This document compares and contrasts two tools for deploying Python web applications to remote servers: Hostout and Silverlining. Hostout uses Fabric and buildout to replicate a local development environment across multiple servers. It provides a modular approach that allows customization through additional recipes and fabric files. Silverlining takes a more "batteries included" approach by creating a standard application layout and managing dependencies, code installation, and deployment through simple commands. While both tools aim to simplify deployment, Hostout offers more flexibility through its buildout-based approach but with increased complexity, while Silverlining provides a more standardized workflow out of the box at the cost of customizability. The document discusses the tradeoffs between the two in

1. Oops! I deployed it again
New ways to get your app in the cloud Dylan Jay

2. You've written a web app
And now you need a host

3. We want it to be easy

4. We want flexibility

5. We want it to be cheap

6. Options
Type Providers Flexibility (Easy) Scalability
Shared Few
e.g. Webfaction
($14)
Limited Choice
(Control Panel)
None
AppEngine One
Google (Free)
No Choice
(Launcher)
Built in
VPS Lots
e.g. Slicehost ($20)
Unlimited choice
(DIY)
DIY
Cloud Few
e.g. Rackspace ($11)
Unlimited choice
(DIY)
DIY

7. Can you have your cake
and eat it to?

8. Hostout (Fabric, buildout)
&
Silverlining

9. Code under development

10. Push vs Pull

11. Fabric
<< fabfile.py >>
from fabric import api
def host_type():
api.run('uname -s')
$ fab -H localhost,linuxbox host_type

12. Buildout Workflow
Get the “buildout”
$ python bootstrap.py
$ bin/buildout
$ bin/myinstalledscript
… add recipes to buildout.cfg from pypi …
$ bin/buildout

13. Building myapp
$ bin/buildout
$ bin/paster serve src/myapp/myapp.ini

14. Useful recipes
● zc.recipe.egg – download eggs and create
scripts
● collective.recipe.command – run shell
commands
● collective.recipe.template – make config files
from templates
● zc.recipe.cmmi – compile, make, install stuff
● isotoma.recipe.apache – or any other useful
shortcuts
● mr.developer – manage source control

15. Hostout
Is
a buildout recipe
to replicate a local buildout
to many hosts
(using fabric)

16. Why document it when you can code it?

17. Basic Hostout
[buildout]
parts = host1
[host1]
recipe = collective.hostout
host = 127.0.0.1:10022
fabfiles = fabfile.py
option1 = buildout
user = root
password = root
path = /var/host1

18. Command line
$> bin/hostout host1 host_type
$> bin/hostout host1 host2 host_type echo
hello

19. Share your command
< setup.py >
entry_points = {'zc.buildout': ['default =pkg:Recipe',],
'fabric': ['fabfile = pkg.fabfile']
},
[host1]
recipe = collective.hostout
extends = pkg

20. Built in commands
● Run
● Sudo
● Deploy
● Predeploy
– Bootstrap – platform dependent
● setupusers
● setowners
● Uploadeggs
● Uploadbuildout
● Buildout
● Postdeploy

21. Releasing eggs
1 hostoutversions.cfg during buildout
2 sdist with md5 for all develop eggs
3 fabric.api.put all hashed eggs (if needed)
1 Direct to egg cache
4 deployed.cfg with hashed versions pinned
5 Upload zip of buildout + includes
6 fabric.api.run( bin/buildout -c deployed.cfg )

22. Hostout
● Get a “production” buildout
● To your develop.cfg buildout add...
[myhost]
recipe = collective.hostout
extends = hostout.cloud hostout.ubuntu
hosttype = rackspace
key = myaccount
secret = myapikey
buildout = production.cfg
● $ bin/buildout
● $ bin/hostout myhost deploy

23. Hostout is modular
● collective.hostout
● Deploys buildout to any posix host. Needs IP and
password
● hostout.ubuntu
● bootstraps ubuntu host for buildout
● hostout.cloud
● Creates node ready to be bootstrapped
● fabfiles = myfabfile.py – add your own

24. Suggested layout
● buildout.cfg (extends = config/deploy.cfg config/devel.cfg)
● config/
● base.cfg (extends = base.cfg)
● devel.cfg (extends = base.cfg)
● prod.cfg (extends = base.cfg)
● deploy.cfg (extends = base.cfg)
– [host1]
– buildout = production.cfg
– parts = instance1

25. User model
[host1]
user = {initial sudo user}
buildout-user = {owns buildout files + pw-less
login}
effective-user = {owns var dir}
buildout-group = {group owns both}

26. Extra Options
● include = {files to include in buildout zip}
● parts = {override parts}
● sudo-parts = {sudo bin/buildout install …}
● pre-commands = {shell to sudo before}
● post-commads = {shell to sudo after}
● path = {location of buildout}

27. Deployment Hooks
def predeploy():
domystuff
api.env.hostout.super.predeploy()
● Calls that are overridable
– api.env.hostout.callmycommand()

28. hostout.supervisor
● Pre and post deployment stop and start
● bin/hostout host status
● bin/hostout host supervisorboot
● bin/hostout host start/stop/restart

29. hostout.cloud
● bin/hostout host create
● bin/hostout host destroy
● Predeploy hook to create if needed
[host1]
extends =
hostout.cloud
hostout.ubuntu
hostout.supervisor
hosttype = rackspace
hostname = ploneplonk
key = ${keys:rackspace_key}
secret = ${keys:rackspace_secret}

30. Gotchas
● Eggs must be releasable. Ie need setuptools-git
etc
● All files must be checked in locally
● Interactive commands get stuck

33. $ bin/hostout host deploy

34. Silverlining
● By Ian Bicking
● Create app layout/dir
● $ silver init myapp
● Install dependencies into dir
● $ cd app; bin/easy_install repoze.bfg
● Install your code into dir
● $ bin/python src/myapp/setup.py develop

35. Silverlining II
● Configure it
● Edit app.ini: runner = src/myapp/myapp.ini
● Create host
● $ silver create-node myhost
● $ silver setup-node myhost
● Deploy (rsync)
● $ silver update myapp --node myhost

36. Hostout vs. Silverlining
● Many deployers
● Checkin. Checkout. Buildout. deploy
● Hostout uses fabric
● Cross platform but more dependencies (pycrypto)
● Hostout is modular
● Package your own fabfiles to help others deploy
● Hostout is flexible – helps professionals
● Buildout is powerful. No limit to building/installing.
NoSQL etc.
● Buildout shares dl code

37. Silverlining vs. Hostout
● Silverlining is batteries included
● You don't need a production buildout
● Silverlining is “known” target platform
● means less variables to go wrong
● Familiar workflow
● Commandline vs cfg.

38. Thanks
● Dylan Jay
● http://www.pretaweb.com
● twitter: djay75
● pyconau@dylanjay.com
● Know plone, syd admin or pywebdev? - we're
hiring

39. Photo Credits
http://www.flickr.com/photos/benheine/4613609067/sizes/l/in/set-72157622547905358/
http://www.flickr.com/photos/stevedave/3444248057/sizes/o/
http://www.flickr.com/photos/rkbcupcakes/3409724942/sizes/o/
http://www.flickr.com/photos/irrational_cat/517564258/