The http.max_warning_header_size setting in Elasticsearch controls the maximum size of the HTTP warning header that Elasticsearch will generate in its responses. This setting helps manage the size of warning messages sent back to clients, preventing excessively large headers that could potentially cause issues with HTTP clients or proxies.
Description
- Default value: 8KB
- Possible values: Any positive integer followed by a size unit (e.g., b, kb, mb)
- Recommendation: Keep the default value unless you encounter specific issues related to warning header size
This setting limits the size of the warning header to prevent it from growing too large, which could lead to problems with HTTP clients or intermediary systems. The default value of 8KB is suitable for most use cases, but you may need to adjust it if you frequently encounter truncated warning messages or issues related to large warning headers.
Example
To change the http.max_warning_header_size setting using the cluster settings API:
PUT /_cluster/settings
{
"persistent": {
"http.max_warning_header_size": "16kb"
}
}
You might want to increase this value if you're receiving truncated warning messages or if your application requires more detailed warnings. However, be cautious about setting it too high, as very large headers can cause issues with some HTTP clients or proxies.
Common Issues or Misuses
- Setting the value too low may result in truncated warning messages, potentially hiding important information.
- Setting the value too high could lead to excessively large HTTP headers, which might cause issues with some HTTP clients or proxies.
Do's and Don'ts
- Do monitor your Elasticsearch logs for any warnings related to truncated warning headers.
- Do consider increasing the value if you frequently see truncated warnings.
- Don't set the value unnecessarily high, as it may impact performance or cause issues with HTTP clients.
- Don't ignore warning messages; they often contain important information about your cluster's health or operation.
Frequently Asked Questions
Q: How can I tell if I need to increase the http.max_warning_header_size?
A: Look for log messages indicating truncated warnings or client-side errors related to large HTTP headers. If you frequently encounter these issues, you may need to increase the size.
Q: Will increasing http.max_warning_header_size affect Elasticsearch performance?
A: A moderate increase should not significantly impact performance. However, extremely large values could potentially increase network overhead and memory usage for storing and processing larger headers.
Q: Can I set different http.max_warning_header_size values for different nodes in my cluster?
A: While it's technically possible, it's generally recommended to keep this setting consistent across all nodes to ensure uniform behavior and avoid potential issues.
Q: How does http.max_warning_header_size interact with other HTTP-related settings in Elasticsearch?
A: This setting specifically affects the size of the warning header. Other HTTP-related settings, such as http.max_header_size, control different aspects of HTTP communication and should be configured independently based on your needs.
Q: Is there a way to completely disable warning headers instead of adjusting their size?
A: Elasticsearch doesn't provide a direct way to disable warning headers entirely, as they serve an important purpose in communicating potential issues. Instead of disabling them, it's better to address the underlying causes of warnings or adjust the size if necessary.
