Varnish to the Rescue

Introduction to Varnish. Basics & pitfalls. Presented at techfusion.io

1. Varnish to the rescue Leszek Krupiński
2. @leafnode PHPers Manual Consultant Architect
3. intro
4. web 1. User 2. Browser 3. Server
5. user is impatient
6. fast!
7. 100ms
8. 1s = -11% Page Views -16% User Satisfaction -7% Conversion
9. 1-5s ! 32% consumers lost
10. (2012) average: 2.45s
11. Optimize application
12. • Frameworks • Limits • Time-consuming operations • Cost
13. Maybe it’s not needed?
14. Cache!
15. Many levels, many solutions
16. But… my site is very dynamic!
17. 1s TTL
18. From 20 rq/s to 1 rq/s in single apt-get install
19. Fresh content takes most hits
20. Varnish The Web Accelerator
24. Architecture
25. Works with the kernel not against it
26. mmap, threads, epoll, kqueue
27. Backends: memory, file
28. If it fits in memory, use memory
29. Works on HTTP headers
30. Cache-control, If-Modified-Since, Expires, Pragma, If-None-Match, Etag, Vary, Age
31. Varnish uses language both browser and backend know
32. In-memory logs
33. 75 000 rq/s at TMECC 143 000 rq/s at Redpill-Linpro
34. Do I need a lot of memory?
35. Nope
36. Fresh content takes most hits
37. Take that, slashdot effect!
38. Configuration
39. Lots of possibilities
40. Unfortunately, lots of possibilities
41. Varnish Configuration Language
42. Compiled directly to C
43. Hook-like configuration
44. vcl_fetch vcl_recv vcl_hit vcl_miss vcl_hash vcl_pass vcl_deliver vcl_error
46. restart
47. Objects req, bereq, resp, beresp, obj
48. Defaults
49. vcl_recv
53. vcl_hash
55. VMods
56. throttle, cookie, shield, redis, memcached, curl, url code, redirect…
57. Varnish: load balancer failover system
59. Directors
60. Default: random
61. Round-robin, client, hash, dns
62. Health check
64. Saint mode
65. Grace mode
66. Two hard things
67. Invalidate cache
68. Ban list Efficient way to invalidate cache
69. Over HTTP
70. Use PURGE header
74. Real life issues
75. Cookies
76. Varnish does not cache when cookies are involved
77. Ignore cookies
79. Pick cookies
81. Pick URLs
83. Redirects
84. POST
85. PHP sessions
86. CURL VMod
89. PHP + memcached
91. mobile detection
93. mobile detection II
95. VMod: DeviceAtlas Mobile Detection
96. Cache “one-time” data
97. Example: dynamic image resizing
98. 1B pictures 10 sizes
99. apache + moddims
100. Fresh content takes most hits
101. Different TTL for different parts?
102. ESI!
105. Testing?
106. jQuery plugin
107. Just in! Varnish 4.0
108. Log query language, background fetch, byte counters, security improvements
109. http://speakerdeck.com/leafnode