fabfile - simple django app deploy

fabfile.py

import os
from fabric.api import run, cd, env, abort
from fabric.contrib.console import confirm
from fabric.context_managers import prefix
from fabric.tasks import Task

env.hosts = ['sample@example.com']

env.settings = ['staging', 'production']

env.dirs = {
    'staging': '~/websites/dev.sample.com/',
    'production': '~/websites/sample.com/'
}

env.source_dir = 'sample'
env.django_project_dir = 'src/sample'
env.venv_dir = 'sample_venv'

env.apps = {
    'staging': 'staging_sample_app',
    'production': 'production_sample_app'
}

env.branches = {
    'staging': 'default',
    'production': 'production'
}

class DeployTask(Task):
    name = 'deploy'

    def run(self, settings='staging'):
        self.settings = settings
        self.check_settings() 
        with self.virtualenv():
            with self.cd_django_project():
                self.dump_db() 
                old_revision = self.current_revision()
                self.pull_and_update_code()
                self.update_venv()
                self.run_tests(old_revision)
                self.update_static_files()
                self.update_db()
                self.restart_app()

    def virtualenv(self):
        VENV_ABSOLUTE_PATH = os.path.join(env.dirs[self.settings], env.venv_dir)
        return prefix('source {0}/bin/activate'.format(VENV_ABSOLUTE_PATH))

    def cd_django_project(self):
        DJANGO_PROJECT_PATH = os.path.join(env.dirs[self.settings], env.source_dir, env.django_project_dir)
        return cd(DJANGO_PROJECT_PATH)

    def check_settings(self):
        if self.settings not in env.settings:
            abort('Invalid settings.')
        if self.settings == 'production' and not confirm('Do you realy want to deploy to production?'):
            abort('Aborting!')

    def dump_db(self):
        DUMP_FILE_PATH = os.path.join(env.dirs[self.settings], 'deploy_dump.json')
        run('./manage.py dumpdata --settings=settings.{0} > {1}'.format(self.settings, DUMP_FILE_PATH))

    def current_revision(self):
        return run('hg parent --template "{node}"')

    def pull_and_update_code(self):
        run('hg pull'.format(env.branches[self.settings]))
        run('hg update {0}'.format(env.branches[self.settings]))

    def update_venv(self):
        REQUIREMENTS_FILE_PATH = os.path.join(env.dirs[self.settings], env.source_dir, 'requirements.txt')
        run('pip install -q -r {0}'.format(REQUIREMENTS_FILE_PATH))

    def run_tests(self, old_revision):
        result = run('./manage.py test --settings=settings.local')
        if result.failed:
            run('hg update -r {0}'.format(old_revision))
            abort('Tests faild.')

    def update_static_files(self):
        run('./manage.py synccompress --settings=settings.{0}'.format(self.settings))
        run('./manage.py collectstatic --noinput')

    def update_db(self):
        run('./manage.py syncdb --settings=settings.{0} --noinput'.format(self.settings))
        run('./manage.py migrate --settings=settings.{0}'.format(self.settings))

    def restart_app(self):
        run('restart-app {0}'.format(env.apps[self.settings]))


deploy = DeployTask()