Learn how to fix DigitalOcean Health Check errors. Our DigitalOcean Support team is here to help you with your questions and concerns.

How to Resolve DigitalOcean Health Check Errors

Health checks are an essential feature of the DigitalOcean App Platform. They help monitor the health and functionality of our applications or services, ensure they run as expected, and identify issues such as crashes or unresponsiveness.

When we deploy an app, the platform automatically performs health checks to verify that the application has started properly and is reachable. Failure to perform these checks can result in deployment errors. Today, we will explore the types of health checks and common errors and how to resolve them.

An Overview:

• Types of Health Checks
• Common Health Check Errors
• 1. Port Mismatch
• 2. Unresponsive Service
• 3. Incorrect Health Check Path
• 4. Application Crashes
• 5. Verify Networking and Permissions
• How to Diagnose and Fix Health Check Failures
• Key Parameters in Health Check Configuration

Types of Health Checks

DigitalOcean’s App Platform primarily uses two types of health checks:

1. HTTP Health Checks:

   The platform sends an HTTP request to a specific URL path in your app. It is considered healthy if your app responds with an HTTP status code in the 2xx range (e.g., 200 OK).
2. TCP Health Checks:

   The platform attempts to establish a TCP connection to a specified port. If the connection succeeds, the service is considered healthy.

We can customize these health checks based on our app’s architecture, such as defining a specific endpoint for the checks.

Common Health Check Errors

1. Port Mismatch

The app may not be listening on the expected port, or the port configured in the App Platform does not match the port used by our app.

Fix: Verify that the port our app listens on matches the port specified in the App Platform configuration. By default, DigitalOcean uses port 8080 for HTTP applications. If necessary, update the app’s configuration or code.

2. Unresponsive Service

The check will fail if the application starts but does not respond to health check requests within the expected timeframe.

Fix: Adjust the health check timeout settings or address potential app issues such as long loading times, memory leaks, or startup delays.

3. Incorrect Health Check Path

A specified health check endpoint (e.g., /health) does not exist or fails to return the expected response (e.g., HTTP 200 OK).

Fix: Ensure the endpoint is correctly defined and responds appropriately. Confirm that the URL path matches the App Platform settings if using a custom endpoint.

4. Application Crashes

The application crashes during startup or shuts down unexpectedly, causing the health check to fail.

Fix: Review application logs for errors, debug the app locally, and resolve any issues causing the crashes.

5. Verify Networking and Permissions

Limited memory, CPU, or disk I/O resources can prevent the app from starting or responding in time.

Fix: Scale the app by upgrading its plan or allocating more resources through the DigitalOcean control panel.

How to Diagnose and Fix Health Check Failures

1. First, review the application logs provided by the App Platform. Logs often reveal startup issues, response errors, or other problems impacting the app’s health.
2. Also, manually test the health check endpoint by navigating to it in a browser or using a command-line tool like `curl`:

   curl -I http:///health

   Verify that the endpoint returns an HTTP 200 status when healthy.
3. Run the app locally in a similar environment to ensure the health check endpoint functions as expected.
4. Then, adjust settings like initial delay, timeout, interval, and thresholds to accommodate the app’s startup and response times.
5. Ensure that the app has the necessary permissions to accept incoming requests and that the endpoint is accessible. Networking issues such as firewall settings can also block health checks.

Key Parameters in Health Check Configuration

When configuring health checks, consider these critical parameters:

• • Protocol: Choose between HTTP, HTTPS, or TCP.
  • Path: Define the URL endpoint for HTTP/HTTPS checks (e.g., /health).
  • Port: Specify the port your app listens on (default is 8080).
  • Initial Delay: Set the time to wait after the container starts before the first check.
  • Timeout: Define how long to wait for a response.
  • Interval: Specify the time between successive health checks.

• Thresholds: Set the number of failed checks required before marking the app unhealthy.

If a health check fails, the App Platform may attempt to restart the affected service automatically. Apps configured for auto-restart will attempt to recover from failures, but persistent issues could lead to repeated failures and deployment disruptions.

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Conclusion

Health checks are vital to maintaining robust and reliable applications on the DigitalOcean App Platform. By understanding how they work, identifying common errors, and following best practices for configuration, we can ensure your applications remain healthy and responsive.

In brief, our Support Experts demonstrated how to fix DigitalOcean Health Check errors.