I have the following code (just as a test) and I want to create an HTTP proxy using EventMachine. The code below is an example on the es-proxy GitHub page. However, when I run this and open up a website that has a moderate amount of images, the images start loading incorrectly. What I mean by this is that some images are loaded twice or if I request my icon for the navigation bar, I instead get the profile picture. This is especially evident if I refresh the page a few times.
It seems that the responses do not correspond to the matching request; causing everything to be jumbled. However, I'm not sure why this is. The code below seems simple enough for this to not be a problem.
require 'rubygems'
require 'em-proxy'
require 'http/parser' # gem install http_parser.rb
require 'uuid' # gem install uuid
# > ruby em-proxy-http.rb
# > curl --proxy localhost:9889 www.google.com
host = "0.0.0.0"
port = 9889
puts "listening on #{host}:#{port}..."
Proxy.start(:host => host, :port => port) do |conn|
#p = Http::Parser.new
#p.on_headers_complete = proc do |h|
session = UUID.generate
puts "New session: #{session} (#{h.inspect})"
host, port = h['Host'].split(':')
conn.server session, :host => host, :port => (port || 80)
conn.relay_to_servers #buffer
#buffer = ''
end
#buffer = ''
conn.on_connect do |data,b|
puts [:on_connect, data, b].inspect
end
conn.on_data do |data|
#buffer << data
#p << data
data
end
conn.on_response do |backend, resp|
#puts [:on_response, backend, resp].inspect
resp
end
conn.on_finish do |backend, name|
puts [:on_finish, name].inspect
end
end
Update
I believe I have insight as to what is happening but, still no way of solving my problem. I am creating a server for each request and when I relay my requests I have multiple servers. Then in the on response I should only be returning the response if it is from the correct server. However, I don't have a way to correlate this as of yet.
Here a proper response:
Try removing every puts in the example so the main loop can concentrate on doing the actual network I/O, it works for me like that.
I think there may be some kind of timeout playing behind this, maybe the client does not wait long enough for the full answer to come back while the server is stuck outputing text to the console.
That's the downside of using an event reactor, you have to make sure nothing blocks it.
The code doesn't seem to account for persistent http connections. Maybe you could try a HTTP 1.0 browser.
Related
I'm using Ruby 1.9.3 and need to GET a URL. I have this working with Net::HTTP, however, if the site is down, Net::HTTP ends up hanging.
While searching the internet, I've seen many people faced similar problems, all with hacky solutions. However, many of those posts are quite old.
Requirements:
I'd prefer using Net::HTTP to installing a new gem.
I need both the Body and the Response Code. (e.g. 200)
I do not want to require open-uri, since that makes global changes and raises some security issues.
I need to GET a URL within X seconds, or return error.
Using Ruby 1.9.3, how can I GET a URL while setting a timeout?
To clarify, my existing code looks like:
Net::HTTP.get_response(URI.parse(url))
Trying to add:
Net::HTTP.open_timeout(1000)
Results in:
NoMethodError: undefined method `open_timeout' for Net::HTTP:Class
You can set the open_timeout attribute of the Net::HTTP object before making the connection.
uri = URI.parse(url)
Net::HTTP.new(uri.hostname, uri.port) do |http|
http.open_timeout = 1000
response = http.request_get(uri.request_uri)
end
I tried all the solutions here and on the other questions about this problem but I only got everything right with the following code, The open-uri gem is a wrapper for net::http.
I needed a get that had to wait longer than the default timeout and read the response. The code is also simpler.
require 'open-uri'
open(url, :read_timeout => 5 * 60) do |response|
if response.read[/Return: Ok/i]
log "sending ok"
else
raise "error sending, no confirmation received"
end
end
I have a working Sinatra app that uses redis-namespace for its Redis connections. It works fine, but on Heroku it keeps running out of its 10 Redis connections, despite having very little traffic - they seem to stay open for ages and the app keeps opening new ones.
So, there might be a better way to structure what I've got, so it doesn't keep opening new connections. Or maybe I can use connection_pool... although I'm not sure how to use that with redis-namespace.
The Sinatra front end (myapp/frontend.rb) is something like:
require 'sinatra/base'
require 'myapp/store'
module MyApp
class Frontend < Sinatra::Base
registration_store = MyApp::Store::Registration.new
subscription_store = MyApp::Store::Subscription.new
get '/' do
...
end
...
end
end
And the Redis-accessing Store classes are in myapp/store.rb:
require 'redis'
require 'redis-namespace'
module MyApp
module Store
class RedisBase
attr_accessor :redis
def initialize
uri = URI.parse(ENV['REDISCLOUD_URL'])
redis = ::Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)
#redis = ::Redis::Namespace.new(:myapp, :redis => redis)
end
class Registration < RedisBase
def add(user_id)
redis.sadd(:registrations, user_id)
end
...
end
class Subscription < RedisBase
...
end
end
end
end
The frontend stores data via the Store classes: registration_store.add(37).
Am I doing something wrong that keeps opening new connections unnecessarily? Or, how can I add connection_pool or similar?
I bumped into a similar problem and stumbled upon this question. I think you should add redis.quit somewhere in your code. Doing some manual testing monitoring connections with client list on the redis command line gives that the connection disappears on a quit. The object can still be used later and will open a new connection it the connection is closed. No need for pooling! (At least when the load is low.... I guess you may end up with calls not getting a connection under higher loads.)
I have written a code which uses ruby threads.
require 'rubygems'
require 'net/http'
require 'uri'
def get_response()
uri = URI.parse('https://..........')
http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
-----
-----
end
t1 = []
15.times do |i|
t1[i] = Thread.new{
hit_mdm(i)
sleep(rand(0)/10.0)
}
end
t1.each {|t| t.join}
The code works fine, but when the programs reaches its end it throws following error:
ruby/2.0.0/openssl/buffering.rb:174:in `sysread_nonblock': end of file reached (EOFError)
How to overcome this problem.
def getHttp(uri)
begin
http = Net::HTTP.new(uri.host, uri.port)
rescue
p 'failed Net::HTTP.new', uri
retry
end
http
end
based on the downvoted answer, I attached some code to show an catch exception example
You haven't specified what hit_mdm() is, but presumably it's something that calls get_response considering your Net::HTTP setup prior.
There's many places on the web where you can find evidence that Net::HTTP is probably thread safe, though nothing conclusive.
I've done lots of stress testing with Net::HTTP and threads and my experience is that the EOFErrors are common problems with multiple HTTP connections. Whether it's happening because of the server or the client or the connection or the Net::HTTP library is going to be very difficult to debug, especially using threaded code which does TCP communication, which is also threaded, in a sense.
You could use wireshark to figure out where the EOFError is coming from, or, you could save yourself a lot of headache and just rescue the EOFError on the sysread (your backtrace can tell you where to put the rescue so it's only effecting the Net::HTTP call, if that's where the EOFError is generated).
But without more info, we can't really tell you why the EOFError is happening for sure.
I'm building a simple app on the side using an API I made with Sinatra that returns some JSON. It's quite a bit of JSON, my app's API relies on a few hundred requests to other APIs.
I can probably cache the results for 5 days or so, no problem with the data at all. I'm just not 100% sure how to implement the caching. How would I go about doing that with Sinatra?
Personally, I prefer to use redis for this type of things over memcached. I have an app that I use redis in pretty extensively, using it in a similar way to what you described. If I make a call that is not cached, page load time is upwards of 5 seconds, with redis, the load time drops to around 0.3 seconds. You can set an expires time as well, which can be changed quite easily. I would do something like this to retrieve the data from the cache.
require 'redis'
get '/my_data/:id' do
redis = Redis.new
if redis[params[:id]]
send_file redis[params[:id]], :type => 'application/json'
end
end
Then when you wanted to save the data to the cache, perhaps something like this:
require 'redis'
redis = Redis.new
<make API calls here and build your JSON>
redis[id] = json
redis.expire(id, 3600*24*5)
get '/my_data/:id' do
# security check for file-based caching
raise "invalid id" if params[:id] =~ /[^a-z0-9]/i
cache_file = File.join("cache",params[:id])
if !File.exist?(cache_file) || (File.mtime(cache_file) < (Time.now - 3600*24*5))
data = do_my_few_hundred_internal_requests(params[:id])
File.open(cache_file,"w"){ |f| f << data }
end
send_file cache_file, :type => 'application/json'
end
Don't forget to mkdir cache.
alternatively you could use memcache-client, but it will require you to install memcached system-wide.
I have an unordered list of links that I save off to the side, and I want to click each link and make sure it goes to a real page and doesnt 404, 500, etc.
The issue is that I do not know how to do it. Is there some object I can inspect which will give me the http status code or anything?
mylinks = Browser.ul(:id, 'my_ul_id').links
mylinks.each do |link|
link.click
# need to check for a 200 status or something here! how?
Browser.back
end
My answer is similar idea with the Tin Man's.
require 'net/http'
require 'uri'
mylinks = Browser.ul(:id, 'my_ul_id').links
mylinks.each do |link|
u = URI.parse link.href
status_code = Net::HTTP.start(u.host,u.port){|http| http.head(u.request_uri).code }
# testing with rspec
status_code.should == '200'
end
if you use Test::Unit for testing framework, you can test like the following, i think
assert_equal '200',status_code
another sample (including Chuck van der Linden's idea): check status code and log out URLs if the status is not good.
require 'net/http'
require 'uri'
mylinks = Browser.ul(:id, 'my_ul_id').links
mylinks.each do |link|
u = URI.parse link.href
status_code = Net::HTTP.start(u.host,u.port){|http| http.head(u.request_uri).code }
unless status_code == '200'
File.open('error_log.txt','a+'){|file| file.puts "#{link.href} is #{status_code}" }
end
end
There's no need to use Watir for this. A HTTP HEAD request will give you an idea whether the URL resolves and will be faster.
Ruby's Net::HTTP can do it, or you can use Open::URI.
Using Open::URI you can request a URI, and get a page back. Because you don't really care what the page contains, you can throw away that part and only return whether you got something:
require 'open-uri'
if (open('http://www.example.com').read.any?)
puts "is"
else
puts "isn't"
end
The upside is the Open::URI resolves HTTP redirects. The downside is it returns full pages so it can be slow.
Ruby's Net::HTTP can help somewhat, because it can use HTTP HEAD requests, which don't return the entire page, only a header. That by itself isn't enough to know whether the actual page is reachable because the HEAD response could redirect to a page that doesn't resolve, so you have to loop through the redirects until you either don't get a redirect, or you get an error. The Net::HTTP docs have an example to get you started:
require 'net/http'
require 'uri'
def fetch(uri_str, limit = 10)
# You should choose better exception.
raise ArgumentError, 'HTTP redirect too deep' if limit == 0
response = Net::HTTP.get_response(URI.parse(uri_str))
case response
when Net::HTTPSuccess then response
when Net::HTTPRedirection then fetch(response['location'], limit - 1)
else
response.error!
end
end
print fetch('http://www.ruby-lang.org')
Again, that example is returning pages, which might slow you down. You can replace get_response with request_head, which returns a response like get_response does, which should help.
In either case, there's another thing you have to consider. A lot of sites use "meta refreshes", which cause the browser to refresh the page, using an alternate URL, after parsing the page. Handling these requires requesting the page and parsing it, looking for the <meta http-equiv="refresh" content="5" /> tags.
Other HTTP gems like Typhoeus and Patron also can do HEAD requests easily, so take a look at them too. In particular, Typhoeus can handle some heavy loads via its companion Hydra, allowing you to easily use parallel requests.
EDIT:
require 'typhoeus'
response = Typhoeus::Request.head("http://www.example.com")
response.code # => 302
case response.code
when (200 .. 299)
#
when (300 .. 399)
headers = Hash[*response.headers.split(/[\r\n]+/).map{ |h| h.split(' ', 2) }.flatten]
puts "Redirected to: #{ headers['Location:'] }"
when (400 .. 499)
#
when (500 .. 599)
#
end
# >> Redirected to: http://www.iana.org/domains/example/
Just in case you haven't played with one, here's what the response looks like. It's useful for exactly the sort of situation you're look at:
(rdb:1) pp response
#<Typhoeus::Response:0x00000100ac3f68
#app_connect_time=0.0,
#body="",
#code=302,
#connect_time=0.055054,
#curl_error_message="No error",
#curl_return_code=0,
#effective_url="http://www.example.com",
#headers=
"HTTP/1.0 302 Found\r\nLocation: http://www.iana.org/domains/example/\r\nServer: BigIP\r\nConnection: Keep-Alive\r\nContent-Length: 0\r\n\r\n",
#http_version=nil,
#mock=false,
#name_lookup_time=0.001436,
#pretransfer_time=0.055058,
#request=
:method => :head,
:url => http://www.example.com,
:headers => {"User-Agent"=>"Typhoeus - http://github.com/dbalatero/typhoeus/tree/master"},
#requested_http_method=nil,
#requested_url=nil,
#start_time=nil,
#start_transfer_time=0.109741,
#status_message=nil,
#time=0.109822>
If you have a lot of URLs to check, see the Hydra example that is part of Typhoeus.
There's a bit of a philosophical debate on whether watir or watir-webdriver should provide HTTP return code information. The premise being that an ordinary 'user' which is what Watir is simulating on the DOM is ignorant of HTTP return codes. I don't necessarily agree with this, as I have a slightly different use case perhaps to the main (performance testing etc)... but it is what it is. This thread expresses some opinions about the distinction => http://groups.google.com/group/watir-general/browse_thread/thread/26486904e89340b7
At present there's no easy way to determine HTTP response codes from Watir without using supplementary tools like proxies/Fiddler/HTTPWatch/TCPdump, or downgrading to a net/http level of scripting mid test... I personally like using firebug with the netexport plugin to keep a retrospective look at tests.
All previous solutions are inefficient if you have a very huge number of links because for each one, it will establish a new HTTP connection with the server hosting the link.
I have written a one-liner bash command that will use the curl command to fetch a list of links supplied from stdin and returns a list of status codes corresponding to each link. The key point here is that curl takes all bunch of links in the same invocation and it will reuse HTTP connections which will dramatically improve speed.
However, curl will divide the list into chunks of 256, which is still by far more than 1! To make sure connections are reused, sort the links first (simply using the sort command).
cat <YOUR_LINKS_FILE_ONE_PER_LINE> | xargs curl --head --location -w '---HTTP_STATUS_CODE:%{http_code}\n\n' -s --retry 10 --globoff | grep HTTP_STATUS_CODE | cut -d: -f2 > <RESULTS_FILE>
It is worth noting that the above command will follow HTTP redirects, retry 10 times for temporary errors (timeouts or 5xx) and of course will only fetch headers.
Update: added --globoff so that curl won't expand any url if it contains {} or []