LocalRateLimit

The LocalRateLimit filter controls the frequency at which packets received downstream are forwarded upstream by the proxy.
Rate limiting is done independently per source (IP, Port) combination.

Filter name

quilkin.filters.local_rate_limit.v1alpha1.LocalRateLimit

Configuration Examples

// Wrap this example within an async main function since the
// local_rate_limit filter spawns a task on initialization
#[tokio::main]
async fn main() {
  let yaml = "
version: v1alpha1
static:
  filters:
    - name: quilkin.filters.local_rate_limit.v1alpha1.LocalRateLimit
      config:
        max_packets: 1000
        period: 1
  endpoints:
    - address: 127.0.0.1:7001
";
  let config = quilkin::config::Config::from_reader(yaml.as_bytes()).unwrap();
assert_eq!(config.source.get_static_filters().unwrap().len(), 1);
  quilkin::Builder::from(std::sync::Arc::new(config)).validate().unwrap();
}

To configure a rate limiter, we specify the maximum rate at which the proxy is allowed to forward packets. In the example above, we configured the proxy to forward a maximum of 1000 packets per second).

Be aware that due to some optimizations in the current rate limiter implementation, the enforced maximum number of packets is not always exact. It is in theory possible that the rate limiter allows a few packets through, however in practice this would be a rare occurrence and the maximum number of such packets that is in the worse case N-1 where N is the number of threads used to process packets. For example, a configuration allowing 1000 packets per second could potentially allow 1004 packets during some time window if we have up to 4 threads.

Packets that that exceeds the maximum configured rate are dropped.

Configuration Options (Rust Doc)

---
$schema: "http://json-schema.org/draft-07/schema#"
title: Config
description: "Config represents a [self]'s configuration."
type: object
required:
  - max_packets
  - period
properties:
  max_packets:
    description: The maximum number of packets allowed to be forwarded by the rate limiter in a given duration.
    type: integer
    format: uint
    minimum: 0.0
  period:
    description: "The duration in seconds during which max_packets applies. If none is provided, it defaults to one second."
    type: integer
    format: uint32
    minimum: 0.0

Metrics

• quilkin_filter_LocalRateLimit_packets_dropped
  A counter over the total number of packets that have exceeded the configured maximum rate limit and have been dropped as a result.