Databricks Rest APIs CORS Issue

[Chaitanya07]

Hello Team,

We are currently integrating Databricks Rest APIs into our in-house application for managing access permissions. While testing with curl and Postman, we've successfully accessed certain APIs like listing cluster permission. However, we're encountering CORS permission-related errors.

We would like to confirm if there are any restrictions from Databricks side regarding these specific APIs. Although the APIs are available and functional in our testing environment, we're unable to utilize some of them seamlessly within our UI.

Your guidance on resolving this issue would be greatly appreciated.

[Kaniz]

Hi @Chaitanya07, Dealing with CORS (Cross-Origin Resource Sharing) issues can be a bit tricky, but I’ll provide some guidance to help you resolve this issue when integrating Databricks REST APIs into your in-house application.

1. Understanding CORS:

   • CORS is a security feature implemented by web browsers to prevent unauthorized cross-origin requests. When your frontend (UI) makes requests to a different domain (such as Databricks APIs), the browser enforces CORS policies.
   • These policies can block or allow requests based on the origin (domain) of the request.

2. Common Causes of CORS Errors:

   • CORS errors occur when the frontend (your UI) tries to access Databricks APIs from a different domain (origin) than the one where the APIs are hosted.
   • Here are some common reasons for CORS errors:
     • Missing CORS Headers: The Databricks APIs might not be configured to include the necessary CORS headers in their responses.
     • Incorrect Origin: Ensure that the origin (domain) from which your UI is making requests is correctly specified.
     • Preflight Requests: Some requests (such as those with custom headers or non-GET/POST methods) trigger a preflight request. The server must respond correctly to preflight requests.

3. Solutions and Best Practices:

   • Backend Mediation:
     • One common approach is to use your backend server (server-side code) as a mediator between the frontend and Databricks APIs.
     • Your frontend sends requests to your backend, and the backend forwards them to Databricks. This way, the backend acts as the same origin for both frontend and Databricks.
     • This approach allows you to handle CORS headers on your backend, ensuring that the frontend doesn’t directly make cross-origin requests to Databricks.
   • Azure Functions API (if in Azure environment):
     • Consider creating an Azure Functions API that acts as an intermediary.
     • Your frontend triggers the Azure Function, which then makes the request to Databricks.
     • Again, this ensures that the frontend communicates with the same origin (Azure Functions) for all requests.
   • Check CORS Headers:
     • Verify that the Databricks APIs include the necessary CORS headers in their responses.
     • Headers like Access-Control-Allow-Origin should be set to allow your frontend’s domain.
   • Preflight Requests:
     • If your frontend sends custom headers or non-GET/POST requests, ensure that Databricks handles preflight requests correctly.
     • The preflight request (HTTP OPTIONS) should return the appropriate CORS headers.
   • Whitelist Your Domain:
     • If Databricks allows configuration of CORS settings, whitelist your frontend’s domain (e.g., localhost:4200 during development).
     • This tells Databricks to accept requests from your UI.

4. Debugging Tips:

   • Print any error messages you receive in your frontend’s catch block. This can help identify specific issues.
   • Double-check the correctness of the REST API URL, token, and job ID you’re using.
   • Ensure that the owner field in the job metadata is correctly specified when setting permissions via ...¹.

If you encounter any specific errors, feel free to share more details, and I’ll be happy to assist further! 🚀