Caching the Uncacheable: Leveraging Your CDN to Cache Dynamic Content

June 25, 2014. Hooman Beheshti, VP Technology at Fastly, discusses how using a real-time, modern CDN that provides instant cache invalidation and real-time analytics allows for instantaneous control over dynamic content caching. In this session, he looks at the challenges CDNs face with dynamic content and how you can use programmatic means to fully integrate your applications with your CDN.

Transcript

1. Caching  The   Uncacheable:     Leveraging  Your  CDN  to  Cache  Dynamic   Content   Hooman  Behesh+,  VP  Technology  
2. Dynamic  Content  Is  Really   Interes=ng!  
3. What  Is  Dynamic  Content?   •  Stuff  that’s  not  sta+c!   •  With  web  traffic,  generally  the  base  HTML   –  Big  deal  because  it’s  blocking   –  And  some+mes  the  largest  object  à  longer  download   •  Could  be  other  things  too   –  AJAX  calls   –  API  calls   •  More…  
5. Blocking  
8. Classically,  with  dynamic  content…   Caching  
9. Dynamic  Content  Caching  Problems   •  Serving  stale  pages   – Lack  of  good  invalida+on  framework    
10. Caching     vs.     Invalida=on  
14. We  tried…  
15. Dynamic  Content  Caching  Problems   •  Serving  stale  pages   – Lack  of  good  invalida+on  framework    
16. Dynamic  Content  Caching  Problems   •  Serving  stale  pages   – Lack  of  good  invalida+on  framework   •  Real-­‐+me  visibility   – Real-­‐+me  analy+cs/stats   – Real-­‐+me  logging    
17. CDNs  and  Dynamic  Content   •  Generally,  handling  dynamic  content  has  been   a  maRer  of  transport   – Op+mize  from-­‐origin  delivery   – “DSA”  (Dynamic  Site  Accelera+on)   – Middle  mile  op+miza+ons   – TCP  tweaks  
18. Dynamic  Content,  Tradi=onally   CDN  Node   Client   Origin   Some  TCP  Tweaks  
19. Dynamic  Content,  Tradi=onally   CDN  Node   CDN  Node   Client   Origin   Lots  of  TCP  Tweaks  
20. Dynamic  Content,  Tradi=onally   •  We  some+mes  do  micro  caching  of  HTML   –  Short  TTL  for  HTML  content   –  Not  full  proof   •  Ex:  news  stories  faux-­‐pas!   •  ESI  (Edge  Side  Includes)   –  Par+al  caching   –  Hard  and  onerous    
21. Actually…   •  Dynamic  content  is  more  cacheable  than  we   think   •  Sta+c  for  short  periods  of  +me   •  Unpredictable  invalida+on   –  Standard  HTTP  caching  rules  aren’t  good  enough  
22. A  Lot  BeMer!   CDN  Node   CDN  Node   Client   Origin  
24. Blocking  
27. So  Many  Benefits!   •  Performance   –  Faster  +me  to  first  byte   –  Faster  start  render   –  Happy  users!   •  Offload   –  Less  work  for  our  servers   –  Less  bandwidth  at  origin  
28. What  would  make  it  beMer?  
29. Programma=c  Invalida=on   •  Invalida+on  API   •  Granular   •  Instantaneous   – Big  problem  with  classic  CDNs  (mul+-­‐minute   purges)  
30. Power  of  the  Purge!   •  Instant  purging:   – As  a  page  gets  published,  a  purge  command  also   gets  published   – Instant  means:  predictable  and  determinis+c   behavior    
31. Power  of  the  Purge!   •  Purge  dependencies   – Surrogate  Keys   – Using  tags  to  purge  en+re  chunks  of  content  at   once    
32. More  than  just  Invalida=on…  
33. The  Influence  of  Clouds   •  The  CDN  is  an  extension  of  the  app   •  No  longer  a  black  box   •  Real-­‐+me  integra+on  with  the  app   •  Infrastructure  as  code   – Your  content  =>  You  need  control  
34. Control   •  Programmability   – Configura+on  API   – Invalida+on  API   – Instantaneous  and  real  +me   – Granular  caching   •  Ex:  Geo-­‐based  caching  
35. Control  at  the  Edge   •  Moving  app  logic  to  the  edge   •  VCL   – Varnish  Configura+on  Language   – Script-­‐like  configura+on  for  func+onality  at  the   edge  
36. Visibility   •  Real  +me  analy+cs   –  Network  stats   –  HTTP  stats  (status  codes  ,  etc)   –  Caching  stats  (hits,  misses,  etc)   –  Stats  API   •  Logging   –  Real  +me  logs   –  Streaming  to  various  log  des+na+ons  
37. Example:   CMS  +  Purge  
38. WordPress:  Before   CDN  Node  
39. WordPress:  Before   CDN  Node  
40. WordPress:  Before   CDN  Node  
41. WordPress:  Before   CDN  Node  
42. WordPress:  Before   CDN  Node   Cache  
44. WordPress:  AWer   CDN  Node  
45. WordPress:  AWer   CDN  Node   HTTP/1.1 200 OK Content-Type: text/html Content-Length: 55,666 Cache-Control: Long Time, totally!
46. WordPress:  AWer   CDN  Node  
47. WordPress:  AWer   CDN  Node  
48. WordPress:  AWer   CDN  Node   PURGE  
49. WordPress:  AWer   CDN  Node   PURGE  
50. WordPress:  AWer   CDN  Node   PURGE   (Has  to  be  instantaneous!)  
51. WordPress:  AWer   CDN  Node   HTTP/1.1 200 OK Content-Type: text/html Content-Length: 55,666 Cache-Control: Long Time, totally!
52. Example:   Beacon  Termina=on  at  the  Edge  
53. Before   CDN  Node   Origin   Log  Analysis   http://collector.site.com/beacon.img?a=1&b=2&c=3
54. Before   CDN  Node   Origin   Log  Analysis   http://collector.site.com/beacon.img?a=1&b=2&c=3
55. Before   CDN  Node   Origin   Log  Analysis   HTTP/1.1 200 OK Pragma: no-cache Expires: Wed, 19 Apr 2000 11:43:00 GMT Cache-Control: no-cache, no-store Last-Modified: Wed, 21 Jan 2004 19:51:30 GMT Content-Type: image/gif Date: Fri, 20 Jun 2014 12:22:20 GMT Server: Apache Content-Length: 35 http://collector.site.com/beacon.img?a=1&b=2&c=3
56. Before   CDN  Node   Origin   Log  Analysis   HTTP/1.1 200 OK Pragma: no-cache Expires: Wed, 19 Apr 2000 11:43:00 GMT Cache-Control: no-cache, no-store Last-Modified: Wed, 21 Jan 2004 19:51:30 GMT Content-Type: image/gif Date: Fri, 20 Jun 2014 12:22:20 GMT Server: Apache Content-Length: 35 http://collector.site.com/beacon.img?a=1&b=2&c=3
57. AWer   CDN  Node   Origin   http://collector.site.com/beacon.img?a=1&b=2&c=3
58. AWer   CDN  Node   Origin   HTTP/1.1 200 OK Pragma: no-cache Expires: Wed, 19 Apr 2000 11:43:00 GMT Cache-Control: no-cache, no-store Last-Modified: Wed, 21 Jan 2004 19:51:30 GMT Content-Type: image/gif Date: Fri, 20 Jun 2014 12:22:20 GMT Server: Apache Content-Length: 35 http://collector.site.com/beacon.img?a=1&b=2&c=3
59. AWer   CDN  Node   Origin   HTTP/1.1 204 No Content Date: Sat, 21 Jun 2014 23:21:12 GMT Server: Awesome Server Content-Length: 0 http://collector.site.com/beacon.img?a=1&b=2&c=3
60. AWer   CDN  Node   Origin   Syslog  /  S3  /  FTP/etc   http://collector.site.com/beacon.img?a=1&b=2&c=3
61. Example:   Edge-­‐generated  Content  
62. JSON  Data  Center  ID   CDN  Node   Origin   http://www.site.com/which_datacenter.js
63. JSON  Data  Center  ID   CDN  Node   Origin   { ‘datacenter’ : ‘SJC’ } http://www.site.com/which_datacenter.js
64. VCL  Snippet  
65. More  Examples   •  Caching  with  tracking  cookies:   –  hRp://www.fastly.com/blog/how-­‐to-­‐cache-­‐with-­‐ tracking-­‐cookies   •  API  Caching:   –  hRp://www.fastly.com/blog/api-­‐caching-­‐part-­‐iii  (part   3,  with  links  to  previous  two  parts)   •  Log  Streaming:   –  hRp://www.fastly.com/blog/+ps-­‐for-­‐streaming-­‐logs    
66. Let’s  Sum  Up!  
67. Summary   •  Dynamic  content  can  be  cached   –  We  need  instant  purging   –  We  need  real-­‐+me  logs  and  stats   •  Real-­‐+me  integra+on  of  our  CDN  with  our  app  is  cool!   –  Extensive/granular  API  to  control  the  CDN   –  Control  and  visibility  at  the  edge  lets  us  be  really  crea+ve   •  Never  use  “Long Time, totally!” in  a  Cache-Control header!    
68. Thank  you!   hooman@fastly.com