prefect-slack

library0.3.1pypiunverified

The `prefect-slack` library provides official integrations for connecting Prefect 2.x workflows with Slack. It enables sending notifications and messages to Slack channels using webhooks or bot tokens, typically via Prefect Blocks. The current stable version is `0.3.1`, and it's part of the PrefectHQ monorepo, with releases often following the Prefect core library's major versions, though `prefect-slack` `0.3.1` is specifically for Prefect `2.x`.

workflow communication devops

pip install prefect-slack

homepage ↗

INSTALL

IMPORT

SIG · PREFECT-SLACK

prefect-slack

workflowenv0.3.1

Install

23.6s avg

Import

—

Disk

257MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.3.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.910 runs

installs and imports cleanly · install 0.0s · import 0.000s · 259.6MB

glibc

py 3.10–3.910 runs

installs and imports cleanly · install 23.6s · import 0.000s · 262MB

257MB installed

● package 257MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

SlackWebhook

✓ from prefect_slack.webhooks import SlackWebhook

SlackMessage

✓ from prefect_slack.messages import SlackMessage

This quickstart demonstrates how to send a simple Slack notification from a Prefect flow using the `SlackWebhook` block. It requires a Slack incoming webhook URL, which should be set as an environment variable (`SLACK_WEBHOOK_URL`) for secure handling of credentials. In a production environment, it's recommended to create and save `SlackWebhook` blocks via the Prefect UI or API to reuse them across multiple flows and deployments.

import os from prefect import flow from prefect_slack.webhooks import SlackWebhook @flow(log_prints=True) def send_slack_notification_flow(message: str = "Hello from Prefect!"): """Sends a custom message to Slack via a configured webhook.""" # Retrieve Slack Webhook URL from environment variables or Prefect secrets slack_webhook_url = os.environ.get("SLACK_WEBHOOK_URL", "") if not slack_webhook_url: print("Warning: SLACK_WEBHOOK_URL environment variable is not set. Skipping Slack notification.") return # Initialize the SlackWebhook block with the URL # For production, consider creating and storing this block in the Prefect UI/API # and loading it via await SlackWebhook.load("my-slack-webhook-block") webhook_block = SlackWebhook(url=slack_webhook_url) # Send the notification webhook_block.notify(body=message) print(f"Successfully sent Slack notification: {message}") if __name__ == "__main__": # To run this example, set the SLACK_WEBHOOK_URL environment variable: # export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX" send_slack_notification_flow(message="This is a test notification from my Prefect flow!")

Debug

Known issues

breakingThe `prefect-slack` library `0.3.1` is designed for Prefect core `2.x` (specifically versions `>=2.10.0,<3.0.0`). Using it with Prefect core `3.x` (which is currently in development/nightly releases) may lead to incompatibility issues or unexpected behavior. Always ensure your `prefect` core library version is compatible with your `prefect-slack` version.

fix

Ensure your `prefect` core library version is within the compatible range (e.g., `pip install 'prefect>=2.10.0,<3.0.0'`) when using `prefect-slack==0.3.1`.

affects: prefect-slack < 1.0.0 with prefect >= 3.0.0

gotchaSlack integrations, particularly webhooks, require proper authentication. The `SlackWebhook` block needs a valid URL to post messages. Incorrectly configured URLs or missing environment variables/secrets will prevent notifications from being sent.

fix

Always provide the `url` argument to `SlackWebhook` or `SlackMessage` blocks, ideally loading it from environment variables (e.g., `os.environ.get("SLACK_WEBHOOK_URL")`) or a Prefect secret block. For production, create and save the `SlackWebhook` block in the Prefect UI/API and load it by name (`await SlackWebhook.load("your-block-name")`).

affects: All versions

gotchaWhen using `SlackWebhook` or `SlackMessage` blocks, ensure they are instantiated or loaded correctly within the Prefect flow context. If blocks are not saved in the Prefect backend, they must be instantiated directly in code, which might expose credentials if not handled carefully (e.g., via environment variables).

fix

For reusable blocks with sensitive credentials (like webhook URLs), create and save them in the Prefect UI/API. Then, within your flow, load them using `await BlockClass.load("block-name")`. If instantiating directly in code, ensure credentials are sourced securely (e.g., from environment variables or a dedicated secret management system).

affects: All versions

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'prefect_slack'

The `prefect-slack` library has not been installed in your Python environment.

fix

Run `pip install prefect-slack` to install the library.

pydantic_core._pydantic_core.ValidationError: 1 validation error for SlackWebhook url URL is not a valid URL [type=url_parsing, input_value='']

The `SlackWebhook` block was instantiated without a valid `url` or the provided URL was empty/invalid.

fix

Ensure the `url` parameter passed to `SlackWebhook(url=...)` is a complete and valid Slack incoming webhook URL. If using environment variables, verify the variable is set and accessible.

TypeError: notify() missing 1 required positional argument: 'body'

The `notify()` method of `SlackWebhook` or `SlackMessage` was called without providing the `body` argument, which is the message content.

fix

Always pass the message content as the `body` argument to the `notify()` method, e.g., `webhook_block.notify(body='Your message here')`.

Upgrade

Version history

0.3.1latest on PyPI · released Nov 15, 2024

Audit

Dependencies

prefectrequiredCore Prefect library is required to define and run flows and utilize integrations. Version `0.3.1` of `prefect-slack` is compatible with Prefect core versions `>=2.10.0,<3.0.0`.

Agent activity

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node

OpenAI (training)

Resources

homepagehttps://docs.prefect.io/integrations/prefect-slack ↗