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Building a Resilient API with open source

Building a Resilient API with open source

Tools and techniques GitHub employs to handle API changes.

Wynn Netherland

July 23, 2014
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Transcript

  1. !
    Building a Resilient API
    with open source
    Wynn Netherland
    GitHub

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  2. !
    Hello, my name is Wynn.

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  4. Folks call me @pengwynn.

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  5. !
    I work @ GitHub.

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  6. !
    GitHub makes software
    for people who make software.

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  7. !
    I work mostly on the GitHub API.

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  8. !
    I make software for computers
    who work for people
    who make software
    and other stuff.
    — me, at Thanksgiving


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  9. !
    Building a Resilient API
    with open source
    I want to talk about

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  10. !
    re·sil·ient
    /ri'zilyənt/
    able to recoil or spring back into shape after
    stretching, bending, or compressing
    "

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  11. !
    Stretching

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  12. !
    # LOAD #

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  13. !
    Bending

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  14. !
    Feature changes

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  15. !
    % Bug fixes

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  16. !
    Compressing

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  17. !
    Feature removal

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  18. !
    Internal refactoring

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  19. !
    Infrastructure changes

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  20. !
    Change happens.

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  21. !
    Who 301'd my cheese?

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  22. !
    measure change &
    minimize change '
    handle change (
    At GitHub, we
    so we can
    in order to

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  23. !
    Measuring change &

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  24. !
    Use data to inform decisions.

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  25. !
    How often is this feature used?

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  26. !
    Who is using this feature?

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  27. !
    ”If an API method is removed
    in the woods, and nobody is there to call it,
    does it still respond with 410?”
    !
    — unknown

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  28. !
    /graph me -1hour @api.status.codes
    !

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  29. !
    )
    Chatops

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  30. !
    Hubot *

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  31. !
    hubot.github.com

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  32. !
    /graph me -1hr @api.queries.serialized
    !

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  33. !
    /graph me -3hr @api.events.delivered
    !

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  34. !
    The Graph Store +

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  35. !
    The Graph Store +
    There's a graph for that™

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  36. !
    The Graph Store +
    There's a graph for that™
    …if not, make one.

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  37. !
    Built on Graphite

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  38. !

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  39. !

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  40. !
    ,
    Instrumentation

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  41. !
    # counter
    GitHub.stats.increment("the-thing.the-action")
    !
    # gauge
    GitHub.stats.gauge("the-thing.the-gauge", thing.current_reading)
    !
    # timing
    GitHub.stats.time("the-thing.the-operation") { the_operation }
    -

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  42. !
    # counter
    GitHub.stats.increment("the-thing.the-action")
    !
    # gauge
    GitHub.stats.gauge("the-thing.the-gauge", thing.current_reading)
    !
    # timing
    GitHub.stats.time("the-thing.the-operation") { the_operation }
    -

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  43. !
    # counter
    GitHub.stats.increment("the-thing.the-action")
    !
    # gauge
    GitHub.stats.gauge("the-thing.the-gauge", thing.current_reading)
    !
    # timing
    GitHub.stats.time("the-thing.the-operation") { the_operation }
    -

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  44. !
    github.com/graphite-project

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  45. !
    .
    Logging

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  46. !
    /splunk -3m @production "timeline.json"
    !
    pengwynn:
    !
    2014-07-10T10:12:19-07:00 github-fe126-cp1-prd local7:info unicorn_rails[11990]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"
    request_id="AD003EA0:5BD8:4B8AE05:53BEC973" remote_address=192.168.1.1
    request_method=get path_info="/timeline.json" content_length=375
    user_agent="@gitlost account on twitter, Python urllib2" accept=nil language=nil
    status=410 at=finish elapsed=0.005
    2014-07-10T10:12:19-07:00 github-fe126-cp1-prd local7:info unicorn_rails[11990]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"
    user=nil repo=nil route=nil zone=UTC referrer=nil requested_at="2014-07-10
    17:12:19 UTC" url="https://github.com/timeline.json" controller=EventsController
    action=index request_id="AD003EA0:5BD8:4B8AE05:53BEC973" dbconn=write
    serializer=json at=start
    2014-07-10T10:12:19-07:00 github-fe117-cp1-prd local7:info unicorn_rails[12813]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"

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  47. !
    /splunk -3m @production "timeline.json"
    !
    pengwynn:
    !
    2014-07-10T10:12:19-07:00 github-fe126-cp1-prd local7:info unicorn_rails[11990]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"
    request_id="AD003EA0:5BD8:4B8AE05:53BEC973" remote_address=192.168.1.1
    request_method=get path_info="/timeline.json" content_length=375
    user_agent="@gitlost account on twitter, Python urllib2" accept=nil language=nil
    status=410 at=finish elapsed=0.005
    2014-07-10T10:12:19-07:00 github-fe126-cp1-prd local7:info unicorn_rails[11990]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"
    user=nil repo=nil route=nil zone=UTC referrer=nil requested_at="2014-07-10
    17:12:19 UTC" url="https://github.com/timeline.json" controller=EventsController
    action=index request_id="AD003EA0:5BD8:4B8AE05:53BEC973" dbconn=write
    serializer=json at=start
    2014-07-10T10:12:19-07:00 github-fe117-cp1-prd local7:info unicorn_rails[12813]:
    app=github env=production enterprise=false now="2014-07-10T10:12:19-07:00"

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  48. !
    /splunk -3m @production "timeline.json" | stats count
    by status, avg(elapsed)
    !
    pengwynn:
    ┌──────┬────────────┐
    │status│avg(elapsed)│
    ├──────┼────────────┤
    │200 │0.067745 │
    ├──────┼────────────┤
    │410 │0.005597 │
    └──────┴────────────┘

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  49. !
    key=value logging

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  50. !
    /
    app=github
    env=development
    enterprise=false
    now="2014-07-21T11:49:45-07:00"
    request_id=f80765a8-8aa9-4e92-b32b-01300193631a
    remote_address=127.0.0.1
    request_method=get
    path_info="/"
    content_length=1866
    user_agent=curl/7.30.0
    accept=*/*
    language=nil
    status=200
    at=finish
    elapsed=0.110

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  51. !
    /
    app=github
    env=development
    enterprise=false
    now="2014-07-21T11:49:45-07:00"
    request_id=f80765a8-8aa9-4e92-b32b-01300193631a
    remote_address=127.0.0.1
    request_method=get
    path_info="/"
    content_length=1866
    user_agent=curl/7.30.0
    accept=*/*
    language=nil
    status=200
    at=finish
    elapsed=0.110

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  52. !
    curl https://api.github.com/ -I | grep Request-Id

    /
    !
    X-GitHub-Request-Id:
    4317CCE2:6434:21DCB73:53CD6239

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  53. !
    curl https://api.github.com/ -I | grep Request-Id

    /
    !
    X-GitHub-Request-Id:
    4317CCE2:6434:21DCB73:53CD6239
    A single identifier to trace requests through logging.

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  54. !
    /splunk -3m @production request_id=f80765a8-8aa9-4e92-
    b32b-01300193631a
    !

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  55. !
    github.com/asenchi/scrolls

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  56. !
    github.com/technoweenie/grohl
    If Golang is your thang.

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  57. !
    Logstash, Splunk*, Loggly*
    *SaaS solutions, not open source

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  58. !
    Minimizing change '

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  59. !
    Isolation

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  60. !
    tree -d -L 2 github

    /
    github
    ├── app
    │ ├── api
    │ ├── assets
    │ ├── controllers
    │ ├── helpers
    │ ├── mailers
    │ ├── models
    │ ├── view_models
    │ └── views
    ├── bin
    ├── config
    │ ├── inititalizers
    ...

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  61. !
    tree -d -L 2 github

    /
    github
    ├── app
    │ ├── api
    │ ├── assets
    │ ├── controllers
    │ ├── helpers
    │ ├── mailers
    │ ├── models
    │ ├── view_models
    │ └── views
    ├── bin
    ├── config
    │ ├── inititalizers
    ...
    Sinatra app
    inside a
    Rails app

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  62. !
    tree -d -L 2 github

    /
    github
    ├── app
    │ ├── api
    │ ├── assets
    │ ├── controllers
    │ ├── helpers
    │ ├── mailers
    │ ├── models
    │ ├── view_models
    │ └── views
    ├── bin
    ├── config
    │ ├── inititalizers
    ...
    Sinatra app
    inside a
    Rails app

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  63. !
    Shared
    business logic
    data access
    logging
    instrumentation
    plumbing
    Independent
    workflows
    output

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  64. !
    Testing
    ❯ testrb test/integration/api/repos_test.rb
    Loading suite in dotcom mode ...
    Run options:
    # Running tests:
    Finished tests in 30.638101s, 4.7979 tests/s, 64.7886 assertions/s.
    147 tests, 1985 assertions, 0 failures, 0 errors, 0 skips
    ruby -v: ruby 2.1.0p0-github (development) [x86_64-darwin13.0]

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  65. !
    Rack::Test

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  66. !
    brynary/rack-test
    github.com/

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  67. !
    # test/integration/api/root_test.rb
    !
    test "provides hypermedia URLs to top-level resources" do
    get "/"
    data = JSON.parse(last_response.body)
    assert_equal 200, last_response.status
    assert_equal "https://#{GitHub.api_host_name}/user",
    data["current_user_url"]
    end
    -

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  68. !
    # test/integration/api/root_test.rb
    !
    test "provides hypermedia URLs to top-level resources" do
    get "/"
    data = JSON.parse(last_response.body)
    assert_equal 200, last_response.status
    assert_equal "https://#{GitHub.api_host_name}/user",
    data["current_user_url"]
    end
    -

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  69. !
    # test/integration/api/root_test.rb
    !
    test "provides hypermedia URLs to top-level resources" do
    data = api :get, "/"
    !
    assert_equal 200, last_response.status
    assert_equal "https://#{GitHub.api_host_name}/user",
    data["current_user_url"]
    end
    -

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  70. !
    JSON Schema

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  71. !
    json-schema.org

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  72. !
    Validating output.

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  73. !
    /
    # Running tests:
    !
    [1/5] Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 =
    2.06 s
    1) Failure:
    Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 [/Users/
    wynn/github/github/test/integration/api/rate_limit_test.rb:67]:
    {"resources"=>{"core"=>{}, "search"=>{}}, "rate"=>{}}
    The property '#/rate' did not contain a required property of 'limit' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'remaining'
    in schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'reset' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#

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  74. !
    /
    # Running tests:
    !
    [1/5] Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 =
    2.06 s
    1) Failure:
    Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 [/Users/
    wynn/github/github/test/integration/api/rate_limit_test.rb:67]:
    {"resources"=>{"core"=>{}, "search"=>{}}, "rate"=>{}}
    The property '#/rate' did not contain a required property of 'limit' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'remaining'
    in schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'reset' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#

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  75. !
    /
    # Running tests:
    !
    [1/5] Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 =
    2.06 s
    1) Failure:
    Api::RateLimitTest#test_OAuth_app_with_custom_rate_limit_L63 [/Users/
    wynn/github/github/test/integration/api/rate_limit_test.rb:67]:
    {"resources"=>{"core"=>{}, "search"=>{}}, "rate"=>{}}
    The property '#/rate' did not contain a required property of 'limit' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'remaining'
    in schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#
    The property '#/rate' did not contain a required property of 'reset' in
    schema c1ac8566-70fa-5c34-b050-0cfa6801c1c1#

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  76. !
    Validating input.

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  77. !
    /
    # update a label
    $ curl -ni http://api.github.dev/repos/defunkt/dotjs/labels/bug \
    -X PATCH -H "Content-Type: application/json" \
    -d '{ "name":[], "color":42 }
    !
    HTTP/1.1 422 Unprocessable Entity
    !
    {
    "message": "Invalid request.\n\nExpected data to be of type \"string
    \"; value was: [].\nExpected data to be of type \"string\"; value was:
    42.",
    "documentation_url": "https://developer.github.com/v3/issues/labels/
    #update-a-label"
    }

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  78. !
    /
    # update a label
    $ curl -ni http://api.github.dev/repos/defunkt/dotjs/labels/bug \
    -X PATCH -H "Content-Type: application/json" \
    -d '{ "name":[], "color":42 }
    !
    HTTP/1.1 422 Unprocessable Entity
    !
    {
    "message": "Invalid request.\n\nExpected data to be of type \"string
    \"; value was: [].\nExpected data to be of type \"string\"; value was:
    42.",
    "documentation_url": "https://developer.github.com/v3/issues/labels/
    #update-a-label"
    }

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  79. !
    MiniTest

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  80. !
    Custom assertions

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  81. !
    test "can create a pull request" do
    auth_as @forker
    !
    data = api :post, @pub_pulls_url, {}, :input => {
    :title => "new pr",
    :body => "this is an amazing change",
    :base => "master",
    :head => "#{@forker}:ahead"
    }.to_json
    assert_equal 201, last_response.status
    assert_schema :v3, :pull_request, data
    end
    -

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  82. !
    test "can create a pull request" do
    auth_as @forker
    !
    data = api :post, @pub_pulls_url, {}, :input => {
    :title => "new pr",
    :body => "this is an amazing change",
    :base => "master",
    :head => "#{@forker}:ahead"
    }.to_json
    assert_equal 201, last_response.status
    assert_schema :v3, :pull_request, data
    end
    -

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  83. !
    test "can retrieve pull requests" do
    auth_as @owner
    !
    data = api :get, @pub_pulls_url
    assert_equal 200, last_response.status
    !
    assert_schema_for_collection \
    :v3, :pull_request_simple, data
    end
    -

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  84. !
    test "can retrieve pull requests" do
    auth_as @owner
    !
    data = api :get, @pub_pulls_url
    assert_equal 200, last_response.status
    !
    assert_schema_for_collection \
    :v3, :pull_request_simple, data
    end
    -

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  85. !
    Even more assertions

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  86. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  87. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  88. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  89. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  90. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  91. !
    test "authz list commits for pull request" do
    !
    assert_authz :get, @priv_commits_url do |check|
    check.disallows_with :not_found
    check.authorized_users @owner, @collaborator
    check.unauthorized_users :anon, @rando
    check.minimum_scopes :repo
    end
    end
    -

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  92. !
    5 lines = dozens of AuthZ assertions.

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  93. !
    But what about those critical code paths?

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  94. !
    What if you don’t trust your tests?

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  95. !
    Science 0

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  96. !
    github/dat-science
    github.com/

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  97. !
    @jbarnette

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  98. !
    @rick

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  99. !

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  100. !

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  101. !
    Safely observe alternate code paths
    for non-mutating methods
    that return a value.

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  102. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  103. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  104. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  105. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  106. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  107. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    experiment = Dat::Science::Experiment.new \
    "widget-permissions" do |e|
    !
    e.control { old_method } # old way
    e.candidate { new_method } # new way
    end
    !
    experiment.run
    end
    end
    -

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  108. Runs candidate before control 50% of the time
    Measures the duration of both behaviors
    Compares the results of both behaviors
    Swallows any exceptions raised by the candidate behavior
    Publishes findings for tracking and reporting

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  109. !
    Fancy a DSL instead?

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  110. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    science "widget-permissions" do |e|
    e.control { model.check_user(user).valid? }
    e.candidate { user.can? :read, model }
    end
    end
    end
    -

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  111. !
    require "dat/science"
    !
    class MyApp::Widget
    def allows?(user)
    science "widget-permissions" do |e|
    e.control { model.check_user(user).valid? }
    e.candidate { user.can? :read, model }
    end
    end
    end
    -

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  112. !
    Create and run.

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  113. !
    require "dat/science"
    !
    class Blog::Post
    def permalink(user)
    science "permalink" do |e|
    e.control { post[:permalink] }
    e.candidate { post.slug }
    e.comparator {|a, b| a.downcase == b.downcase }
    end
    end
    end
    -

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  114. !
    require "dat/science"
    !
    class Blog::Post
    def permalink(user)
    science "permalink" do |e|
    e.control { post[:permalink] }
    e.candidate { post.slug }
    e.comparator {|a, b| a.downcase == b.downcase }
    end
    end
    end
    -

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  115. !
    Ramping up experiments.

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  116. !
    require "dat/science"
    !
    module Myapp
    class Experiment < Dat::Science::Experiment
    def enabled?
    rand(100) < 10 # Run 10% of the time
    end
    end
    end
    -

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  117. !
    github.com/jnunemaker/flipper!

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  118. !
    require "dat/science"
    !
    module Myapp
    class Experiment < Dat::Science::Experiment
    def enabled?
    MyApp.flipper[name].enabled?
    end
    end
    end
    -

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  119. !
    Publishing results.

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  120. !
    require "dat/science"
    !
    module Myapp
    class Experiment < Dat::Science::Experiment
    def publish
    MyApp.instrument "science.#{event}", payload
    end
    end
    end
    -

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  121. !
    require "dat/science"
    !
    module Myapp
    class Experiment < Dat::Science::Experiment
    def publish
    MyApp.instrument "science.#{event}", payload
    end
    end
    end
    -

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  122. View Slide

  123. View Slide

  124. View Slide

  125. !
    Adding custom context.

    View Slide

  126. !
    require "dat/science"
    !
    class Blog::Post
    def permalink(user)
    science "permalink" do |e|
    e.context :post => post
    e.control { post[:permalink] }
    e.candidate { post.slug }
    e.comparator {|a, b| a.downcase == b.downcase }
    end
    end
    end
    -

    View Slide

  127. !
    require "dat/science"
    !
    class Blog::Post
    def permalink(user)
    science "permalink" do |e|
    e.context :post => post
    e.control { post[:permalink] }
    e.candidate { post.slug }
    e.comparator {|a, b| a.downcase == b.downcase }
    end
    end
    end
    -

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  128. Mad science.

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  129. 1 Don't try this at home

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  130. !
    module GitHub
    class Experiment < Dat::Science::Experiment
    class << self
    # Public: enable mad science mode: returns the candidate values by default
    # instead of the control.
    def mad_science=(val)
    @mad_science = val
    end
    !
    # Internal: whether or not to always run the candidate instead of the
    # control.
    def candidate_instead_of_control?
    @mad_science
    end
    end

    end
    -

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  131. !
    module GitHub
    class Experiment < Dat::Science::Experiment
    class << self
    # Public: enable mad science mode: returns the candidate values by default
    # instead of the control.
    def mad_science=(val)
    @mad_science = val
    end
    !
    # Internal: whether or not to always run the candidate instead of the
    # control.
    def candidate_instead_of_control?
    @mad_science
    end
    end

    end
    -

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  132. !
    Analyzing results.

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  133. !
    github.com/github/dat-analysis

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  134. !
    Build an analyzer to poke on results.

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  135. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

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  136. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

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  137. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

    View Slide

  138. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

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  139. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

    View Slide

  140. !
    require 'dat/analysis'
    !
    module MyApp
    class Analysis < Dat::Analysis
    def read
    Redis.rpop "dat-science.#{experiment_name}.results"
    end
    !
    def count
    Redis.llen "dat-science.#{experiment_name}.results"
    end
    !
    def cook(raw_result)
    return nil unless raw_result
    JSON.parse(raw_result)
    end
    end
    end
    -

    View Slide

  141. !
    /
    irb> a = MyApp::Analysis.new('widget-permissions')
    => #
    !
    !
    !

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  142. !
    /
    irb> a = MyApp::Analysis.new('widget-permissions')
    => #
    !
    irb> a.fetch
    => {"experiment"=>"widget-permissions", "user"=>{ ... } .... }
    !
    !

    View Slide

  143. !
    /
    irb> a = MyApp::Analysis.new('widget-permissions')
    => #
    !
    irb> a.fetch
    => {"experiment"=>"widget-permissions", "user"=>{ ... } .... }
    !
    irb> a.result
    => {"experiment"=>"widget-permissions", "user"=>{ ... } .... }
    !

    View Slide

  144. !
    /
    irb> a.result.control
    => {"duration"=>12.307, "exception"=>nil, "value"=>false}
    !
    !
    !

    View Slide

  145. !
    /
    irb> a.result.control
    => {"duration"=>12.307, "exception"=>nil, "value"=>false}
    !
    irb> a.result.candidate
    => {"duration"=>12.366999999999, "exception"=>nil, "value"=>true}
    !

    View Slide

  146. !
    Handling change (

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  147. !
    New formats

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  148. !
    Features evolve. URLs don’t have to.

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  149. !
    /
    [
    "[email protected]",
    "[email protected]"
    ]
    curl -n http://api.github.com/user/emails

    View Slide

  150. !
    /
    [
    "[email protected]",
    "[email protected]"
    ]
    curl -n http://api.github.com/user/emails

    View Slide

  151. !
    /
    curl -n http://api.github.com/user/emails \
    -H "Accept: application/vnd.github.v3"
    [
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    },
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    }
    ]

    View Slide

  152. !
    /
    curl -n http://api.github.com/user/emails \
    -H "Accept: application/vnd.github.v3"
    [
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    },
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    }
    ]

    View Slide

  153. !
    /
    curl -n http://api.github.com/user/emails \
    -H "Accept: application/vnd.github.v3"
    [
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    },
    {
    "email": "[email protected]",
    "primary": false,
    "verified": true
    }
    ]

    View Slide

  154. !
    Media types

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  155. !
    curl https://api.github.com/users/technoweenie -I
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3

    View Slide

  156. !
    curl https://api.github.com/users/technoweenie -I
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3

    View Slide

  157. !
    curl https://api.github.com/users/technoweenie -I
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3

    View Slide

  158. !
    curl https://api.github.com/users/technoweenie -I
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.full+json"
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3; param=full; format=json

    View Slide

  159. !
    curl https://api.github.com/users/technoweenie -I
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.full+json"
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3; param=full; format=json

    View Slide

  160. !
    curl https://api.github.com/users/technoweenie -I
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.full+json"
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3; param=full; format=json

    View Slide

  161. !
    curl https://api.github.com/users/technoweenie -I
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.full+json"
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3; param=full; format=json
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.beta.full+json"
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.beta; param=full; format=json

    View Slide

  162. !
    curl https://api.github.com/users/technoweenie -I
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.full+json"
    /
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.v3; param=full; format=json
    curl https://api.github.com/users/technoweenie -I \
    -H "Accept: application/vnd.github.beta.full+json"
    HTTP/1.1 200 OK
    X-GitHub-Media-Type: github.beta; param=full; format=json

    View Slide

  163. !
    @jasonrudolph
    “Beta like you mean it.”

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  164. !
    Media types as beta code words.

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  165. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }

    View Slide

  166. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }

    View Slide

  167. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }

    View Slide

  168. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }
    curl https://api.github.com/the/new/shiny \
    -H "Accept: application/vnd.github.new-shiny-preview"
    HTTP/1.1 200 OK

    View Slide

  169. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }
    curl https://api.github.com/the/new/shiny \
    -H "Accept: application/vnd.github.new-shiny-preview"
    HTTP/1.1 200 OK

    View Slide

  170. !
    curl https://api.github.com/the/new/shiny
    /
    HTTP/1.1 415 Unsupported Media Type
    !
    {
    "message": "Unsupported 'Accept' header: github.v3."
    }
    curl https://api.github.com/the/new/shiny \
    -H "Accept: application/vnd.github.new-shiny-preview"
    HTTP/1.1 200 OK
    acknowledge API is a preview release

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  171. !
    Client testing

    View Slide

  172. View Slide

  173. !
    octokit.github.com

    View Slide

  174. !
    github.com/octokit/octokit.rb

    View Slide

  175. !
    github.com/rspec/rspec

    View Slide

  176. !
    describe Octokit::Client do
    !
    describe ".rate_limit" do
    it "makes a response if there is no last response" do
    client = Octokit::Client.new
    VCR.use_cassette "rate_limit" do
    rate = client.rate_limit
    !
    expect(rate.limit).to be_kind_of Fixnum
    expect(rate.remaining).to be_kind_of Fixnum
    end
    end # .rate_limit
    end

    -

    View Slide

  177. !
    describe Octokit::Client do
    !
    describe ".rate_limit" do
    it "makes a response if there is no last response" do
    client = Octokit::Client.new
    VCR.use_cassette "rate_limit" do
    rate = client.rate_limit
    !
    expect(rate.limit).to be_kind_of Fixnum
    expect(rate.remaining).to be_kind_of Fixnum
    end
    end # .rate_limit
    end

    -

    View Slide

  178. !
    describe Octokit::Client do
    !
    describe ".rate_limit" do
    it "makes a response if there is no last response" do
    client = Octokit::Client.new
    VCR.use_cassette "rate_limit" do
    rate = client.rate_limit
    !
    expect(rate.limit).to be_kind_of Fixnum
    expect(rate.remaining).to be_kind_of Fixnum
    end
    end # .rate_limit
    end

    -

    View Slide

  179. !
    describe Octokit::Client do
    !
    describe ".rate_limit" do
    it "makes a response if there is no last response" do
    client = Octokit::Client.new
    VCR.use_cassette "rate_limit" do
    rate = client.rate_limit
    !
    expect(rate.limit).to be_kind_of Fixnum
    expect(rate.remaining).to be_kind_of Fixnum
    end
    end # .rate_limit
    end

    -

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  180. !
    Record live API requests
    to play back later.
    Is it live, or is it Memorex®

    View Slide

  181. !
    github.com/vcr/vcr

    View Slide

  182. !
    Environment smoke tests

    View Slide

  183. !
    /
    rm -rf spec/cassettes

    ~/.coral/repos/octokit.rb@octokit master

    ~/.coral/repos/octokit.rb@octokit master*

    View Slide

  184. !
    /
    rm -rf spec/cassettes

    ~/.coral/repos/octokit.rb@octokit master
    OCTOKIT_API_ENDPOINT="https://rails5.github.com" rspec

    ~/.coral/repos/octokit.rb@octokit master*
    .................................................
    ..............F..................................
    ........................FFF......................
    ...................F.............................
    ........F........................................
    .................................................
    .....................F........F..................

    View Slide

  185. !
    measure change &
    minimize change '
    handle change (
    At GitHub, we
    so we can
    in order to

    View Slide

  186. !
    One more thing.

    View Slide

  187. !
    github.com/interagent

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  188. !
    410 Gone

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