class Net::HTTP

Class Net::HTTP provides a rich library that implements the client in a client-server model that uses the HTTP request-response protocol. For information about HTTP, see:

About the Examples

Examples here assume that net/http has been required (which also requires uri):

require 'net/http'

Many code examples here use these example websites:

Some examples also assume these variables:

uri = URI('https://jsonplaceholder.typicode.com/')
uri.freeze # Examples may not modify.
hostname = uri.hostname # => "jsonplaceholder.typicode.com"
path = uri.path         # => "/"
port = uri.port         # => 443

So that example requests may be written as:

Net::HTTP.get(uri)
Net::HTTP.get(hostname, '/index.html')
Net::HTTP.start(hostname) do |http|
  http.get('/todos/1')
  http.get('/todos/2')
end

An example that needs a modified URI first duplicates uri, then modifies the duplicate:

_uri = uri.dup
_uri.path = '/todos/1'

Strategies

The methods cited above are convenience methods that, via their few arguments, allow minimal control over the requests. For greater control, consider using request objects.

URIs

On the internet, a URI (Universal Resource Identifier) is a string that identifies a particular resource. It consists of some or all of: scheme, hostname, path, query, and fragment; see URI syntax.

A Ruby URI::Generic object represents an internet URI. It provides, among others, methods scheme, hostname, path, query, and fragment.

Schemes

An internet URI has a scheme.

The two schemes supported in Net::HTTP are 'https' and 'http':

uri.scheme                       # => "https"
URI('http://example.com').scheme # => "http"

Hostnames

A hostname identifies a server (host) to which requests may be sent:

hostname = uri.hostname # => "jsonplaceholder.typicode.com"
Net::HTTP.start(hostname) do |http|
  # Some HTTP stuff.
end

Paths

A host-specific path identifies a resource on the host:

_uri = uri.dup
_uri.path = '/todos/1'
hostname = _uri.hostname
path = _uri.path
Net::HTTP.get(hostname, path)

Queries

A host-specific query adds name/value pairs to the URI:

_uri = uri.dup
params = {userId: 1, completed: false}
_uri.query = URI.encode_www_form(params)
_uri # => #<URI::HTTPS https://jsonplaceholder.typicode.com?userId=1&completed=false>
Net::HTTP.get(_uri)

Fragments

A URI fragment has no effect in Net::HTTP; the same data is returned, regardless of whether a fragment is included.

Request Headers

Request headers may be used to pass additional information to the host, similar to arguments passed in a method call; each header is a name/value pair.

Each of the Net::HTTP methods that sends a request to the host has optional argument headers, where the headers are expressed as a hash of field-name/value pairs:

headers = {Accept: 'application/json', Connection: 'Keep-Alive'}
Net::HTTP.get(uri, headers)

See lists of both standard request fields and common request fields at Request Fields. A host may also accept other custom fields.

HTTP Sessions

A session is a connection between a server (host) and a client that:

See example sessions at Strategies.

Session Using Net::HTTP.start

If you have many requests to make to a single host (and port), consider using singleton method Net::HTTP.start with a block; the method handles the session automatically by:

In the block, you can use these instance methods, each of which that sends a single request:

Session Using Net::HTTP.start and Net::HTTP.finish

You can manage a session manually using methods start and finish:

http = Net::HTTP.new(hostname)
http.start
http.get('/todos/1')
http.get('/todos/2')
http.delete('/posts/1')
http.finish # Needed to free resources.

Single-Request Session

Certain convenience methods automatically handle a session by:

Such methods that send GET requests:

Such methods that send POST requests:

HTTP Requests and Responses

Many of the methods above are convenience methods, each of which sends a request and returns a string without directly using Net::HTTPRequest and Net::HTTPResponse objects.

You can, however, directly create a request object, send the request, and retrieve the response object; see:

Following Redirection

Each returned response is an instance of a subclass of Net::HTTPResponse. See the response class hierarchy.

In particular, class Net::HTTPRedirection is the parent of all redirection classes. This allows you to craft a case statement to handle redirections properly:

def fetch(uri, limit = 10)
  # You should choose a better exception.
  raise ArgumentError, 'Too many HTTP redirects' if limit == 0

  res = Net::HTTP.get_response(URI(uri))
  case res
  when Net::HTTPSuccess     # Any success class.
    res
  when Net::HTTPRedirection # Any redirection class.
    location = res['Location']
    warn "Redirected to #{location}"
    fetch(location, limit - 1)
  else                      # Any other class.
    res.value
  end
end

fetch(uri)

Basic Authentication

Basic authentication is performed according to RFC2617:

req = Net::HTTP::Get.new(uri)
req.basic_auth('user', 'pass')
res = Net::HTTP.start(hostname) do |http|
  http.request(req)
end

Streaming Response Bodies

By default Net::HTTP reads an entire response into memory. If you are handling large files or wish to implement a progress bar you can instead stream the body directly to an IO.

Net::HTTP.start(hostname) do |http|
  req = Net::HTTP::Get.new(uri)
  http.request(req) do |res|
    open('t.tmp', 'w') do |f|
      res.read_body do |chunk|
        f.write chunk
      end
    end
  end
end

HTTPS

HTTPS is enabled for an HTTP connection by Net::HTTP#use_ssl=:

Net::HTTP.start(hostname, :use_ssl => true) do |http|
  req = Net::HTTP::Get.new(uri)
  res = http.request(req)
end

Or if you simply want to make a GET request, you may pass in a URI object that has an HTTPS URL. Net::HTTP automatically turns on TLS verification if the URI object has a ‘https’ URI scheme:

uri # => #<URI::HTTPS https://jsonplaceholder.typicode.com/>
Net::HTTP.get(uri)

Proxy Server

An HTTP object can have a proxy server.

You can create an HTTP object with a proxy server using method Net::HTTP.new or method Net::HTTP.start.

The proxy may be defined either by argument p_addr or by environment variable 'http_proxy'.

Proxy Using Argument p_addr as a String

When argument p_addr is a string hostname, the returned http has the given host as its proxy:

http = Net::HTTP.new(hostname, nil, 'proxy.example')
http.proxy?          # => true
http.proxy_from_env? # => false
http.proxy_address   # => "proxy.example"
# These use default values.
http.proxy_port      # => 80
http.proxy_user      # => nil
http.proxy_pass      # => nil

The port, username, and password for the proxy may also be given:

http = Net::HTTP.new(hostname, nil, 'proxy.example', 8000, 'pname', 'ppass')
# => #<Net::HTTP jsonplaceholder.typicode.com:80 open=false>
http.proxy?          # => true
http.proxy_from_env? # => false
http.proxy_address   # => "proxy.example"
http.proxy_port      # => 8000
http.proxy_user      # => "pname"
http.proxy_pass      # => "ppass"

Proxy Using ‘ENV['http_proxy']’

When environment variable 'http_proxy' is set to a URI string, the returned http will have the server at that URI as its proxy; note that the URI string must have a protocol such as 'http' or 'https':

ENV['http_proxy'] = 'http://example.com'
http = Net::HTTP.new(hostname)
http.proxy?          # => true
http.proxy_from_env? # => true
http.proxy_address   # => "example.com"
# These use default values.
http.proxy_port      # => 80
http.proxy_user      # => nil
http.proxy_pass      # => nil

The URI string may include proxy username, password, and port number:

ENV['http_proxy'] = 'http://pname:ppass@example.com:8000'
http = Net::HTTP.new(hostname)
http.proxy?          # => true
http.proxy_from_env? # => true
http.proxy_address   # => "example.com"
http.proxy_port      # => 8000
http.proxy_user      # => "pname"
http.proxy_pass      # => "ppass"

Filtering Proxies

With method Net::HTTP.new (but not Net::HTTP.start), you can use argument p_no_proxy to filter proxies:

Compression and Decompression

Net::HTTP does not compress the body of a request before sending.

By default, Net::HTTP adds header 'Accept-Encoding' to a new request object:

Net::HTTP::Get.new(uri)['Accept-Encoding']
# => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"

This requests the server to zip-encode the response body if there is one; the server is not required to do so.

Net::HTTP does not automatically decompress a response body if the response has header 'Content-Range'.

Otherwise decompression (or not) depends on the value of header Content-Encoding:

What’s Here

First, what’s elsewhere. Class Net::HTTP:

This is a categorized summary of methods and attributes.

Net::HTTP Objects

Sessions

Connections

Requests

Responses

Proxies

Security

Addresses and Ports

HTTP Version

Debugging

Attributes

response_body_encoding [R]

Returns the encoding to use for the response body; see response_body_encoding=.