BLACKGATE

Usage: Define Command

Command represents an external operation. To define a command, you must inherit from blackgate.Command.

Example:

from blackgate import Command

class GetCurrentUser(Command):

    group_key = 'service.session'
    command_key = 'get_current_user'

    def __init__(self, cookie):
        self.cookie = cookie

    def run(self):
        resp = requests.get('http://session-service/session', headers={'Cookie': self.cookie}, timeout=1)
        return resp.json()['user_id']

    def fallback(self):
        return None

Usage: Synchronous Execution

You can contruct command with parameters and then execute it:

get_current_user = GetCurrentUser(cookie='session=78b29404-92c9-49db-b87b-531b5f9cfc56')
user_id = get_current_user.execute()

Usage: Asynchronous Execution

You can execute a Command asynchronously by using the queue() method, as in the following example:

@tornado.gen.coroutine
def some_function():
    get_current_user = GetCurrentUser(cookie='session=78b29404-92c9-49db-b87b-531b5f9cfc56')
    user_id = yield get_current_user.queue()
    print(user_id)

Usage: Fallback

Usage: Proxy

Configure Blackgate Component:

from blackgate import component
component.add('executor_pool', {'group_key': 'api.v1', 'max_workers': 10})
component.install()
app = tornado.web.Application([
  (r'/api/v1/(.*)', HTTPProxy, dict(command=APIV1Command)),
])
app.listen(8888)
tornado.ioloop.IOLoop.current().start()

Route User Request to Inner Service:

from blackgate import HTTPProxyCommand

class APIService(HTTPProxyCommand):

    group_key = 'api.v1'

    command_key = 'proxy_v1_traffic'

    def before_request(self):
        path = self.request['path'].replace('/api', '')
        self.request['url'] = 'http://intra.service.com' + path

    def fallback(self):
        return dict(
            status_code=500,
            reason='Internal Server Error',
            headers={},
            content=json.dumps({
                'code': 500,
                'message': 'internal server error',
                'error': {}
            })
        )

ThreadExecutorPool

Executor Pool is the place where you can run external network calls.

Each command defines its group_key. You must register an executor_pool for specific group_key:

from blackgate import component
component.add('executor_pool', {'group_key': 'service.session', 'max_workers', 10})
# ...
component.install()