class HTTP::Server

Overview

A concurrent HTTP server implementation.

A server is initialized with a handler chain responsible for processing each incoming request.

require "http/server"

server = HTTP::Server.new do |context|
  context.response.content_type = "text/plain"
  context.response.print "Hello world!"
end

address = server.bind_tcp 8080
puts "Listening on http://#{address}"
server.listen

Request processing

The handler chain receives an instance of HTTP::Server::Context that holds the HTTP::Request to process and a HTTP::Server::Response which it can configure and write to.

Each connection is processed concurrently in a separate Fiber and can handle multiple subsequent requests-response cycles with connection keep-alive.

Handler chain

The handler given to a server can simply be a block that receives an HTTP::Server::Context, or it can be an instance of HTTP::Handler. An HTTP::Handler has a #next method to forward processing to the next handler in the chain.

For example, an initial handler might handle exceptions raised from subsequent handlers and return a 500 Server Error status (see HTTP::ErrorHandler). The next handler might log all incoming requests (see HTTP::LogHandler). And the final handler deals with routing and application logic.

require "http/server"

server = HTTP::Server.new([
  HTTP::ErrorHandler.new,
  HTTP::LogHandler.new,
  HTTP::CompressHandler.new,
  HTTP::StaticFileHandler.new("."),
])

server.bind_tcp "127.0.0.1", 8080
server.listen

Response object

The HTTP::Server::Response object has status and headers properties that can be configured before writing the response body. Once any response output has been written, changing the status and headers properties has no effect.

The HTTP::Server::Response is a write-only IO, so all IO methods are available on it for sending the response body.

Binding to sockets

The server can be bound to one ore more server sockets (see #bind)

Supported types:

#bind(uri : URI) and #bind(uri : String) parse socket configuration for one of these types from an URI. This can be useful for injecting plain text configuration values.

Each of these methods returns the Socket::Address that was added to this server.

require "http/server"

server = HTTP::Server.new do |context|
  context.response.content_type = "text/plain"
  context.response.print "Hello world!"
end

address = server.bind_tcp "0.0.0.0", 8080
puts "Listening on http://#{address}"
server.listen

It is also possible to bind a generic Socket::Server using #bind(socket : Socket::Server) which can be used for custom network protocol configurations.

Server loop

After defining all server sockets to listen to, the server can be started by calling #listen. This call blocks until the server is closed.

A server can be closed by calling #close. This closes the server sockets and stops processing any new requests, even on connections with keep-alive enabled. Currently processing requests are not interrupted but also not waited for. In order to give them some grace period for finishing, the calling context can add a timeout like sleep 10.seconds after #listen returns.

Reusing connections

The request processor supports reusing a connection for subsequent requests. This is used by default for HTTP/1.1 or when requested by the Connection: keep-alive header. This is signalled by this header being set on the HTTP::Server::Response when it's passed into the handler chain.

If in the handler chain this header is overridden to Connection: close, then the connection will not be reused after the request has been processed.

Reusing the connection also requires that the request body (if present) is entirely consumed in the handler chain. Otherwise the connection will be closed.

Defined in:

http/server/context.cr
http/server/response.cr
http/server.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from class Reference

==(other : self)
==(other : JSON::Any)
==(other : YAML::Any)
==(other)
==
, dup dup, hash(hasher) hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference)
same?(other : Nil)
same?
, to_s(io : IO) : Nil to_s

Constructor methods inherited from class Reference

new new

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other)
===
, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash
hash(hasher)
hash
, inspect(io : IO) : Nil
inspect : String
inspect
, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO)
to_json
to_json
, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ")
to_pretty_json
, to_s : String
to_s(io : IO) : Nil
to_s
, to_yaml(io : IO)
to_yaml
to_yaml
, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Constructor methods inherited from class Object

from_json(string_or_io, root : String) : self
from_json(string_or_io) : self
from_json
, from_yaml(string_or_io : String | IO) : self from_yaml

Constructor Detail

def self.new(handlers : Array(HTTP::Handler), &handler : HTTP::Handler::HandlerProc) : self #

Creates a new HTTP server with a handler chain constructed from the handlers array and the given block.


[View source]
def self.new(&handler : HTTP::Handler::HandlerProc) : self #

Creates a new HTTP server with the given block as handler.


[View source]
def self.new(handlers : Array(HTTP::Handler)) : self #

Creates a new HTTP server with the handlers array as handler chain.


[View source]
def self.new(handler : HTTP::Handler | HTTP::Handler::HandlerProc) #

Creates a new HTTP server with the given handler.


[View source]

Class Method Detail

def self.build_middleware(handlers, last_handler : Context -> ? = nil) #

Builds all handlers as the middleware for HTTP::Server.


[View source]

Instance Method Detail

def addresses : Array(Socket::Address) #

[View source]
def bind(socket : Socket::Server) : Nil #

Adds a Socket::Server socket to this server.


[View source]
def bind(uri : URI) : Socket::Address #

Parses a socket configuration from uri and adds it to this server. Returns the effective address it is bound to.

require "http/server"

server = HTTP::Server.new { }
server.bind("tcp://localhost:80")                                                  # => Socket::IPAddress.new("127.0.0.1", 8080)
server.bind("unix:///tmp/server.sock")                                             # => Socket::UNIXAddress.new("/tmp/server.sock")
server.bind("tls://127.0.0.1:443?key=private.key&cert=certificate.cert&ca=ca.crt") # => Socket::IPAddress.new("127.0.0.1", 443)

[View source]
def bind(uri : String) : Socket::Address #

Parses a socket configuration from uri and adds it to this server. Returns the effective address it is bound to.

require "http/server"

server = HTTP::Server.new { }
server.bind("tcp://localhost:80")                                                  # => Socket::IPAddress.new("127.0.0.1", 8080)
server.bind("unix:///tmp/server.sock")                                             # => Socket::UNIXAddress.new("/tmp/server.sock")
server.bind("tls://127.0.0.1:443?key=private.key&cert=certificate.cert&ca=ca.crt") # => Socket::IPAddress.new("127.0.0.1", 443)

[View source]
def bind_tcp(host : String, port : Int32, reuse_port : Bool = false) : Socket::IPAddress #

Creates a TCPServer listening on host:port and adds it as a socket, returning the local address and port the server listens on.

require "http/server"

server = HTTP::Server.new { }
server.bind_tcp("127.0.0.100", 8080) # => Socket::IPAddress.new("127.0.0.100", 8080)

If reuse_port is true, it enables the SO_REUSEPORT socket option, which allows multiple processes to bind to the same port.


[View source]
def bind_tcp(port : Int32, reuse_port : Bool = false) : Socket::IPAddress #

Creates a TCPServer listening on 127.0.0.1:port and adds it as a socket, returning the local address and port the server listens on.

require "http/server"

server = HTTP::Server.new { }
server.bind_tcp(8080) # => Socket::IPAddress.new("127.0.0.1", 8080)

If reuse_port is true, it enables the SO_REUSEPORT socket option, which allows multiple processes to bind to the same port.


[View source]
def bind_tcp(address : Socket::IPAddress, reuse_port : Bool = false) : Socket::IPAddress #

Creates a TCPServer listening on address and adds it as a socket, returning the local address and port the server listens on.

require "http/server"

server = HTTP::Server.new { }
server.bind_tcp(Socket::IPAddress.new("127.0.0.100", 8080)) # => Socket::IPAddress.new("127.0.0.100", 8080)
server.bind_tcp(Socket::IPAddress.new("127.0.0.100", 0))    # => Socket::IPAddress.new("127.0.0.100", 35487)

If reuse_port is true, it enables the SO_REUSEPORT socket option, which allows multiple processes to bind to the same port.


[View source]
def bind_tls(host : String, port : Int32, context : OpenSSL::SSL::Context::Server, reuse_port : Bool = false) : Socket::IPAddress #

Creates an OpenSSL::SSL::Server and adds it as a socket.

The SSL server wraps a TCPServer listening on host:port.

require "http/server"

server = HTTP::Server.new { }
context = OpenSSL::SSL::Context::Server.new
context.certificate_chain = "openssl.crt"
context.private_key = "openssl.key"
server.bind_tls "127.0.0.1", 8080, context

[View source]

Creates an OpenSSL::SSL::Server and adds it as a socket.

The SSL server wraps a TCPServer listening on an unused port on host.

require "http/server"

server = HTTP::Server.new { }
context = OpenSSL::SSL::Context::Server.new
context.certificate_chain = "openssl.crt"
context.private_key = "openssl.key"
address = server.bind_tls Socket::IPAddress.new("127.0.0.1", 8000), context

[View source]
def bind_tls(host : String, context : OpenSSL::SSL::Context::Server) : Socket::IPAddress #

Creates an OpenSSL::SSL::Server and adds it as a socket.

The SSL server wraps a TCPServer listening on an unused port on host.

require "http/server"

server = HTTP::Server.new { }
context = OpenSSL::SSL::Context::Server.new
context.certificate_chain = "openssl.crt"
context.private_key = "openssl.key"
address = server.bind_tls "127.0.0.1", context

[View source]
def bind_unix(path : String) : Socket::UNIXAddress #

Creates a UNIXServer bound to path and adds it as a socket.

require "http/server"

server = HTTP::Server.new { }
server.bind_unix "/tmp/my-socket.sock"

[View source]
def bind_unix(address : Socket::UNIXAddress) : Socket::UNIXAddress #

Creates a UNIXServer bound to address and adds it as a socket.

require "http/server"

server = HTTP::Server.new { }
server.bind_unix(Socket::UNIXAddress.new("/tmp/my-socket.sock"))

[View source]
def bind_unused_port(host : String = Socket::IPAddress::LOOPBACK, reuse_port : Bool = false) : Socket::IPAddress #

Creates a TCPServer listening on an unused port and adds it as a socket.

Returns the Socket::IPAddress with the determined port number.

require "http/server"

server = HTTP::Server.new { }
server.bind_unused_port # => Socket::IPAddress.new("127.0.0.1", 12345)

[View source]
def close #

Gracefully terminates the server. It will process currently accepted requests, but it won't accept new connections.


[View source]
def closed? : Bool #

Returns true if this server is closed.


[View source]
def each_address(&block : Socket::Address -> ) #

Enumerates all addresses this server is bound to.


[View source]
def listen(port : Int32, reuse_port : Bool = false) #

Creates a TCPServer listening on 127.0.0.1:port, adds it as a socket and starts the server. Blocks until the server is closed.

See #bind(port : Int32) for details.


[View source]
def listen(host : String, port : Int32, reuse_port : Bool = false) #

Creates a TCPServer listening on host:port, adds it as a socket and starts the server. Blocks until the server is closed.

See #bind(host : String, port : Int32) for details.


[View source]
def listen #

Starts the server. Blocks until the server is closed.


[View source]
def listening? : Bool #

Returns true if this server is listening on its sockets.


[View source]
def max_headers_size : Int32 #

Returns the maximum permitted combined size for the headers in an HTTP request.

When parsing a request, the server keeps track of the amount of total bytes consumed for all headers (including line breaks). If combined byte size of all headers is larger than the permitted size, the server responds with the status code 432 Request Header Fields Too Large (see HTTP::Status::REQUEST_HEADER_FIELDS_TOO_LARGE).

Default: HTTP::MAX_HEADERS_SIZE


[View source]
def max_headers_size=(size : Int32) #

Sets the maximum permitted combined size for the headers in an HTTP request.


[View source]
def max_request_line_size : Int32 #

Returns the maximum permitted size for the request line in an HTTP request.

The request line is the first line of a request, consisting of method, resource and HTTP version and the delimiting line break. If the request line has a larger byte size than the permitted size, the server responds with the status code 414 URI Too Long (see HTTP::Status::URI_TOO_LONG).

Default: HTTP::MAX_REQUEST_LINE_SIZE


[View source]
def max_request_line_size=(size : Int32) #

Sets the maximum permitted size for the request line in an HTTP request.


[View source]