Varnish: where developers & sysadmins meet - Varnish Summit Amsterdam 2015
Where developers& sysadmins meetBy Thijs FerynVarnish
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Hi, I’m Thijs
I’m@ThijsFerynon Twitter
I’m anEvangelistAt
I’m anatEvangelist
I’m aatboard member
Earlydays
Down
Website performance?
More servers
Identify slowest part
Optimize database
Optimize runtime
After a while youhit the limits
Caching
MemcachedorRedis
Optimize databaseOptimize runtimeAvoidAvoid
Varnish
Hit rate?
Cookies?
Cache Control?
DevelopersSysadmins
✓State✓Performance✓Scalability✓Cache invalidation✓ArchitecturePeople often forget
Who writesthe VCL?
Varnish stillconsidered asysadminresponsibility
Coaching developers& sysadmins
✓No state unless required✓Cache-control discipline✓Chop pages into contentblocks✓AJAX or ESI✓Reasonable cachevariations✓Cache invalidation strategyAdvice for developers
✓Normalize input✓Cookies blacklist/whitelist✓URL blacklist/whitelistVCL
When you respect HTTP
Developersare bridgingthe gap too
Collaboration & empathyAKA DevOps
Architecture
ServiceOrientedArchitecture
RESTCacheable in Varnish if done right
MonolithvsMicroservices
Distributedsystems
Big Data &NoSQL
Async,concurrent &non-blockingprocessing
Common goal
Better end-user experience
Frameworks & CMS’es
Bulletproof?
Well-designedsoftware shouldbe more scalable
Well-designedsoftware shouldbe faster
Well-designedsoftware doesn’tneed muchcaching?
Always cache… when you can
Well-designedsoftware doesn’trequire much VCL
Well-designedsoftware knowshow to purge thecache
Challenges
Caching state of mind
Purging
There are only two hardthings in ComputerScience: cacheinvalidation and namingthings.—- Phil Karlton
SSL termination+ SSL awareness in application
Static assetsTo cache or not to cache?Invalidate or not?
Clustering & HA
Varnish flow