Thijs Feryn: Varnish - where devops & sysadmins meet
Post on 08-Apr-2017
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Where developers
& sysadmins meet
By Thijs Feryn
Varnish
Hi, I’m Thijs
I’m @ThijsFeryn on Twitter
I’m an Evangelist
At
I’m an at
Evangelist
I’m a at
board member
Early days
Down
Website performance?
More servers
Identify slowest part
Optimize database
Optimize runtime
After a while you hit the limits
Caching
Memcached or
Redis
Optimize database
Optimize runtime
Avoid
Avoid
Varnish
Hit rate?
Cookies?
Cache Control?
Developers
Sysadmins
✓State ✓Performance ✓Scalability ✓Cache invalidation ✓Architecture
People often forget
Who writes the VCL?
Varnish still considered a
sysadmin responsibility
Coaching developers & sysadmins
✓No state unless required ✓Cache-control discipline ✓Chop pages into content
blocks ✓AJAX or ESI ✓Reasonable cache
variations ✓Cache invalidation strategy
Advice for developers
✓Normalize input ✓Cookies blacklist/whitelist ✓URL blacklist/whitelist
VCL
When you respect HTTP
Developers are bridging the gap too
Collaboration & empathy
AKA DevOps
Architecture
Service Oriented
Architecture
RESTCacheable in Varnish if done right
Monolith vs
Microservices
Distributed systems
Big Data & NoSQL
Async, concurrent & non-blocking processing
Common goal
Better end-user experience
Frameworks & CMS’es
Bullet proof?
Well-designed software should
be more scalable
Well-designed software should
be faster
Well-designed software doesn’t
need much caching?
Always cache … when you can
Well-designed software doesn’t require much VCL
Well-designed software knows
how to purge the cache
Challenges
Caching state of mind
Purging
There are only two hard things in Computer Science: cache invalidation and naming things.
—- Phil Karlton
SSL termination+ SSL
awareness in application
Static assetsTo
cache or not to cache?Invalidate
or not?
Clustering & HA
Varnish flo
w
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