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