This Slack integration is deprecated and will be removed in a future release. We recommend using the new [Slack App](./slack-app.md) integration instead.
The Slack integration allows Unleash to post Updates when a feature flag is updated. To set up Slack, you need to configure an incoming Slack webhook URL. You can follow [Sending messages using Incoming Webhooks](https://api.slack.com/incoming-webhooks) on how to do that. You can also choose to [create a slack app for Unleash](https://api.slack.com/apps), which will provide you with additional functionality to control how Unleash communicates messages on your Slack workspace.
The Slack integration will perform a single retry if the HTTP POST against the Slack Webhook URL fails (either a 50x or network error). Duplicate events may happen. You should never assume events always comes in order.
- **Slack Webhook URL** - This is the only required property. If you are using a Slack Application you must also make sure your application is allowed to post to the channel you want to post to.
- **Unleash URL** - The slack plugin uses the `server.unleashUrl` property to create the link back to Unleash in the posts. This can be set using the **UNLEASH_URL** environment variable or the `server.unleashUrl` property when starting the server from node.
The Slack integration also defined the Tag type "slack". You may use this tag to override which Slack channel Unleash should post updates to for this feature flag.
In the picture you can see we have defined two slack tags for the "new-payment-system" flag. In this example Unleash will post updates to the **#notifications** and **#random** channel.