Slack Integration#

Assert posts an alert to a Slack channel when a monitor fails, and again when it recovers. Follow-up updates thread under the first message.

The message names the assertion that failed, the expected value, the value your API returned, the regions that agreed, and the time. A failure re-runs across regions first, so one flaky check does not post an alert. Assert posts one alert per incident and closes the incident when the assertion passes again.

Routing is per monitor, so production and staging can land in different channels. Slack is on every paid plan.

Setup Guide#

Step 1: Add a Slack Channel#

1. Go to Alerts → Channels in your Assert dashboard
2. Click Add Channel
3. Select Slack from the list

Step 2: Authorize Assert#

1. Click Connect to Slack
2. Select your workspace
3. Select the channel that receives the alerts
4. Approve the permissions that Assert requests

Step 3: Configure Your Channel#

Set the channel, the events, and the fields to include:

Channel: #api-alerts
Alert on: Failures, Recoveries
Include: Response time, Error message, Region

Step 4: Assign to Monitors#

Open a monitor. Add the Slack channel under Alert Channels. A monitor can have more than one channel.

Alert Format#

A failure looks like this:

🔴 Monitor Failed: Production API
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Status: 500 Internal Server Error
Response Time: 2,340ms
Region: US East
Checked: 2 minutes ago

Assertion Failed:
$.status expected "success", got "error"

[View Details] [Acknowledge]

Best Practices#

Do not send every alert to your main channel. Create dedicated channels:

• #api-alerts for all API failures
• #api-critical for production, high priority
• #api-logs for verbose debugging output

Then route each monitor type to its own channel:

Turn on recovery notifications. Your team then sees when a monitor passes again.

Troubleshooting#

Not receiving alerts?

• Check that Assert is still authorized in your Slack workspace
• Check that the channel exists and Assert is a member
• Check that the monitor has the Slack channel assigned

Too many alerts?

• Increase the check interval to reduce noise
• Use alert cooldowns to stop duplicate notifications
• Split the alerts across channels by severity

Next Steps#

• Set up PagerDuty for on-call escalation
• Configure webhooks for custom integrations
• Learn about alerting best practices