MaxCDN Meetup Los Angeles, June, 2016

1. Content Caching with NGINX
and NGINX Plus
Kevin Jones - Sales Engineer, NGINX Software Inc.

2. ¯_( )_/¯
Wiki + Links

3. Agenda
• Brief Overview of Basic Caching Directives
• HA Caching Architectures
• Byte Range Request Caching
• Advanced Cache Control Using NGINX Plus

4. The Basics…The Basics…

6. proxy_cache_path
proxy_cache_path /path/to/cache levels=1:2
keys_zone=my_cache:10m max_size=10g inactive=60m;
Sets the path and other parameters of a cache.
Default: -
Context: http

7. proxy_cache
location / {
proxy_cache my_cache;
proxy_pass http://my_upstream;
}
Defines a shared memory zone used for caching.
Default: -
Context: http, server, location

8. proxy_cache_key
proxy_cache_key $proxy_host$request_uri$cookie_foo;
Defines the key for caching.
Default: proxy_cache_key $scheme$proxy_host$request_uri;
Context: http, server, location

9. proxy_cache_valid
proxy_cache_valid 200 301 302 1h;
proxy_cache_valid any 1m;
Sets caching time for different response codes.
Default: -
Context: http, server, location

10. proxy_cache_methods
proxy_cache_methods GET HEAD POST;
Configuration to specify HTTP methods that NGINX should cache.
Default: proxy_cache_methods GET HEAD;
Context: http, server, location

11. proxy_cache_min_uses
proxy_cache_min_uses 3;
Sets the number of requests before a response is cached.
Default: proxy_cache_min_uses 1;
Context: http, server, location

12. proxy_cache_lock
proxy_cache_lock on;
When enabled, only one request at a time will be allowed to populate a new
cache element.
Default: proxy_cache_lock off;
Context: http, server, location

13. proxy_cache_bypass
proxy_cache_bypass $arg_nocache $cookie_no_cache;
Defines the condition under which a response should not be taken from the
cache.
Default: -
Context: http, server, location

14. proxy_cache_use_stale
proxy_cache_use_stale error timeout http_500
http_502 http_503 http_504;
Determines in which cases a stale cached response can be used when an error
occurs to the proxied server.
Default: proxy_cache_use_stale off;
Context: http, server, location

15. “Woah.. I know NGINX…”
Learn MOAR here: https://www.nginx.com/blog/nginx-caching-guide/

16. High Availability
Caching

17. Why cluster?

18. Cost Impact

19. Why cant I just use shared volumes?

20. • Cache state is not synchronized
• NGINX can be sensitive to disk latency, rw’s
• Shared volume performance can be unreliable and
inconsistent

21. So what do we do?

22. Consistent Hash Architecture
• Hash based on proxy_cache_key
• Shard(ed) cache
• Effective use of storage
• Reduces Impact but can be costly to implement

23. Is there a cheaper way?

24. Active / Passive HA Cluster
• Both instances have fully-populated caches
• Minimal Cost and Impact

25. Active / Passive HA Cluster
On failure… “passive” node remains up with full cache

26. Active / Passive HA Cluster
“Active” node fetches from the origin when “passive” fails

27. Now something slightly more complicated but even more
effective…

28. Active / Active HA Cluster
Most effective use of hardware, doubling usage capacity.

29. Can I spread my cache across multiple disks?

30. proxy_cache_path /path/to/hdd1 levels=1:2
keys_zone=my_cache_hdd1:10m max_size=10g
inactive=60m use_temp_path=off;
proxy_cache_path /path/to/hdd2 levels=1:2
keys_zone=my_cache_hdd2:10m max_size=10g
inactive=60m use_temp_path=off;
split_clients $request_uri $my_cache {
50% “my_cache_hdd1”;
50% “my_cache_hdd2”;
}
server {
...
location / {
proxy_cache $my_cache;
proxy_pass http://my_upstream;
}
}
Dynamic proxy_cache Example

31. Byte Range Request
Caching

33. proxy_cache_path /tmp/mycache keys_zone=my_cache:10m;
server {
listen 80;
proxy_cache my_cache;
slice 1m;
proxy_cache_key $host$uri$is_args$args$slice_range;
proxy_set_header Range $slice_range;
proxy_http_version 1.1;
proxy_cache_valid 200 206 1h;
location / {
proxy_pass http://origin:80;
}
}
Slice Example

34. Proxy Cache Control

35. Enter…

36. Go to www.nginx.com/developer-license
Password: NGINX+MaxCDN (case sensitive)
Get started with an exclusive NGINX Plus Community
Developer License:

37. proxy_cache_path /tmp/cache keys_zone=my_cache:10m levels=1:2
inactive=60s;
map $request_method $purge_method {
PURGE 1;
default 0;
}
server {
listen 80;
server_name www.example.com;
location / {
proxy_pass http://localhost:8002;
proxy_cache my_cache;
proxy_cache_purge $purge_method;
}
}
Cache Purge API Configuration

38. Can I restrict access to the cache purge API?

39. http {
…
map $request_method $purge_method {
PURGE $purge_allowed;
default 0;
}
geo $purge_allowed {
127.0.0.0/24 1; # allow from localhost
192.168.1.1 1;
10.0.0.100 1;
172.0.200.10 1;
default 0; # deny from other
}
}
Restrict Access

40. Demo Time.

41. ¯_( )_/¯
Thanks for coming!