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How Sysadmins view your stinkin' code

How Sysadmins view your stinkin' code

Talk given at Zendcon `12 discussing the dangers of devops in PHP and some tools to bring dev in harmony with ops.

Shawn Stratton

October 25, 2012
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  1. How Sysadmins View Your
    Stinkin’ Code
    Shawn Stratton
    Senior Systems Engineer / Architect
    Monday, October 29, 12

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  2. Who Am I?
    Currently work for Discovery Communications, Inc as a
    Systems Architect / Engineer.
    Became a Systems Architect 2011.
    Worked as a developer for NationalGuard.com,
    HowStuffWorks.com.
    PHP Developer since early 2000’s.
    Linux user since 1998.
    Monday, October 29, 12

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  3. Sysadmin at Work!
    http://xkcd.com/705/
    Sysadmins are
    neurotic, OCD, and
    more than a little
    Paranoid. Beware!
    Monday, October 29, 12

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  4. So what is a Sysadmin?
    Server monkey.
    Administrates servers to ensure uptime, stability, and
    performance.
    Responds to service outages, power outages, errors,
    etc. Often after hours.
    Monday, October 29, 12

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  5. Great Sysadmin Qualities
    Calm during the inevitable firestorm.
    Analytical and understanding of everything that is being
    ran.
    Obsession about Single Points of Failure, Bus Factor,
    anything that impacts downtime.
    Monday, October 29, 12

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  6. So who’s our nemesis?
    Monday, October 29, 12

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  7. Developers! Developers!
    Developers!
    Monday, October 29, 12

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  8. What is a Developer?
    Compiler, uses caffeine to compile business
    requirements into software.
    Constantly trying to “improve” software and add
    “functionality.”
    Monday, October 29, 12

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  9. What’s wrong with that?
    Nothing, but...
    Sysadmins care about stability, developers
    introduce instability.
    Monday, October 29, 12

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  10. And then there are devops...
    Monday, October 29, 12

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  11. So what do we care about?
    Fault tolerance.
    Error handling.
    Configurability.
    Scalability.
    Minimal resource
    utilization.
    Sanity.
    Monday, October 29, 12

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  12. Fault Tolerance
    System
    Multiple Servers.
    “Self Healing”
    systems.
    Software
    Exception handling.
    Tolerance just means try to handle errors as
    well as possible.
    Monday, October 29, 12

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  13. Error Reporting
    Meaningful errors that we can act on.
    Tell us what failed, not just that a failure has
    occurred.
    Clear messages that we can understand.
    You have a parse error at line x of file y.
    Concise errors that don’t overwhelm.
    Parseable so we can automate responses.
    Monday, October 29, 12

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  14. Configurability / Flexibility
    Make values configurable.
    Database endpoints.
    HTTP endpoints.
    Directories you write to/read from.
    Cache endpoints.
    Monday, October 29, 12

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  15. Scalability
    In our world, we talk about Horizontal Scalability (scale
    out vs. up.)
    Basically means the ability to handle more traffic by
    adding additional servers.
    Monday, October 29, 12

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  16. Disk Access
    Disk access is per server. Never assume you’ll talk to
    the same server twice in a row.
    NFS is slooow.
    Sticky sessions break more things than they fix.
    Monday, October 29, 12

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  17. Database
    Master / Slave
    Master should be
    write-only.
    Dedicated slave for
    reporting / backups.
    Clustered
    Don’t expect instant
    consistency.
    Be aware of what
    you’ll lose.
    Monday, October 29, 12

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  18. That’s all great but...
    Where are the tools?
    Monday, October 29, 12

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  19. Disclaimer
    I’m a Linux administrator, a Linux/Mac
    user, and the majority of PHP Serving is
    done via Linux. The tools discussed are
    Linux tools. I’ve written everything for
    what’s included in Ubuntu (the common
    denominator).
    Sorry Windows guys.
    Monday, October 29, 12

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  20. Making Requests
    Browser, like everyone else.
    curl from the command line.
    Monday, October 29, 12

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  21. Curl - Test output
    Monday, October 29, 12

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  22. Curl - Better than a Browser
    Monday, October 29, 12

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  23. Checking CPU /Memory
    utilization
    xDebug + Cache Grind.
    Zend Debugger + Zend
    Studio.
    XHProf.
    uptime
    top
    htop
    Profiling Monitoring
    Monday, October 29, 12

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  24. Load Averages - wtf?
    Commonly shown as 3 values, e.g. 1.06 1.14 1.36
    Numbers are load over 1 minute, 5 minutes, 15
    minutes
    Numbers represent load for a single core 1 = 100%
    Magic numbers (when you’re good):
    .7 per core is good utilization.
    1 per core is fully utilized (start planning new hw.)
    Monday, October 29, 12

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  25. xDebug
    http://xdebug.org/docs/install
    Simple, efficient, open source.
    Integrated into PHPStorm, Netbeans, and most every
    other IDE (beside Zend Studio).
    Monday, October 29, 12

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  26. xDebug + Cache Grind
    Monday, October 29, 12

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  27. Zend Debugger
    Very well integrated to Zend Studio & Zend Server.
    Dead simple to use.
    Monday, October 29, 12

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  28. Zend Debugger
    Monday, October 29, 12

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  29. XHProf
    https://github.com/facebook/xhprof
    Runs great constantly, but does not integrate well with
    an IDE.
    Monday, October 29, 12

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  30. Traditional (top)
    Monday, October 29, 12

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  31. Newer (htop)
    Monday, October 29, 12

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  32. Checking Disk IO
    inclued.
    dtrace.
    strace.
    Monday, October 29, 12

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  33. inclued
    Get a map of your includes. This is more useful
    than it seems.
    Monday, October 29, 12

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  34. dtrace
    From solaris, this will show you every system call,
    command is a bit complicated.
    Monday, October 29, 12

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  35. strace
    Different output and interaction than dtrace,
    same purpose.
    Monday, October 29, 12

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  36. Some other tools for
    Operations & Development.
    Monday, October 29, 12

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  37. CPU / System Metrics
    Too many to list but Cacti & Munin are common
    and have low barrier to entry.
    Monday, October 29, 12

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  38. Icinga / Nagios
    Alerts you to problems
    Monday, October 29, 12

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  39. Wrapping Up
    Monday, October 29, 12

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  40. Don’t
    Tell us it works on this machine or that machine.
    Forget to tell us your requirements while you’re making
    a deadline in the past.
    Claim you’ve found yet another [PHP|Apache|MySQL]
    bug when something doesn’t work.
    Do foolish things. e.g. Serve dynamically resized
    images (this is what gearman and caching is for.)
    Monday, October 29, 12

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  41. Do
    Control your IO & Network access.
    Be aware of your environment.
    Use the tools you have available and learn new ones.
    Monday, October 29, 12

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