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How to bootstrap a startup using Django

philw
July 05, 2012

How to bootstrap a startup using Django

We show the lessons learned developing Gidsy.com on a Django stack in the last year.

The topics are:
* how we organizes teams
* automize our infrastructure
* automize information flow
* which external services we use
* how we do releases
* deploying
* monitoring
* caching strategy and invalidation

philw

July 05, 2012
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Transcript

  1. Why Django is a good choice Proven technology by similar

    use cases Stable APIs in a well-de ned release process Good documentation with focus on prose Huge community of 3rd party components
  2. API Highly customizable Web API library Hooks for auth, throtteling,

    caching, etc. Backbone.js compatible Tastypie
  3. Task queues Async code execution, cronjobs Thumbnails, search index updates,

    caching, etc. Collect stats without blocking Celery
  4. Caching Periodic cache refreshing for high traffic sites Fragment caching

    with dates and cache version Cache warming during deployment Memcache
  5. Work ow Main branch is always deployable Development happens in

    feature branches Code reviews via pull requests Shared responsibility
  6. Testing Separation of fast and slow tests Full test suite

    via Jenkins, soon Travis CI Fast tests locally via tox
  7. Scaling up Each server downloads dependencies External services could be

    down (PyPI, Github, ...) Which server is in charge of migrations, collectstatic?
  8. Deploy system Builds are virtualenvs Atomic and orchestrated releases Collectstatic,

    migrate & other commands centralized Web interface for deploying, rollback Keeps information on who deployed what Will be open sourced
  9. Deploy system Hipchat (or IRC) New Relic Deploy Noti es

    the team and services when deploys happen
  10. Provisioning servers Follows DRY principle Chef/Puppet/Salt Documents infrastructure and change

    Place to share and store secure data Roles can be on many or one servers Challenge is separating deployment from app
  11. { "name": "staging", "cookbook_versions": { "gidsy_common": "0.0.3" }, "override_attributes": {

    "gidsy": { "DISABLE_QUERYSET_CACHE": "False", "COMPRESS_ENABLED": "True", "EMAIL_HOST_PASSWORD": "*****", "BROKER_URL": "redis://14.21.12.18:6379/5", "HAYSTACK_URL": "http://10.24.15.21:9200/" }, "databases": { "gidsy": "host=11.21.17.34 dbname=gidsy", }, }, ... "json_class": "Chef::Environment", "chef_type": "environment" } Staging Environment { "run_list": [ "recipe[ssh_config]", "recipe[sudo]", "recipe[users::sysadmins]", "recipe[pg_bouncer]", "recipe[nginx::default]", "recipe[gidsy_common]", "recipe[gidsy_web]", "recipe[new_relic]", "recipe[hostname]", "recipe[papertrail]" ], .... "name": "web", "json_class": "Chef::Role" } Chef con guration Chef Environment { "run_list": [ "recipe[ssh_config]", "recipe[sudo]", "recipe[users::sysadmins]", "recipe[pg_bouncer]", "recipe[gidsy_common]", "recipe[gidsy_celery]", "recipe[new_relic]", "recipe[hostname]", "recipe[papertrail]" ], .... "name": "celery", "json_class": "Chef::Role" } Chef Role Chef Role
  12. Provisioning servers knife ec2 server create -N staging-web1 -r "role[web]"

    -G staging-web -E staging -I ami-95dde2e1 -f m1.small -Z eu-west-1a Starting a new web server using chef knife ec2 server delete i-1234567 Deleting a web server knife ssh “role:web” “sudo chef-client” Running commands on all web servers
  13. Working with cloud servers ec2-ssh ssh [email protected] -i ~/.ssh/gidsy.pem before

    ec2-ssh phil@production-web2 after Simple syntax Name never changes, unlike url on reboot of server
  14. Operations, metrics, maintenance Log everything you could need for debugging

    If you deploy often then you need immediate feedback Use services if you can (Mixpanel, NewRelic, Librato, Papertrail, Pagerduty) Show the metrics on a screen in the office
  15. Operations, metrics, maintenance Push data to the services (mixpanel, librato,

    log, db) App-metrics -> librato or mixpanel Logging -> papertrail -> librato Extended it to send one metric to many backends django-app-metrics
  16. Operations, metrics, maintenance Papertrail log of celery tasks sent Logs

    can be graphed by librato Set alerts on logs that send to pagerduty/hipchat/webhook...
  17. Librato/Graphite Operations, metrics, maintenance Logs can be graphed by librato

    Set alerts on logs that send to pagerduty/hipchat/webhook...
  18. Things we learned Only scale when you need to, but

    be prepared Be pragmatic, use the best tool to do the job Automate as much as you can Continuous Integration and Continuous Deployment Make routine tasks as easy as possible Use services Display metrics To bootstrap your startup quickly