Cut down presentation for DrupalCamp London 2013

1. Cache All The Things
Mike Bell - @mikebell_

2. About Me
Mike Bell
Lead Drupal Developer @ Ixis
@mikebell_
http://drupal.org/user/189605

3. Exactly what things?
well errr...
everything!

4. No really...
Frontend:
- HTML
- CSS
- Images
- Javascript
Backend:
- PHP
- MySQL
So pretty much everything then!

5. Where to start?
Ask yourself:
Why is my site slow?
a) Bad code
b) Bad server
c) It's not!

6. Bad Code?
Stop.
Caching will help... but it won't solve your
bigger issues.
There are tools to help - xhprof

7. Bad Server?
So how's £5.99 a month working out for you?
Caching will help... but again you still have
bigger issues.
Scale horizontally/vertically for a quick fix then
work on additional caching.

8. It's not!
I like you!
Caching is always a good thing, except when
you have to debug it...

9. Caching in Drupal
- Code Level (cache_get/cache_set)
- APC (not covered here)
- Resource caching (this get's tricky!)
- DB Layer
- CDNs (related to resource caching)

10. Code Level
Drupal has it's own caching api.
Module Developers use it!
cache_set - store data in Drupals cache table
cache_get - get data from Drupals cache table
You can even define your own cache tables!

11. Resource Caching
Many different types of resources
Each can be cached by different tools
Example:
- Drupals CSS/JS Cache
- Drupals Page Cache
- Boost
- Varnish

12. Resource Caching
Drupal default: CSS/JS and Page
(taken from mikebell.io - ooppss!)

13. Resource Caching - Boost
Boost - http://drupal.org/project/boost
Static caching for all Drupal Assets
Anonymous users only
Ideal for shared hosting environments
Potentially the easiest to setup

14. Resource Caching - Varnish
Application Accelerator
Linux Only
Caches resources based on initial view
Anonymous only - very picky with sessions and cookies
Insanely Powerful

15. Resource Caching - Varnish
Advanced setup - requires additional module
and VCL for Drupal
- http://drupal.org/project/varnish
Granular ttls (time to live)
Specific resource (image/css) and page
element! All available through VCL config.

16. Resource Caching - Varnish
Cache Stores
- RAM
- Disk
Ram - super fast - requires a lot of ram
Disk - fast - disk space is rarely an issue

17. Data Caching - memcached
Data and Database caching layer
Caches cache... (and things!)

18. Data Caching - memcached
Example:
Core cache - core cache tables (cache_*)
Moved into memcached and shared between multiple
instances across multiple servers
Simple api makes getting and setting easy
Drupal requires - http://drupal.org/project/memcache and
pecl extension

19. 3rd Party Caching - Akamai
One of the biggest caching providers
A high chance you've experienced Akamai
today without realising it.
Static cache of resources
Content Distribution Network
100+ Edge servers all over the world

20. 3rd Party Caching - Akamai
Coverage for DDOS attacks
- Active monitoring and defense
Advanced redirection rules through control panel
It's not cheap!
It's also pretty magical.

21. 3rd Party Caching - Cloudflare
Similar to Akamai
Smaller scale
Emphasis on security and DDOS protection

22. Content Distribution Network
CDNs for short
Offload resource handling to external provider
- Images
- Video
- Audio
- Large files
Syndicate content around the world

23. Content Distribution Network
Why use a CDN?
- Content is delivered quicker
-- Latency cut down
Pricing is granular - pay as you go type deal
Amazon + Rackspace Cloud Files

24. How does it all fit together?

25. What happens when it all goes wrong?

26. Caching to the rescue!
Each layer provides protection
3rd Party - shield 99% of anon traffic
Varnish - the rest
Anonymous users should never know your site
has issues.

27. Debugging Tips
Configure different urls for different platforms
- Easier to identify what cache layer has an issue
Don't be afraid to flush caches
- Your backend should be able to cope with it
Analyse headers! Drupal and Varnish provide a lot of info
Akamai information can be gleaned from additional http
headers.

28. Debugging Tips
Monitor each layer
- Icinga
- Pingdom

29. Any Questions?
Slide designs by Ritch Partridge (@ritchpartridge)