The http.cors.enabled setting in Elasticsearch controls whether Cross-Origin Resource Sharing (CORS) is enabled for HTTP requests. When enabled, it allows web browsers to make requests to Elasticsearch from different domains, which is essential for web applications that need to interact with Elasticsearch directly from the client-side.
Description
- Default value:
false - Possible values:
trueorfalse - Recommendation: Enable only if necessary for your application architecture, and always in conjunction with proper security measures.
This setting is a boolean flag that determines whether Elasticsearch should respond to cross-origin requests. When set to true, Elasticsearch will include the appropriate CORS headers in its responses, allowing browsers to make requests from different origins.
Version Information
This setting has been available since early versions of Elasticsearch and continues to be supported in current versions.
Example
To enable CORS, you can use the cluster settings API:
PUT /_cluster/settings
{
"persistent": {
"http.cors.enabled": true,
"http.cors.allow-origin": "https://your-domain.com"
}
}
Reason for change: You might enable CORS when developing a web application that needs to make direct requests to Elasticsearch from the browser, such as a custom dashboard or search interface.
Effects: Enabling CORS allows specified origins to make requests to Elasticsearch, potentially increasing the attack surface if not properly secured.
Common Issues or Misuses
- Enabling CORS without proper origin restrictions, potentially exposing Elasticsearch to unauthorized access.
- Forgetting to set
http.cors.allow-originwhen enabling CORS, which is required for specifying allowed origins. - Misunderstanding that CORS is a security feature, when it's actually a browser security mechanism that needs to be complemented with proper authentication and authorization.
Do's and Don'ts
Do's:
- Enable CORS only if absolutely necessary for your application architecture.
- Always set
http.cors.allow-originto specific, trusted origins. - Use HTTPS for both your application and Elasticsearch when enabling CORS.
- Implement proper authentication and authorization mechanisms.
Don'ts:
- Don't set
http.cors.allow-originto "*" in production environments. - Don't enable CORS if your application architecture doesn't require it.
- Don't rely on CORS alone for security; it's not a substitute for proper access controls.
Frequently Asked Questions
Q: How does enabling CORS affect Elasticsearch security?
A: Enabling CORS doesn't directly impact Elasticsearch security, but it allows browsers to make cross-origin requests. This can increase the attack surface if not properly configured with specific allowed origins and complemented with strong authentication and authorization measures.
Q: Can I enable CORS for specific indices only?
A: No, the http.cors.enabled setting is cluster-wide. You cannot enable CORS for specific indices. If you need finer-grained control, consider using a reverse proxy.
Q: What should I set for http.cors.allow-origin in a development environment?
A: For development, you can set it to "*" to allow all origins. However, this is not recommended for production. In production, always specify the exact origins that should be allowed.
Q: Does enabling CORS affect performance?
A: The performance impact of enabling CORS is generally negligible. Elasticsearch simply needs to add a few extra headers to its responses when CORS is enabled.
Q: How can I test if CORS is correctly configured?
A: You can test CORS configuration by making a cross-origin request from a web page or using tools like cURL with the -H "Origin: http://example.com" flag to simulate a cross-origin request and check the response headers.
