Varnish your application - Make it fly!

Apply varnish to a pre-existing application to improve performance and scalability. Delivered at #phpnw11

Transcript

1. VARNISH
   YOUR
   APPLICATION
   Make it fly!
   

   View Slide

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
   

   View Slide

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

   View Slide

4. PERFORMANCE
   Vs
   CONVERSION RATE
   These are directly linked!
   

   View Slide

5. PERCEIVED PERFORMANCE
   Vs
   PHYSICAL PERFORMANCE
   Is there an easy route to performance?
   

   View Slide

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

   View Slide

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

   View Slide

8. +4,000,000
   Requests per hour
   

   View Slide

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

   View Slide

10. CACHING PROXY?
    It is...
    

    View Slide

11. LOAD BALANCER?
    It can do that too!
    

    View Slide

12. HTTP ACCELERATOR
    It may just be magic!
    

    View Slide

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
    

    View Slide

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

    View Slide

15. "WITH GREAT POWER COMES
    GREAT RESPONSIBILITY"
    

    View Slide

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

    View Slide

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

    View Slide

18. HTTP 1.1
    $ curl -I magentocommerce.com
    

    View Slide

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
    

    View Slide

20. HTTP 1.1 HEADERS
    Request modifiers / Response parameters
    

    View Slide

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

    View Slide

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

    View Slide

23. EXPIRATION HEADERS
    • Cache-Control
    • Expires
    

    View Slide

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

    View Slide

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

    View Slide

26. HTTP CACHE HEADERS
    Should only work with safe HTTP verbs GET & HEAD
    

    View Slide

27. HTTP 1.1 REQUEST FLOW
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

33. EXPIRATION ALLOWS YOU TO
    SCALE
    VALIDATION SAVES
    BANDWIDTH
    Fewer requests hitting your server and client speed is better too!
    

    View Slide

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

    View Slide

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

    View Slide

36. 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;
    }
    }
    

    View Slide

37. 
    
    
    
    
    cms
    public, max-age=3600
    
    
    catalog
    public, must-revalidate, max-age=0
    
    private, max-age=0
    
    
    
    
    
    

    View Slide

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

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

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
    

    View Slide

43. VARNISH IS CONFIGURED
    USING VCL
    Send the correct headers you should not need to do much.
    

    View Slide

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; }
    }
    

    View Slide

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";
    }
    }
    

    View Slide

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

    View Slide

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);
    }
    

    View Slide

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

    View Slide

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

    View Slide

50. ESI TAGS
    
    

    View Slide

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;
    }
    

    View Slide

52. /**
    * Render the html for the ESI tag
    *
    * @return string
    * @author Alistair Stead
    **/
    public function getHtml()
    {
    return sprintf(
    '',
    $this->getAttributeHash()
    );
    }
    

    View Slide

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()));
    }
    }
    

    View Slide

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

    View Slide

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
    

    View Slide

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
    

    View Slide

57. NON CACHEABLE
    TRANSACTIONS
    Add to cart
    Purchase
    0 7500 15000 22500 30000
    Client Baseline Magento Baseline Magento Compiler
    Magento + Varnish
    

    View Slide

58. View Slide

59. THE TARGET ~ 300K REQUEST
    We achieved almost 14 x that with little effort.
    

    View Slide

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

    View Slide

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
    

    View Slide

62. STALE WHILE
    Maintain a compromised UI while resolving content
    

    View Slide

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

    View Slide

64. ESI ANTI PATTERNS
    

    View Slide

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
    

    View Slide

66. CACHE BUSTING
    Static assets that out stay their welcome
    

    View Slide

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

    View Slide

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

    View Slide

69. THANK YOU!
    • Email: astead@ibuildings.com
    • Skype: astead-ibuildings
    • Twitter: @alistairstead
    

    View Slide

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

    View Slide

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

    View Slide