Here's the full talk: https://wordpress.tv/2017/12/10/nathaniel-schweinberg-scalable-highly-available-wordpress-on-aws/ WordPress at its heart is a blogging platform, designed to serve a site that’s largely read-only. Logging in isn’t necessary unless you’re an admin looking to write a blog post or adjust settings. This is a good thing! Scaling a site that’s predominantly read-only is very easy because you can place a CDN like CloudFront or a page cache like Varnish in front of a single server and serve many, many requests from hardware as cheap as $5 per month. But what happens when you have a site that isn’t read-only? What happens when you have, for example, a WooCommerce site with a couple hundred transactions a day? Or perhaps you run a news site with millions of pageviews a month? All of a sudden, that poor $5 server is catching on fire and asking what it did to deserve this! Running a single server like this is called a “Single Point of Failure” and that is a very big no-no to run in a production environment. Cloud servers are ephemeral in nature and aren’t guaranteed to stay up 100% of the time. Any number of things can go wrong, which is why designing your infrastructure to respond to bursts of traffic as well as be able to continue serving requests when servers go down is paramount to a reliable production environment. This talk will give an overview of what is involved from moving from a single-server setup to a scalable, highly-available infrastructure on AWS.

1. Scalable,
Highly-Available
WordPress on AWS
Nathaniel Schweinberg

2. Scalability refers to
the ability of an infrastructure
to change its size on-demand.

3. Vertical Scaling
Increase a server’s
CPU, Memory,
or Disk Space

4. Horizontal Scaling
Add more servers to
your infrastructure

5. High Availability refers to an
infrastructure’s ability to
continue serving requests
when resources are no longer
available.

6. https://humans-eat-cake.com
(Most basic hosting environments)

7. https://humans-eat-cake.com

8. https://humans-eat-cake.com

9. A Single Point of Failure refers
to a resource or access point
that, if it fails, prevents the
application from serving
requests.

10. https://humans-eat-cake.com

11. https://humans-eat-cake.com

12. https://humans-eat-cake.com

13. Overwhelming load
& Servers failing
Two Problems
a growing site faces

14. Let’s solve these problems!

15. Assumption: not using Docker

16. Challenge:
Using a single server is a SPoF.
How do we route traffic to more
than one server using one domain?

17. Solution:
Elastic Load Balancers.

18. https://humans-eat-cake.com

19. Challenge:
We need to deploy our application.
How do we deploy our code to
multiple servers at the same time?

20. Solution:
CodeDeploy.

27. Challenge:
The database lives on a single
instance which is a SPof.
How do we ensure the database is
highly-available?

28. Solution:
RDS with
Multi-AZ enabled.

29. us-east-1a us-east-1b us-east-1c

30. us-east-1a us-east-1b us-east-1c

31. us-east-1a us-east-1b us-east-1c

32. us-east-1a us-east-1b us-east-1c

33. us-east-1a us-east-1b us-east-1c

34. Challenge:
Our site hits /r/all and we’re
flooded with traffic.
How do we respond to traffic
without manual intervention?

35. Solution:
EC2 AutoScaling Groups.

43. Challenge:
We are running multiple servers
behind a load balancer and need to
make changes to a server’s config.
How do we ensure changes made to
one server propagate to the others?

44. Solution:
AMI’s.
(Amazon Machine Images)

45. Challenge:
As traffic increases, the database
gets overwhelmed with queries.
How do we minimize queries to the
database, while still serving fresh
content?

46. Solution:
ElastiCache.

48. More questions to ask:
How do I automate building AMI’s?
How do you spin up infrastructure?
How do you reduce server load?

49. Thanks