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Slack

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Overview of steps

  1. Set up webhooks for Slack
  2. Update Mage project settings
  3. Customize message templates with dynamic variables (Pro only)

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Configure alerts in the Mage Pro UI

After you create your Slack webhook, you can configure alerts in the Mage Pro UI instead of editing metadata.yaml directly:
  1. For project defaults, go to Settings > Account > Alerts.
  2. For one pipeline, open the pipeline and go to Alerts. Pipeline-level settings override the project-level alert config for that pipeline.
  3. Choose the alert outcomes, enable Slack, enter the webhook URL, and use Send test notification to send a test alert before saving.
You can still reference secrets with values such as {{ env_var('MAGE_SLACK_WEBHOOK_URL') }}.

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Set up webhooks for Slack

To send notifications to Slack, you need to configure an incoming webhook:

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Update Mage project settings

Once you’ve set up webhooks for Slack, you should have a webhook URL that Slack provides. Here is an example webhook (yours may vary):
Follow these steps to add that webhook URL to your project settings:
  1. Open the Mage tool in your browser (e.g. http://localhost:6789/).
  2. Open a pipeline and start editing it (e.g. http://localhost:6789/pipelines/example_pipeline/edit).
  3. In your left sidebar in the file browser, scroll all the way down and click on a file named metadata.yaml.
  4. In the metadata.yaml file, add a section with the following configuration or update the existing notification_config section:
    If you omit the alert_on section it will default to trigger_failure and trigger_passed_sla. Options:
    • trigger_failure: alert when a run of a trigger fails
    • trigger_success: alert when a run of a trigger succeeds
    • trigger_passed_sla: alert when a SLA is missed.
      • In this context, SLA (Service Level Agreement) is an expected amount of time for the pipeline to complete.
      • If the pipeline runs longer than the SLA, an alert will be sent.
  5. In the metadata.yaml file, add the following values:
    Change the webhook_url value to be the webhook URL you created from Slack.

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Customize message templates

You can customize message templates in notification_config. Here is an example config:
You can customize the message template for success, failure, passed_sla scenarios. For each message template, you can specify either summary or details.
  • If you specify the summary, the slack message will be your summary + the url of the pipeline run page
  • If you specify the details, the details will be used as your slack message directly
To interpolate variables in the message template, you can use {variable_name} syntax. Here are the supported variables:
  1. execution_time
  2. pipeline_run_url
  3. pipeline_schedule_id
  4. pipeline_schedule_name
  5. pipeline_schedule_description
  6. pipeline_uuid
  7. error
    • available only for the failure message template
  8. stacktrace
    • available only for the failure message template
Note: For pipeline_run_url, the default host is http://localhost:6789. You can specify MAGE_PUBLIC_HOST to be the host url you want to use in the notification messages.

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🚀 Pro Only: Interpolate Mage Variables in Message Templates

If you’re using Mage Pro, you can interpolate environment variables and other Mage variables directly in your Slack message templates using the familiar Jinja-like syntax:
In addition to the variables mentioned above (e.g. execution_time, pipeline_uuid, etc), you can also use the following in your message templates in Mage Pro:
  1. start_time
  2. end_time
  3. duration (in seconds)
  4. env (this gets the value stored in the ENV environment variable)
This makes your Slack notifications more dynamic and context-aware — ideal for multi-environment deployments and advanced workflows.

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What next?

Whenever a pipeline run is successfully completed or fails, a Slack message will appear in the channel you configured the webhook URL for. Here is an example of what that message could look like: