Varnish: How We Do It

SF Varnish Meetup
June 1st, 2015

Transcript

1. Varnish:
   How we do it
   SF Varnish Meetup
   June 1st 2015
   Matt Robenolt
   

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2. Hello
   < me irl
   

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3. Lead Operations Engineer
   

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4. First Generation
   edge
   (haproxy)
   shield
   app
   (python)
   Failover
   

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5. Why this sucked
   

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6. Duplicate routing logic
   Complex Caching logic
   WasteD RAM for failover
   Why this sucked
   

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7. Failover == lose all cache
   Varnish held cache rules
   Hard to add/remove backends
   Why this sucked
   

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8. Current Generation
   edge
   shield
   app
   (python)
   

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9. Why this is rad
   

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10. App owns all caching logic
    Unified request routing
    Utilize RAM from all nodes
    Why this is rad
    

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11. If-Modified-Since
    Vary on cookie values
    Less deploys to Varnish
    Why this is rad
    

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12. 60,000
    15,000
    13,000
    Caching funnel
    edge
    shield
    app
    

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13. edge
    shield
    app
    Onion skin view
    

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14. edge
    shield
    app
    recv
    pass
    fetch
    hit
    miss
    hash
    synth
    fetch
    deliver
    error
    Onion skin view
    

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15. edge 60,000 req/s
    

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16. edge
    Closest to users (geographically)
    Absorbs most traffic
    Blocks abuse
    60,000 req/s
    

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17. edge
    Makes decisions for shield
    Sort querystrings (boltsort/std)
    Promote cookies to headers
    60,000 req/s
    

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18. Cookies.
    as headers?
    Why?
    

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19. Vary: Cookie-sessionid
    

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20. shield 15,000 req/s
    

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21. shield
    Routing to app backends
    Serve stale content (grace)
    Do If-modified-Since
    15,000 req/s
    

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22. shield
    Parse response cache rules
    Backend healthchecks
    Store lots of content
    15,000 req/s
    

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23. application 13,000 req/s
    

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24. application
    Declare response cache rules
    Respond to If-modified-Since
    13,000 req/s
    

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25. WaiT.
    13,000 req/s still?
    

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26. 46%
    53%
    1%
    App Response Codes
    

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27. 46%
    53%
    1%
    App Response Codes
    304
    200
    

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28. miss Hit Hit/update
    If-Modified-Since
    Hit/IMS
    200 OK 200 OK 304 Not Modified
    v1 v2
    

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29. tl;dr
    60k req -> 7k at app
    Every request thru Varinsh
    Complex logic written once
    

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30. tl;dr
    App has complete control
    We still <3 haproxy
    Each layer worth deep dive
    

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31. We’re hiring people
    who hate comptuers.
    disqus.com/jobs
    

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32. Check it.
    HTTP for Great Good
    speakerdeck.com/mattrobenolt/http-for-great-good
    Cheating Your Way to
    #webscale
    speakerdeck.com/mattrobenolt/cheating-your-way-to-webscale
    

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33. Questions? I have answers.
    ^
    github.com/mattrobenolt
    @mattrobenolt
    some
    

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