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Notifiers
Slack Notifications for Server Updates - Update-Watcher Slack Integration

Slack Notifications for Server Updates - Update-Watcher Slack Integration

Update-Watcher sends server update notifications to any Slack channel using incoming webhooks. Messages are formatted with Slack’s Block Kit for a clean, structured layout that groups updates by package manager and highlights security patches. Setup takes under two minutes and requires no bot permissions beyond posting messages.

Setup on Slack

Follow these steps to create an incoming webhook for your Slack workspace:

Step 1: Create a Slack App

Go to api.slack.com/apps and click Create New App.

Step 2: Select From Scratch

Select From scratch, give it a name (e.g., “Update Watcher”), and choose your workspace.

Step 3: Enable Incoming Webhooks

In the left sidebar, click Incoming Webhooks.

Step 4: Activate Webhooks

Toggle Activate Incoming Webhooks to On.

Step 5: Add Webhook to Workspace

Click Add New Webhook to Workspace at the bottom of the page.

Step 6: Select Channel

Select the channel where you want update notifications to appear and click Allow.

Step 7: Copy the Webhook URL

Copy the webhook URL. It looks like https://hooks.slack.com/services/T.../B.../....

Store the webhook URL in an environment variable rather than placing it directly in your configuration file.
Terminal
export UPDATE_WATCHER_SLACK_WEBHOOK="<your-slack-webhook-url>"

Configuration Options

OptionRequiredDefaultDescription
webhook_urlYes–Slack incoming webhook URL. Use an environment variable reference to keep it out of version control.
mention_on_securityNo–User or group to mention when security updates are detected. Examples: @channel, @here, <@U01234567> for a specific user, <!subteam^S01234567> for a user group.
use_emojiNotrueWhether to include emoji indicators in the notification. When enabled, package names and security labels are prefixed with contextual emoji.

Configuration Example

Add the Slack notifier to the notifiers section of your Update-Watcher configuration file:

config.yaml
notifiers:
  - type: slack
    webhook_url: ${UPDATE_WATCHER_SLACK_WEBHOOK}
    mention_on_security: "@channel"
    use_emoji: true

Minimal Configuration

If you only need basic notifications without mentions or emoji:

config.yaml
notifiers:
  - type: slack
    webhook_url: ${UPDATE_WATCHER_SLACK_WEBHOOK}

Message Format

Update-Watcher uses Slack’s Block Kit to produce structured messages. Each notification includes:

  • Header – The hostname of the server and a summary of available updates.
  • Checker sections – One section per enabled checker that found updates, listing each package with its current and available version.
  • Security highlights – Security updates are called out with a distinct label. When mention_on_security is set, the configured mention is included at the top of the message to trigger an alert.
  • Footer – Timestamp and Update-Watcher version.

The Block Kit formatting ensures messages render cleanly on desktop, mobile, and in Slack’s notification previews.

Security Mentions

The mention_on_security option is particularly useful for operations teams. When Update-Watcher detects security updates (for example, through APT’s security repository classification or DNF’s advisory metadata), the configured mention string is prepended to the message. This triggers Slack notifications for the mentioned users or groups, ensuring critical patches are not overlooked in busy channels.

Common values:

  • @channel – Notifies everyone in the channel.
  • @here – Notifies only active members.
  • <@U01234567> – Notifies a specific user (use their Slack member ID).
  • <!subteam^S01234567> – Notifies a specific user group.

Testing

After configuring the Slack notifier, run a test to verify delivery:

Terminal
update-watcher run

Check the configured Slack channel for the notification. If no updates are available on your system and your send_policy is set to the default only-on-updates, force a notification by temporarily setting send_policy: "always" in your configuration.

For troubleshooting, run with verbose output:

Terminal
update-watcher run --verbose

This prints detailed logs including the HTTP response from Slack’s webhook endpoint. A 200 OK response confirms successful delivery.

💡
Testing tip: If no updates are available on your system, temporarily set send_policy: "always" in your configuration to force a notification and verify the integration is working.

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