Heroku Under The Hood - Django Under The Hood 2015

Transcript

1. Heroku Under the Hood
   workshop
   

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2. Agenda
   1. Performance tuning and dyno sizing
   2. Buildpacks
   3. app.json and the Heroku button
   4. Platform API
   

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3. Performance tuning
   

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4. Performance basics
   Which WSGI server should I use?
   Recommendations: gunicorn, uWSGI
   Worth trying: waitress, twisted
   Not even once: runserver
   How many workers should I run?
   Start with WEB_CONCURRENCY
   Tune appropriately (more on this later)
   How should I serve static assets?
   Small scale: use Whitenoise
   Large scale, option A: S3 + CDN
   Large scale, option B: Whitenoise + CDN
   

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5. Dyno types
   Type RAM Compute Cost
   Free / Hobby 512 MB 1-4x $0 / $7
   Standard-1X 512 MB 1-4x $25
   Standard-2X 1 GB 2x - 4x $50
   Performance-M 2.5 GB 12x $250
   Performance-L 14 GB 50x $500
   

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6. Optimizing dyno types
   Assumption: your application is RAM-bound.
   Recommendation: optimize for cost per process.
   You’ll need to measure:
   RAM per process
   number of required processes
   Math:
   cost_per_process = (dyno_ram / process_ram) * dyno_cost
   H/T: https://medium.com/swlh/running-a-high-traffic-rails-app-on-heroku-s-performance-dynos-d9e6833d34c
   

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7. Example 1
   Dyno
   Processes /
   dyno
   Required #
   of dynos
   Total cost Cost / process
   1X 4 5 $125 $6
   2X 8 3 $150 $8
   P-M 21 1 $250 $13
   P-L 119 1 $500 $25
   RAM per process: 120
   Total processes: 20
   

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8. Example 2
   Dyno
   Processes /
   dyno
   Required #
   of dynos
   Total cost Cost / process
   1X 1 60 $1,500 $25
   2X 2 30 $1,500 $25
   P-M 5 12 $3,000 $50
   P-L 31 2 $1,000 $17
   RAM per process: 450
   Total processes: 60
   

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9. Making measurements
   1. Observe memory performance:
   log-runtime-metrics
   Heroku Dashboard
   Librato
   2. Load test
   Siege 

   https://www.joedog.org/siege-home/
   Bees with Machine Guns 

   https://github.com/newsapps/beeswithmachineguns
   Load testing addons 

   https://elements.heroku.com/addons#testing
   

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10. Exercise 1:
    performance tuning
    A. What’s your RAM per process?
    B. What’s your number of required processes?
    C. What’s your optimal dyno formation?
    

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11. Buildpacks
    

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12. $ git push heroku master
    ...
    -----> Python app detected
    -----> Installing runtime (python-2.7.10)
    -----> Installing dependencies using pip
    ...
    What’s a buildpack?
    

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13. How buildpacks work
    bin/detect — will this buildpack build this app?
    bin/compile — compile source into app
    bin/release — emit default config/addons
    

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14. Python buildpack
    https://github.com/heroku/heroku-buildpack-python
    

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15. Other interesting buildpacks
    Conda
    https://github.com/kennethreitz/conda-buildpack
    Null
    https://github.com/ryandotsmith/null-buildpack
    pgbouncer
    https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-pgbouncer
    nginx
    https://elements.heroku.com/buildpacks/ryandotsmith/nginx-buildpack
    

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16. Multiple buildpacks
    Use cases:
    nginx / pgbouncer
    asset collection via Gulp/Grunt/etc.
    …?
    $ heroku buildpacks
    === aqueous-shore-5792 Buildpack URL
    heroku/python
    $ heroku buildpacks:add --index 2 heroku/nodejs
    Buildpack added. Next release on aqueous-shore-5792 will use:
    1. heroku/python
    2. heroku/nodejs
    Run `git push heroku master` to create a new release using these buildpacks.
    

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17. Exercise 2:
    try out multi-buildpack
    A. Try out nginx or pgbouncer. 

    Do they improve performance?
    B. Try a Node asset manager:

    https://github.com/beaugunderson/django-gulp
    

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18. app.json, 

    Heroku buttons, 

    and Pipelines
    

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19. $ cat app.json
    {
    "name": "Appointment Reminders (Django)",
    "description": "Appointment Reminders in Django with Twilio",
    "repository": "https://github.com/atbaker/appointment-reminders-django",
    "addons": [
    "heroku-postgresql:hobby-dev",
    "redistogo:nano"
    ],
    "env": {
    "TWILIO_ACCOUNT_SID": {
    "description": "Your Twilio account secret ID",
    "value": "enter_your_account_sid_here",
    "required": true
    },
    ...
    }
    }
    app.json
    

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20. [![Deploy](https://www.herokucdn.com/deploy/
    button.png)](https://heroku.com/deploy?
    template=https://github.com/atbaker/appointment-
    reminders-django)
    template=https://github.com/atbaker/appointment-
    reminders-django">
    button.png">
    
    Heroku button
    

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21. Pipelines / PR apps
    Live demo
    (yipes)
    

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22. Exercise 3:
    app.json / PR apps
    A. Create an app.json (and Heroku button?) for your app.
    B. Try out pull request apps.
    

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23. Platform API
    https://devcenter.heroku.com/articles/platform-api-quickstart
    https://devcenter.heroku.com/articles/platform-api-reference
    

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24. >>> import netrc, requests, json
    >>> token = netrc.netrc().hosts['api.heroku.com'][2]
    >>> h = requests.session()
    >>> h.headers['Authorization'] = 'Bearer ' + token
    >>> h.headers['Accept'] = 'application/vnd.heroku+json; version=3'
    >>> h.headers['Content-Type'] = 'application/json'
    >>> formation = h.get('https://api.heroku.com/apps/NAME/formation').json()
    >>> {f['type']: f['quantity'] for f in formation}
    {'web': 1, 'worker': 0}
    >>> payload = {'quantity': 4, 'size': 'standard-1X'}
    >>> h.patch('https://api.heroku.com/apps/NAME/formation/web',
    data=json.dumps(payload))
    >>> formation = h.get('https://api.heroku.com/apps/NAME/formation').json()
    >>> {f['type']: f['quantity'] for f in formation}
    {'web': 4, 'worker': 0}
    Intro
    

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25. Authentication
    Authentication uses bearer tokens:
    For local dev and/or fooling around, reading a token from .netrc is fine.
    Better: direct authentication with token exchange:
    Best: proper use of OAuth + scopes: 

    https://devcenter.heroku.com/articles/oauth
    >>> h.post('https://api.heroku.com/oauth/authorizations',
    ... data=json.dumps({'description': 'demo auth'})).json()
    {'access_token': {'expires_in': None,
    'id': '4d6e04f0-693b-4118-bb9b-646e723ff7fa',
    'token': ‘4a1637b4-9bc8-4ad9-8747-43ec7c744621'},
    ...}
    >>> h.headers['Authorization'] = 'Bearer ' + token
    

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26. Build & Slug APIs
    Deploy to Heroku without git push heroku master!
    To build without releasing, use a build app and copy slugs:

    https://devcenter.heroku.com/articles/platform-api-copying-slugs
    You can also create slugs from scratch: 

    https://devcenter.heroku.com/articles/platform-api-deploying-slugs
    >>> source = h.post('https://api.heroku.com/apps/aqueous-shore-5792/sources').json()
    >>> requests.put(source['source_blob']['put_url'], data=open('foo.tgz').read())
    >>> payload = {'source_blob': {'url': source['source_blob']['get_url'],
    ... 'version': 'abcd1234'}}
    >>> build = h.post('https://api.heroku.com/apps/aqueous-shore-5792//builds', 

    data=json.dumps(payload)).json()
    

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27. Exercise 4:
    platform API
    A. Build an auto-scaler.
    B. Build an alternate deploy flow.
    C. Re-create pull-request apps (!)
    

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