetFile 

func (l *GracefulListener) GetFile() (*os.File, error)

type GracefulServer 

type GracefulServer struct {
	*http.Server
	// contains filtered or unexported fields
}

A GracefulServer maintains a WaitGroup that counts how many in-flight requests the server is handling. When it receives a shutdown signal, it stops accepting new requests but does not actually shut down until all in-flight requests terminate.

GracefulServer embeds the underlying net/http.Server making its non-override methods and properties avaiable.

It must be initialized by calling NewServer or NewWithServer

func NewServer 

func NewServer() *GracefulServer

NewServer creates a new GracefulServer.

func NewWithOptions 

func NewWithOptions(o Options) *GracefulServer

func NewWithServer 

func NewWithServer(s *http.Server) *GracefulServer

NewWithServer wraps an existing http.Server object and returns a GracefulServer that supports all of the original Server operations.

func (*GracefulServer) BlockingClose 

func (s *GracefulServer) BlockingClose() bool

BlockingClose is similar to Close, except that it blocks until the last connection has been closed.

func (*GracefulServer) Close 

func (s *GracefulServer) Close() bool

Close stops the server from accepting new requets and begins shutting down. It returns true if it's the first time Close is called.

func (*GracefulServer) CloseOnInterrupt 

func (s *GracefulServer) CloseOnInterrupt(signals ...os.Signal) *GracefulServer

CloseOnInterrupt creates a go-routine that will call the Close() function when certain OS signals are received. If no signals are specified, the following are used: SIGINT, SIGTERM, SIGKILL, SIGQUIT, SIGHUP, SIGUSR1. This function must be called before ListenAndServe, ListenAndServeTLS, or Serve.

func (*GracefulServer) FinishRoutine 

func (s *GracefulServer) FinishRoutine()

FinishRoutine decrements the server's WaitGroup. Use this to complement StartRoutine().

func (*GracefulServer) GetFile 

func (gs *GracefulServer) GetFile() (*os.File, error)

func (*GracefulServer) HijackListener 

func (gs *GracefulServer) HijackListener(s *http.Server, config *tls.Config) (*GracefulServer, error)

func (*GracefulServer) ListenAndServe 

func (s *GracefulServer) ListenAndServe() error

ListenAndServe provides a graceful equivalent of net/http.Serve.ListenAndServe.

func (*GracefulServer) ListenAndServeTLS 

func (s *GracefulServer) ListenAndServeTLS(certFile, keyFile string) error

ListenAndServeTLS provides a graceful equivalent of net/http.Serve.ListenAndServeTLS.

func (*GracefulServer) ListenAndServeTLSWithConfig 

func (s *GracefulServer) ListenAndServeTLSWithConfig(config *tls.Config) error

ListenAndServeTLSWithConfig provides a graceful equivalent of net/http.Serve.ListenAndServeTLS using a bespoke TLS config.

func (*GracefulServer) Serve 

func (s *GracefulServer) Serve(listener net.Listener) error

Serve provides a graceful equivalent net/http.Server.Serve.

If listener is not an instance of *GracefulListener it will be wrapped to become one.

func (*GracefulServer) SignalReceived 

func (s *GracefulServer) SignalReceived() os.Signal

SignalReceived gets the signal that caused the server to close, if any. If Close() was called some other way, this method will return nil.

Note that, by convention, SIGUSR1 is often used to cause a server to close all its current connections cleanly, close its log files, and then restart. This facilitates log rotation. If you need this behaviour, you will need to provide a loop around both the CloseOnInterrupt and ListenAndServe calls.

func (*GracefulServer) StartRoutine 

func (s *GracefulServer) StartRoutine()

StartRoutine increments the server's WaitGroup. Use this if a web request starts more goroutines and these goroutines are not guaranteed to finish before the request.

type Options 

type Options struct {
	Server       *http.Server
	StateHandler StateHandler
	Listener     net.Listener
}

type StateHandler 

type StateHandler func(net.Conn, http.ConnState, http.ConnState)

StateHandler can be called by the server if the state of the connection changes. Notice that it passed previous state and the new state as parameters.

type TCPKeepAliveListener 

type TCPKeepAliveListener struct {
	*net.TCPListener
}

TCPKeepAliveListener sets TCP keep-alive timeouts on accepted connections. It's used by ListenAndServe and ListenAndServeTLS so dead TCP connections (e.g. closing laptop mid-download) eventually go away.

direct lift from net/http/server.go

func (TCPKeepAliveListener) Accept 

func (ln TCPKeepAliveListener) Accept() (c net.Conn, err error)

type TLSListener 

type TLSListener struct {
	net.Listener
	// contains filtered or unexported fields
}

A listener implements a network listener (net.Listener) for TLS connections. direct lift from crypto/tls.go

func (*TLSListener) Accept 

func (l *TLSListener) Accept() (c net.Conn, err error)

Accept waits for and returns the next incoming TLS connection. The returned connection c is a *tls.Conn.

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