def bootstrap():
    """ initialize remote host environment (virtualenv, deploy, update) """
    require('root', provided_by=('staging', 'production'))
    run('mkdir -p %(root)s' % env)
    run('mkdir -p %s' % os.path.join(env.home, 'www', 'log'))
    create_virtualenv()
    deploy()
    update_requirements()
 
 
def create_virtualenv():
    """ setup virtualenv on remote host """
    require('virtualenv_root', provided_by=('staging', 'production'))
    args = '--clear --distribute'
    run('virtualenv %s %s' % (args, env.virtualenv_root))
 
 
def deploy():
    """ rsync code to remote host """
    require('root', provided_by=('staging', 'production'))
    if env.environment == 'production':
        if not console.confirm('Are you sure you want to deploy production?',
                               default=False):
            utils.abort('Production deployment aborted.')
    extra_opts = '--omit-dir-times'
    rsync_project(
        env.root,
        exclude=RSYNC_EXCLUDE,
        delete=True,
        extra_opts=extra_opts,
    )
    touch()
 
 
def update_requirements():
    """ update external dependencies on remote host """
    require('code_root', provided_by=('staging', 'production'))
    requirements = os.path.join(env.code_root, 'requirements')
    with cd(requirements):
        cmd = ['pip install']
        cmd += ['-E %(virtualenv_root)s' % env]
        cmd += ['--requirement %s' % os.path.join(requirements, 'apps.txt')]
        run(' '.join(cmd))