Global middleware

Global middleware is run for all incoming requests, before any listener middleware. You can add any number of global middleware to your app by passing middleware functions to app.use(). Middleware functions are called with the same arguments as listeners, with an additional next() function.

Both global and listener middleware must call next() to pass control of the execution chain to the next middleware.

Refer to the module document to learn the available listener arguments.

Example

python

@app.use
def auth_acme(client, context, logger, payload, next):
    slack_user_id = payload["user"]
    help_channel_id = "C12345"

    try:
        # Look up user in external system using their Slack user ID
        user = acme.lookup_by_id(slack_user_id)
        # Add that to context
        context["user"] = user
    except Exception:
        client.chat_postEphemeral(
            channel=payload["channel"],
            user=slack_user_id,
            text=f"Sorry <@{slack_user_id}>, you aren't registered in Acme or there was an error with authentication. Please post in <#{help_channel_id}> for assistance"
        )

    # Pass control to the next middleware
    next()