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Slack Incoming Webhooks

Create a Slack webhook, save it as a relay target, and test delivery.

2 min read

Use this guide to send endpoint traffic to Slack.

Purpose#

Use this guide to:

  • Create a Slack incoming webhook.
  • Save Slack as a relay target.
  • Attach the target to an endpoint destination.
  • Test delivery.

Before you start#

  • Make sure that you have permission in the Slack workspace to create an incoming webhook.
  • Select the Slack channel that receives the messages.
  • Make sure that you can access Relay targets and Endpoints.

Procedure#

1. Create webhook URL in Slack#

  1. In the Slack app settings, enable Incoming Webhooks.
  2. Create a webhook for the channel.
  3. Copy the URL. Use https://hooks.slack.com/services/... for Slack. GovSlack uses https://hooks.slack-gov.com/services/....

2. Add Slack relay target#

  1. Open Relay targets.
  2. Select Add target.
  3. Select Slack webhook.
  4. Paste the Slack URL into Slack webhook URL and save.

The URL must use the Slack incoming webhook format on hooks.slack.com or hooks.slack-gov.com.

3. Attach Slack target to endpoint#

  1. Open the endpoint create page or the endpoint edit page.
  2. In Outputs, select the Slack target.
  3. If the generated Slack text or the template body sections need Markdown, set Slack Markdown.
  4. Save the endpoint.

4. Send test delivery#

  1. On Relay targets, select Send test for the Slack target.
  2. Make sure that the message appears in the Slack channel.
  3. To see the test result, look for Test accepted (TEST_ACCEPTED) in Activity.

Expected result#

  • The Slack target is listed, and you can select it as an endpoint destination.
  • The test traffic and the live endpoint traffic go to the selected channel.
  • Without a custom message template, PayloadRelay sends the incoming payload as Slack text. With a custom message template, PayloadRelay sends Slack attachment blocks with a top-level text fallback.

Common issues and fixes#

  • URL rejected: make sure that the URL uses hooks.slack.com/services/... or hooks.slack-gov.com/services/....
  • No message in Slack: make sure that the target is attached to the endpoint, and that the webhook is active.
  • Formatting issues: change the Slack Markdown toggle for a generated message. Slack-native blocks or attachments in the incoming payload control their own formatting.
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