Slack webhooks API served by FastAPI
Slackers is a FastAPI implementation to handle Slack interactions and events. It serves endpoints to receive slash commands, app actions, interactive components. It also listens for events sent to the Slack Events API Slack Events.
You can install Slackers with pip
$ pip install slackers
You must configure the slack signing secret. This will be used to
verify the incoming requests signature.
$ export SLACK_SIGNING_SECRET=your_slack_signing_secret
Slackers will listen for activity from the Events API on /events, for
interactive components on /actions and for slash commands on /commands.
When an interaction is received, it will emit an event. You can listen
for these events as shown in the following examples.
On receiving a request, Slackers will emit an event which you can handle yourself. Slackers will also respond to Slack with an (empty) http 200 response telling Slack all is well received.
As said, Slackers uses the excellent FastAPI to serve it's endpoints. Since you're here, I'm assuming you know what FastAPI is, but if you don't, you can learn all about how that works with this tutorial.
Slackers offers you a router which you can include in your own FastAPI.
from fastapi import FastAPI
from slackers.server import router
app = FastAPI()
app.include_router(router)
# Optionally you can use a prefix
app.include_router(router, prefix='/slack')Once your server is running, the events endpoint is setup at /events, or if you use
the prefix as shown above, on /slack/events.
When setting up Slack to send events, it will first send a challenge to verify your endpoint. Slackers detects when a challenge is sent. You can simply start our api and Slackers will meet the challenge automatically.
On receiving an event, Slackers will emit a python event, which you can act upon as shown below.
import logging
from slackers.hooks import events
log = logging.getLogger(__name__)
@events.on("app_mention")
def handle_mention(payload):
log.info("App was mentioned.")
log.debug(payload)Once your server is running, the actions endpoint is setup at /actions, or if you use
the prefix as shown above, on /slack/actions.
On receiving an action, Slackers will emit a python event, which you can listen for as shown below. You can listen for the action type, or more specifically for the action id or callback id linked to the action.
import logging
from slackers.hooks import actions
log = logging.getLogger(__name__)
# Listening for the action type.
@actions.on("block_actions")
def handle_action(payload):
log.info("Action started.")
log.debug(payload)
# Listen for an action by it's action_id
@actions.on("block_actions:your_action_id")
def handle_action_by_id(payload):
log.info("Action started.")
log.debug(payload)
# Listen for an action by it's callback_id
@actions.on("block_actions:your_callback_id")
def handle_action_by_callback_id(payload):
log.info(f"Action started.")
log.debug(payload)Interactive message actions do not have an action_id. They do have a name and a type.
To act upon interactive messages, you can listen for the action type, interactive_message
as wel as the combination of the interactive_message and name, type or both.
import logging
from slackers.hooks import actions
log = logging.getLogger(__name__)
# Listening for the action type.
@actions.on("interactive_message")
def handle_action(payload):
log.info("Action started.")
log.debug(payload)
# Listen for an action by it's name
@actions.on("interactive_message:action_name")
def handle_action_by_id(payload):
log.info("Action started.")
log.debug(payload)
# Listen for an action by it's type
@actions.on("interactive_message:action_type")
def handle_action_by_callback_id(payload):
log.info(f"Action started.")
log.debug(payload)
# Listen for an action by it's name and type
@actions.on("interactive_message:action_name:action_type")
def handle_action_by_callback_id(payload):
log.info(f"Action started.")
log.debug(payload)Slackers tries to be fast to respond to Slack. The events you are listening for with the
likes of @actions.on(...) are scheduled as an async task in a fire and forget fashion.
After scheduling these events, Slackers will by default return an empty 200 response which
might happen before the events are handled.
In some cases you might want to act on the payload and return a custom response to Slack.
For this, you can use the slackers responder decorator to define your custom handler
function. This function is then used as a callback instead of returning the default response.
You must ensure your custom handler returns a starlette.responses.Response or one of it's
subclasses. You must furthermore ensure that there is only one responder responding to your
Slack request.
Please note that the events are also emitted, so you could have both @actions.on("block_action:xyz")
and @responder("block_action:xyz"). Just keep in mind that the event emissions are async and are
not awaited. In other words, Slackers doesn't ensure that the response (whether your custom response
or the default) is returned before or after the events are emitted.
from starlette.responses import JSONResponse
from slackers.hooks import responder
@responder("block_actions:your_callback_id")
def custom_handler(payload):
# handle your payload
...
return JSONResponse(content={"custom": "Custom Response"})Once your server is running, the commands endpoint is setup at /commands, or if you use
the prefix as shown above, on /slack/commands. Slackers will emit an event with the name
of the command, so if your command is /engage, you can listen for the event engage
(without the slash)
On receiving a command, Slackers will emit a python event, which you can listen for as shown below.
import logging
from slackers.hooks import commands
log = logging.getLogger(__name__)
@commands.on("engage") # responds to "/engage"
def handle_command(payload):
log.info("Command received")
log.debug(payload)Since events are emitted using pyee's Async event emitter, it is possible to define your event handlers as async functions. Just keep in mind that errors are in this case emitted on the 'error' event.
import logging
from slackers.hooks import commands
log = logging.getLogger(__name__)
@commands.on('error')
def log_error(exc):
log.error(str(exc))
@commands.on("engage") # responds to "/engage"
async def handle_command(payload):
...