thijs feryn: varnish - where devops & sysadmins meet

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

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