Bootstrap a Flask project on Ubuntu Precise, with Puppet, Vagrant and Fabric. (For latest version, see https://github.com/dansimau/flask-bootstrap)

.gitignore

*~
*.pyc
.vagrant
venv

__init__.py

from flask import Flask

app = Flask(__name__)
app.config.from_pyfile('%s/config/default.cfg' % app.root_path)
app.config.from_envvar('FLASK_CONFIG')

__init__.py

from fabric.decorators import task

import app
import db
import puppet
import virtualenv

@task
def build():
    """Execute build tasks for all components."""
    virtualenv.build()
    db.build()

README.md

Quick start

After installing Vagrant, create and boot the VM:

vagrant up

SSH to the VM:

vagrant ssh

Run your app:

fab app.run

Notes

After initial boot, you should freeze the newly-installed pip packages at their versions:

pip freeze > requirements.txt

README.md

Run fab db.build to init alembic in this directory.

app.py

from fabric.decorators import task
from fabric.context_managers import settings
from utils import do

@task
def run():
    """Start app in debug mode (for development)."""
    do('export FLASK_CONFIG=$PWD/app/config/dev.cfg && venv/bin/python ./run.py')

config.py

remote_path = ''

branches = {
    'staging': {
        'hosts': ''
    },
    'uat': {
        'hosts': ''
    },
    'production': {
        'hosts': ''
    },
}

db.py

from fabric.decorators import task
from fabric.context_managers import settings, hide
from fabric.colors import cyan
from utils import do

config_file_path = 'db/alembic.ini'

@task
def build():
    """Initialise and migrate database to latest version."""
    print(cyan('\nUpdating database...'))
    with settings(hide('warnings'), warn_only=True):
        do('venv/bin/alembic -c %s init db/postgresql' % config_file_path)

default.cfg

SECRET_KEY = ''

dev.cfg

DEBUG = True

init.pp

class fabric {
  package { 'Fabric':
    provider => 'pip',
    ensure   => 'present',
  }
}

init.pp

class git {
  package { 'git':
    ensure => 'installed',
  }
}

init.pp

class postgresql {
  # postgresql-dev required for Python's psycopg2
  package { [ 'postgresql', 'postgresql-server-dev-all' ]:
    ensure => 'installed',
  }
  service { 'postgresql':
    ensure  => running,
    require => Package[postgresql],
  }
}

init.pp

class python {
  include python::modules
  package { 'python':
    ensure => installed,
  }
}

init.pp

class vagrant {
  line { 'line-venv-activate':
    ensure => present,
    file   => '/home/vagrant/.bashrc',
    line   => 'cd /vagrant && . venv/bin/activate',
  }
}

line.pp

define line($file, $line, $ensure = 'present') {
  case $ensure {
    default : { err ( "unknown ensure value ${ensure}" ) }
    present: {
      exec { "/bin/echo '${line}' >> '${file}'":
        unless => "/bin/grep -qFx '${line}' '${file}'"
      }
    }
    absent: {
      exec { "/bin/grep -vFx '${line}' '${file}' | /usr/bin/tee '${file}' >/dev/null 2>&1":
        onlyif => "/bin/grep -qFx '${line}' '${file}'"
      }
    }
    uncomment: {
      exec { "/bin/sed -i -e'/${line}/s/#\\+//' '${file}'":
        onlyif => "/bin/grep '${line}' '${file}' | /bin/grep '^#' | /usr/bin/wc -l"
      }
    }
    comment: {
      exec { "/bin/sed -i -e'/${line}/s/\\(.\\+\\)$/#\\1/' '${file}'":
        onlyif => "/usr/bin/test `/bin/grep '${line}' '${file}' | /bin/grep -v '^#' | /usr/bin/wc -l` -ne 0"
      }
    }
  }
}

modules.pp

class python::modules {
  package { [ 'python-virtualenv', 'python-dev', ]:
    ensure => 'installed',
  }
}

puppet.py

from fabric.api import env
from fabric.decorators import task
from fabric.colors import cyan
from utils import do

@task
def check():
    """Syntax check on Puppet config."""
    print(cyan('\nChecking puppet syntax...'))
    do('find puppet -type f -name \'*.pp\' |xargs puppet parser validate')

@task
def apply():
    """Apply Puppet manifest."""
    print(cyan('\nApplying puppet manifest...'))
    do('sudo puppet apply --modulepath=puppet/modules/ puppet/manifests/standalone.pp' % env)

requirements.txt

alembic
Flask
Flask-SQLAlchemy
Flask-Assets
psycopg2

run.py

#!/usr/bin/env python
from app import app
app.run(host='0.0.0.0')

standalone.pp

#
# Standalone manifest - for dev Vagrant box.
#

import 'lib/*.pp'

include fabric
include git
include postgresql
include python
include vagrant

utils.py

from fabric.api import require, env, local, run as fab_run
from fabric.utils import abort
import config

def do(*args, **kwargs):
    """
    Runs command locally or remotely depending on whether a remote host has
    been specified.
    """
    if env.host_string:
        with settings(cd(config.remote_path)):
            return fab_run(*args, **kwargs)
    else:
        return local(*args, **kwargs)

def require_host():
    """
    Forces a remote host to be set, automatically detecting it from the current
    git branch if possible.
    """
    if not env.host_string:

        # Detect current branch from git, based on config
        branch = local('git symbolic-ref -q HEAD', capture=True).split('/')[2]

        # Ensure the current branch matches up to a known branch
        if branch in config.branches:
            env.branch = branch

        require('branch')

        # Manually set host_string variable
        env.host_string = env.branches[branch]['hosts']

    require('host_string')

Vagrantfile

# -*- mode: ruby -*-
# vi: set ft=ruby :

Vagrant::Config.run do |config|
  # All Vagrant configuration is done here. The most common configuration
  # options are documented and commented below. For a complete reference,
  # please see the online documentation at vagrantup.com.

  # Every Vagrant virtual environment requires a box to build off of.
  config.vm.box = "precise64"

  # The url from where the 'config.vm.box' box will be fetched if it
  # doesn't already exist on the user's system.
  config.vm.box_url = "http://files.vagrantup.com/precise64.box"

  # Boot with a GUI so you can see the screen. (Default is headless)
  # config.vm.boot_mode = :gui

  # Assign this VM to a host-only network IP, allowing you to access it
  # via the IP. Host-only networks can talk to the host machine as well as
  # any other machines on the same network, but cannot be accessed (through this
  # network interface) by any external networks.
  config.vm.network :hostonly, "172.16.1.2"

  # Assign this VM to a bridged network, allowing you to connect directly to a
  # network using the host's network device. This makes the VM appear as another
  # physical device on your network.
  # config.vm.network :bridged

  # Forward a port from the guest to the host, which allows for outside
  # computers to access the VM, whereas host only networking does not.
  config.vm.forward_port 5000, 5000

  # Share an additional folder to the guest VM. The first argument is
  # an identifier, the second is the path on the guest to mount the
  # folder, and the third is the path on the host to the actual folder.
  config.vm.share_folder("v-root", "/vagrant", ".", :nfs => true)

  # Update apt
  config.vm.provision :shell, :inline => "aptitude -q2 update"

  # Enable provisioning with Puppet stand alone.  Puppet manifests
  # are contained in a directory path relative to this Vagrantfile.
  # You will need to create the manifests directory and a manifest in
  # the file base.pp in the manifests_path directory.
  config.vm.provision :puppet do |puppet|
    puppet.manifests_path = "puppet/manifests"
    puppet.module_path = "puppet/modules"
    puppet.manifest_file  = "standalone.pp"
  end

  # Application provision
  config.vm.provision :shell, :inline => "cd /vagrant && stdbuf -o0 fab build; exit 0"

end

virtualenv.py

from fabric.decorators import task
from fabric.context_managers import settings, hide
from fabric.colors import cyan, red
from fabric.utils import abort
from utils import do

@task
def build():
    """Build or update the virtualenv."""
    with settings(hide('stdout')):
        print(cyan('\nUpdating venv, installing packages...'))
        do('[ -e venv ] || virtualenv venv --no-site-packages')
        # annoyingly, pip prints errors to stdout (instead of stderr), so we
        # have to check the return code and output only if there's an error.
        with settings(warn_only=True):
            pip = do('venv/bin/pip install -r requirements.txt', capture=True)
        if pip.failed:
            print(red(pip))
            abort("pip exited with return code %i" % pip.return_code)

I think fabfile/app.py should be...

from fabric.decorators import task
from fabric.context_managers import settings
from utils import do


@task
def run():
    """Start app in debug mode (for development)."""
    do('export FLASK_CONFIG=$PWD/app/config/dev.cfg && venv/bin/python ./app.py')

I could be very wrong though.

@drcongo: The purpose of fab app.run is to invoke run.py which launches the built-in Flask development server. There is no app.py to run.

It would be nice to eliminate run.py altogether, though.