Airflow Slack Alerts: Webhook and Bot Token Setups, Tested on Airflow 3

To get Airflow failure alerts in Slack, install the Slack provider (apache-airflow-providers-slack), add a Slack connection, and attach a notifier to the task's on_failure_callback: send_slack_webhook_notification for an incoming webhook, or send_slack_notification for a bot token. On 7 November 2026 we ran a DAG with both notifiers and both Slack operators on Airflow 3.4.0 (the official apache/airflow image, which already ships provider 9.11.1 and slack_sdk 3.46.0) and posted into a test workspace. This is the DAG, the connection setup, what arrived in Slack, and the two errors that leave you with no alert at all.

Webhook or bot token?

A webhook is the quickest start: our guide to creating a Slack webhook takes about a minute. A bot token lets one connection post to many channels; see Slack bot tokens for the scopes. Our bot had chat:write and chat:write.customize.

The connections

We set both connections as environment variables, which Airflow reads as JSON:

AIRFLOW_CONN_SLACK_WEBHOOK='{"conn_type": "slackwebhook", "password": "https://hooks.slack.com/services/T000/B000/XXXX"}'
AIRFLOW_CONN_SLACK_API='{"conn_type": "slack", "password": "xoxb-your-bot-token"}'

The connection IDs are the lower-case part after AIRFLOW_CONN_, here slack_webhook and slack_api. In the UI, the same thing is Admin > Connections, type Slack Incoming Webhook or Slack API, with the URL or token in the password field.

The DAG we ran

from datetime import datetime
from airflow.sdk import DAG, task
from airflow.providers.slack.notifications.slack import send_slack_notification
from airflow.providers.slack.notifications.slack_webhook import send_slack_webhook_notification
from airflow.providers.slack.operators.slack import SlackAPIPostOperator
from airflow.providers.slack.operators.slack_webhook import SlackWebhookOperator

webhook_alert = send_slack_webhook_notification(
    slack_webhook_conn_id="slack_webhook",
    text=":red_circle: Task failed: {{ ti.dag_id }}.{{ ti.task_id }} (try {{ ti.try_number }}) {{ ti.log_url }}",
)

bot_alert = send_slack_notification(
    slack_conn_id="slack_api",
    channel="#data-alerts",
    text=":red_circle: {{ ti.task_id }} failed in {{ ti.dag_id }}, run {{ run_id }}",
)

with DAG(
    dag_id="slack_alerts_demo",
    start_date=datetime(2026, 1, 1),
    schedule=None,
    catchup=False,
) as dag:

    @task(on_failure_callback=[webhook_alert])
    def load_orders():
        raise ValueError("orders.csv has 0 rows")

    @task(on_failure_callback=[bot_alert])
    def build_report():
        raise RuntimeError("report query timed out")

    announce = SlackWebhookOperator(
        task_id="announce_start",
        slack_webhook_conn_id="slack_webhook",
        message="Pipeline slack_alerts_demo started",
    )

    post_summary = SlackAPIPostOperator(
        task_id="post_summary",
        slack_conn_id="slack_api",
        channel="#data-alerts",
        text="Summary from SlackAPIPostOperator",
    )

    announce >> [load_orders(), build_report()]
    announce >> post_summary

airflow dags test slack_alerts_demo ran the whole DAG in 9.3 seconds. Both failing tasks failed as written, and four messages arrived in the channel:

Notice the two senders. Everything sent through the webhook shows under the Slack app that owns the webhook. Everything sent with the bot token shows as "Airflow" with the Airflow logo, because both SlackAPIPostOperator and send_slack_notification default to username="Airflow" and an Airflow icon_url in the provider's source. The Jinja fields ({{ ti.task_id }}, {{ run_id }}, {{ ti.log_url }}) were filled in before sending.

The log link pointed to http://localhost:8080/.... The task runner builds it from the [api] base_url setting, which falls back to http://localhost:8080/ in the provider code we read, so set AIRFLOW__API__BASE_URL to the address your team opens.

Mistake 1: a typo in the connection ID

We gave a notifier slack_webhook_conn_id="slack_webhok". The task failed, the callback ran, and the task log said:

[error] Failed to send notification (sync): The conn_id `slack_webhok` isn't defined
[error] Failed to run task callback  kind=on_failure_callback
airflow.sdk.exceptions.AirflowNotFoundException: The conn_id `slack_webhok` isn't defined

Nothing reached Slack, and nothing else in the run changed: the task was failed either way, so the broken alert only shows in that task's log. Test every alert path once on purpose, as we did with the raise tasks above, before you rely on it.

Mistake 2: the bot is not in the channel

With a bot token, the bot has to be a member of the channel. SlackAPIPostOperator posting to a channel the bot had not joined failed the task with:

slack_sdk.errors.SlackApiError: The request to the Slack API failed. (url: https://slack.com/api/chat.postMessage)
The server responded with: {'ok': False, 'error': 'not_in_channel'}

Invite the bot with /invite @your-app in the channel. A webhook has no such problem, since it is tied to its channel when you create it.

Task callbacks or DAG callbacks

Airflow also takes on_failure_callback on the DAG(...) itself, for one alert per failed run. We tested task-level callbacks only, because each alert then names the task that broke.

For alerts outside Airflow, the same webhook works from a monitor such as Uptime Kuma or a CI job like GitHub Actions.

FAQ

Is SlackWebhookOperator the same as the webhook notifier?

They post the same way, but the operator is a task that runs in the DAG's order, while the notifier runs only when its callback fires. Use the operator for "pipeline started" or summary messages, and the notifier for failures.

Do I need to install anything on the official Docker image?

No. apache/airflow:latest (3.4.0 on 7 November 2026) already had apache-airflow-providers-slack 9.11.1. On a pip install of Airflow, add apache-airflow-providers-slack.

Why does my alert show "Airflow" instead of my app name?

That is the bot-token path, which sends username="Airflow" unless you pass your own username and icon_url. Our app had the chat:write.customize scope, which Slack's docs require for a custom name. Webhook posts kept the app's name.