Varnish your application - Make it fly!

Transcript

1. VARNISH YOUR APPLICATION Make it fly!

2. WHO AM I • Alistair Stead - @alistairstead • Technical

   Team Lead @ Ibuildings UK • Over 12 years commercial experience developing in PHP and other technologies. • http://joind.in/3591

3. PERFORMANCE AND SCALABILITY Is a hot topic for clients and

   developers alike.

4. PERFORMANCE Vs CONVERSION RATE These are directly linked!

5. PERCEIVED PERFORMANCE Vs PHYSICAL PERFORMANCE Is there an easy route

   to performance?

6. VARNISH http://www.varnish-cache.org/

7. PRELIMINARY LOAD TESTS What can Varnish do for us?

8. +4,000,000 Requests per hour

9. REVERSE PROXY? Yeah okay... tell me more!

10. CACHING PROXY? It is...

11. LOAD BALANCER? It can do that too!

12. HTTP ACCELERATOR It may just be magic!

13. WHERE TO APPLY VARNISH Apply thinly over your apache cluster

    Client Browser Varnish Port 80 Backend Apache Port 8080 Backend Apache Port 8080 Client Browser Client Browser

14. INSTALLATION Packages available for most platforms http://bit.ly/pPB7x5

15. "WITH GREAT POWER COMES GREAT RESPONSIBILITY"

16. HOW TO CONTROL CACHING Additional caching layers need to be

    coordinated

17. RFC 2616 HTTP 1.1 http://bit.ly/pLtSl0 http://bit.ly/oORXf3

18. HTTP 1.1 $ curl -I magentocommerce.com

19. HTTP/1.1 200 OK Server: nginx Date: Sun, 05 Jun 2011

    17:40:56 GMT Content-Type: text/html; charset=UTF-8 Connection: keep-alive X-Powered-By: PHP/5.2.17 Set-Cookie: PHPSESSID=j1cdbj2617abbl8ccsbkd2mt44; path=/ Expires: Mon, 26 Jul 1997 05:00:00 GMT Cache-Control: no-store, no-cache, must- revalidate, post-check=0, pre-check=0 Pragma: no-cache Last-Modified: Sun, 05 Jun 2011 17:40:56 GMT $ curl -I magentocommerce.com

20. HTTP 1.1 HEADERS Request modifiers / Response parameters

21. CACHEING WITH HTTP 1.1 Has two models Expiration & Validation

22. EXPIRATION MODEL How long may I use this resource for?

23. EXPIRATION HEADERS • Cache-Control • Expires

24. VALIDATION MODEL Is this resource still okay to use?

25. VALIDATION HEADERS • Last-Modified • If-Modified-Since • ETag • If-None-Match

26. HTTP CACHE HEADERS Should only work with safe HTTP verbs

    GET & HEAD

27. HTTP 1.1 REQUEST FLOW

28. Client Application Client Cache GET / HTTP1.1 Host: mystore.com GET

    / HTTP1.1 Host: mystore.com HTTP1.1 200 OK HTTP1.1 200 OK

29. Client Application Client Cache GET / HTTP1.1 Host: mystore.com GET

    / HTTP1.1 Host: mystore.com HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max-age=20

30. Client Application Client Cache GET / HTTP1.1 Host: mystore.com HTTP1.1

    200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max-age=20

31. Client Application Client Cache GET / HTTP1.1 Host: mystore.com GET

    / HTTP1.1 Host: mystore.com HTTP1.1 200 OK Etag: abcde HTTP1.1 200 OK Etag: abcde HTTP1.1 200 OK Etag: abcde

32. Client Application Client Cache GET / HTTP1.1 Host: mystore.com GET

    / HTTP1.1 Host: mystore.com If-None-Match: abcde HTTP1.1 304 Not Modified HTTP1.1 304 Not Modified HTTP1.1 200 OK Etag: abcde

33. EXPIRATION ALLOWS YOU TO SCALE VALIDATION SAVES BANDWIDTH Fewer requests

    hitting your server and client speed is better too!

34. OUR GOAL IS TO NEVER GENERATE THE SAME RESPONSE TWICE

35. LEVERAGE HTTP CACHE IN MAGENTO With an event observer this

    is simple.

36. <?php class Disclosure_Varnish_Model_Observer extends Disclosure_Varnish_Model_Observer_Abstract { /** * Update the

    headers transmitted to allow greater varnish cache hits * * @param $observer */ public function processPreDispatch(Varien_Event_Observer $observer) { if (!$this->isVarnishEnabled()) { return $this; } $routeTtls = $this->_config->getRouteTtls(); $routeName = Mage::app()->getRequest()->getRequestedRouteName(); if (isset($routeTtls[$routeName])) { $observer->getResponse()->setHeader('Cache-Control', $routeTtls[$routeName] ['cache_control'], false); } return $this; } }

37. <?xml version="1.0" encoding="UTF-8"?> <config> <ttls> <routes> <cms> <name>cms</name> <cache_control>public, max-age=3600</cache_control>

    </cms> <catalog> <name>catalog</name> <cache_control>public, must-revalidate, max-age=0</cache_cont <actions> <index> <cache_control>private, max-age=0</cache_control> </index> </actions> </catalog> </routes> </ttls>

38. VARNISH RESPECTS CACHE CONTROL Dispatch the headers that fit your

    application

39. Client Application Client Cache Reverse Proxy Cache GET / HTTP1.1

    Host: mystore.com GET / HTTP1.1 Host: mystore.com HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max-age=20

40. Client Application Client Cache Reverse Proxy Cache GET / HTTP1.1

    Host: mystore.com HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max-age=20

41. Client Application Client Cache Reverse Proxy Cache GET / HTTP1.1

    Host: mystore.com GET / HTTP1.1 Host: mystore.com HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max- age=20 HTTP1.1 200 OK Cache-Control: max-age=20 Client Client Cache GET / HTTP1.1 Host: mystore.com HTTP1.1 200 OK Cache-Control: max- age=20

42. Client Application Client Cache Reverse Proxy Cache Client Client Cache

    Gateway Cache Network Proxy Cache max-age s-maxage max-age s-maxage max-age s-maxage max-age max-age

43. VARNISH IS CONFIGURED USING VCL Send the correct headers you

    should not need to do much.

44. backend www1 { .host = "192.168.100.2"; .port = "8080"; }

    backend www2 { .host = "192.168.100.3"; .port = "8080"; } ........ director backend_director random { .retries = 5; { .backend = www1; .weight = 1; } { .backend = www2; .weight = 1; } { .backend = www3; .weight = 1; } { .backend = www4; .weight = 1; } { .backend = www5; .weight = 1; } { .backend = www6; .weight = 1; } { .backend = www7; .weight = 1; } }

45. sub vcl_deliver { # Set a cache header to allow

    us to inspect the response # headers during testing if (obj.hits > 0) { set resp.http.X-Cache = "HIT"; set resp.http.X-Cache-Hits = obj.hits; } else { set resp.http.X-Cache = "MISS"; } }

46. EDGE SIDE INCLUDES http://bit.ly/nITuFP

47. sub vcl_recv { set req.http.Surrogate-Capability = "magento=ESI/1.0"; return (lookup); }

    sub vcl_fetch { if (beresp.http.Surrogate-Control ~ "ESI/1.0") { # unset beresp.http.Surrogate-Control; esi; } return (deliver); }

48. max-age=3600 max-age=86400

49. max-age=3600 max-age=86400

50. ESI TAGS <esi:include src="/varnish/esi?attributes=%s"/>

51. /** * Render ESI tags for the block if needed

    * * @param Varien_Event_Observer $observer */ public function renderBlockEsiTag(Varien_Event_Observer $observer) { if (!$this->isEsiEnabled() || !$this->isVarnishEnabled()) { return $this; } $block = $observer->getEvent()->getBlock(); $transport = $observer->getEvent()->getTransport(); $tag = Mage::getModel('varnish/esi_tag_factory')- >create($block); if ($transport && $tag) { $transport->setHtml($tag->getHtml()); } return $this; }

52. /** * Render the html for the ESI tag *

    * @return string * @author Alistair Stead **/ public function getHtml() { return sprintf( '<esi:include src="/varnish/esi?attributes=%s"/>', $this->getAttributeHash() ); }

53. class Disclosure_Varnish_EsiController extends Mage_Core_Controller_Front_Action { public function indexAction() { $attributes

    = unserialize(base64_decode($this->getRequest()- >getParam('attributes'))); $context = Mage::getModel('varnish/esi_context'); $context->setData($attributes); $processor = Mage::getModel('varnish/esi_processor', $context); // Initialize the layout $this->loadLayout(); Mage::dispatchEvent('varnish_controller_esi_appendbody_before', array("response" => $this->getResponse())); $this->getResponse()->appendBody($processor->render()); Mage::dispatchEvent('varnish_controller_esi_appendbody_after', array("response" => $this->getResponse())); } }

54. FINAL PERFORMANCE RESULTS How much traffic did these modifications let

    us serve

55. TRAFFIC SAMPLE • Product Details page: 58k views per hour

    • Homepage: 50k requests per hour • Main Search : 70k requests per hour • Refined Search (via facets): 20k requests per hour • Add to Basket: 11k requests per hour • Login: 11k requests per hour • Category Pages: 46k requests per hour • Checkout: 6k requests per hour

56. Homepage Category Listings Product Detail Add to cart Login Search

    Purchase 0 375000 750000 1125000 1500000 Client Baseline Magento Baseline Magento Compiler Magento + Varnish FINAL PERFORMANCE RESULTS

57. NON CACHEABLE TRANSACTIONS Add to cart Purchase 0 7500 15000

    22500 30000 Client Baseline Magento Baseline Magento Compiler Magento + Varnish
58. None

59. THE TARGET ~ 300K REQUEST We achieved almost 14 x

    that with little effort.

60. IS VARNISH THE BEST SOLUTION? What do we need to

    consider?

61. VARNISH LIMITATIONS • Prior to V3 ESI not supported with

    GZIP • Cookies need to be managed carefully • Still need SSL endpoint • Beware cache stampede • ESI must have a TTL greater than the parent page • Only implements a subset of ESI • Shared cache consider using s-maxage with max-age

62. STALE WHILE Maintain a compromised UI while resolving content

63. ALTERNATE WHILE Provide alternate content will content is being resolved

64. ESI ANTI PATTERNS

65. MAGNIFY THE LOAD Multiple ESI requests in a page all

    directed at the same application Client Browser Varnish Port 80 Backend Apache Port 8080

66. CACHE BUSTING Static assets that out stay their welcome

67. REFERENCES http://bitly.com/pw3HXm

68. IMAGE CREDITS http://www.flickr.com/photos/bondgirly/4520060395/sizes/o/in/ photostream/

69. THANK YOU! • Email: [email protected] • Skype: astead-ibuildings • Twitter:

    @alistairstead

70. QUESTIONS? http://joind.in/3591

71. WE ARE HIRING! http://www.ibuildings.co.uk/about/careers/