resolver_timeout
The `resolver_timeout` directive sets the time limit for resolving DNS queries when using the Proxy-Wasm feature in NGINX.
Description
The resolver_timeout directive is critical for specifying the maximum duration allowed for DNS resolution operations in NGINX's Proxy-Wasm module. When NGINX is configured to act as a proxy, the service may need to resolve domain names to IP addresses to route requests properly. By setting the resolver_timeout, administrators can control how long NGINX will wait for a response from the DNS server before timing out. This helps in ensuring that requests do not hang indefinitely due to unresponsive DNS servers, thereby improving overall responsiveness and reliability of the service.
The parameter for resolver_timeout is defined in seconds and determines the timeout period for any DNS resolution process. A well-configured timeout can help balance between usability and performance; setting it too high may delay error responses, while too low could lead to frequent timeouts in case of slight DNS delays. It's worth noting that this directive is essential in high-availability environments where DNS resolution issues can lead to service outages or delays.
In practice, the proper setting for resolver_timeout will depend on the runtime environment and performance requirements of the application. Monitoring DNS performance and adjusting the timeout accordingly is a recommended approach for maintaining optimal service operations.
Config Example
http {
resolver 8.8.8.8; # Google's public DNS resolver
resolver_timeout 5s; # set DNS resolver timeout to 5 seconds
server {
location / {
proxy_pass http://example.com;
}
}
}Setting the timeout too low can lead to frequent resolution failures if the DNS server is slow.
Ensure that resolver directive is also properly set; otherwise, resolver_timeout will have no effect.
Not all contexts in which Proxy-Wasm operates will utilize DNS resolution. Confirm necessity before setting.