demonstrate using metrics

Signed-off-by: William Zhang <wtzhang23@gmail.com>

Author: wtzhang23

integration/envoy.yaml

@@ -1,3 +1,6 @@
+admin:
+  address:
+    socket_address: { address: 127.0.0.1, port_value: 9901 }
 static_resources:
   listeners:
     - address:
@@ -16,7 +19,8 @@ static_resources:
                       domains:
                         - "*"
                       routes:
-                        - match:
+                        - name: catch_all
+                          match:
                             prefix: "/"
                           route:
                             cluster: httpbin
@@ -36,7 +40,14 @@ static_resources:
                       dynamic_module_config:
                         name: rust_module
                       filter_name: passthrough
-                  - name: dynamic_modules/conditional_deply
+                  - name: dynamic_modules/metrics
+                    typed_config:
+                      # https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/dynamic_modules/v3/dynamic_modules.proto#envoy-v3-api-msg-extensions-dynamic-modules-v3-dynamicmoduleconfig
+                      "@type": type.googleapis.com/envoy.extensions.filters.http.dynamic_modules.v3.DynamicModuleFilter
+                      dynamic_module_config:
+                        name: rust_module
+                      filter_name: metrics
+                  - name: dynamic_modules/conditional_delay
                     typed_config:
                       # https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/dynamic_modules/v3/dynamic_modules.proto#envoy-v3-api-msg-extensions-dynamic-modules-v3-dynamicmoduleconfig
                       "@type": type.googleapis.com/envoy.extensions.filters.http.dynamic_modules.v3.DynamicModuleFilter

rust/src/http_metrics.rs

@@ -0,0 +1,119 @@
+use std::time::Instant;
+
+use envoy_proxy_dynamic_modules_rust_sdk::*;
+
+/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilterConfig`] trait.
+///
+/// The trait corresponds to a Envoy filter chain configuration.
+pub struct FilterConfig {
+    _filter_config: String,
+    route_latency: EnvoyHistogramVecId,
+}
+
+impl FilterConfig {
+    /// This is the constructor for the [`FilterConfig`].
+    ///
+    /// filter_config is the filter config from the Envoy config here:
+    /// https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/dynamic_modules/v3/dynamic_modules.proto#envoy-v3-api-msg-extensions-dynamic-modules-v3-dynamicmoduleconfig
+    pub fn new<EC: EnvoyHttpFilterConfig>(
+        filter_config: &str,
+        envoy_filter_config: &mut EC,
+    ) -> Self {
+        Self {
+            _filter_config: filter_config.to_string(),
+            route_latency: envoy_filter_config
+                .define_histogram_vec("route_latency_ms", &["route_name"])
+                .unwrap(),
+        }
+    }
+}
+
+impl<EHF: EnvoyHttpFilter> HttpFilterConfig<EHF> for FilterConfig {
+    /// This is called for each new HTTP filter.
+    fn new_http_filter(&mut self, _envoy: &mut EHF) -> Box<dyn HttpFilter<EHF>> {
+        Box::new(Filter {
+            start_time: None,
+            route_name: None,
+            route_latency: self.route_latency,
+        })
+    }
+}
+
+/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilter`] trait.
+///
+/// This is a metrics filter that records per-route metrics of the request.
+pub struct Filter {
+    start_time: Option<Instant>,
+    route_latency: EnvoyHistogramVecId,
+    route_name: Option<String>,
+}
+
+impl Filter {
+    fn record_latency<EHF: EnvoyHttpFilter>(&mut self, envoy_filter: &mut EHF) {
+        let Some(start_time) = self.start_time else {
+            return;
+        };
+        let Some(route_name) = self.route_name.take() else {
+            return;
+        };
+        envoy_filter
+            .record_histogram_value_vec(
+                self.route_latency,
+                &[&route_name],
+                start_time.elapsed().as_millis() as u64,
+            )
+            .unwrap();
+    }
+}
+
+/// This implements the [`envoy_proxy_dynamic_modules_rust_sdk::HttpFilter`] trait.
+impl<EHF: EnvoyHttpFilter> HttpFilter<EHF> for Filter {
+    fn on_request_headers(
+        &mut self,
+        envoy_filter: &mut EHF,
+        _end_of_stream: bool,
+    ) -> abi::envoy_dynamic_module_type_on_http_filter_request_headers_status {
+        self.start_time = Some(Instant::now());
+        self.route_name = Some(
+            String::from_utf8(
+                envoy_filter
+                    .get_attribute_string(abi::envoy_dynamic_module_type_attribute_id::XdsRouteName)
+                    .unwrap_or_default()
+                    .as_slice()
+                    .to_vec(),
+            )
+            .unwrap(),
+        );
+        abi::envoy_dynamic_module_type_on_http_filter_request_headers_status::Continue
+    }
+
+    fn on_response_headers(
+        &mut self,
+        envoy_filter: &mut EHF,
+        end_of_stream: bool,
+    ) -> abi::envoy_dynamic_module_type_on_http_filter_response_headers_status {
+        if end_of_stream {
+            self.record_latency(envoy_filter);
+        }
+        abi::envoy_dynamic_module_type_on_http_filter_response_headers_status::Continue
+    }
+
+    fn on_response_body(
+        &mut self,
+        envoy_filter: &mut EHF,
+        end_of_stream: bool,
+    ) -> abi::envoy_dynamic_module_type_on_http_filter_response_body_status {
+        if end_of_stream {
+            self.record_latency(envoy_filter);
+        }
+        abi::envoy_dynamic_module_type_on_http_filter_response_body_status::Continue
+    }
+
+    fn on_request_trailers(
+        &mut self,
+        envoy_filter: &mut EHF,
+    ) -> abi::envoy_dynamic_module_type_on_http_filter_request_trailers_status {
+        self.record_latency(envoy_filter);
+        abi::envoy_dynamic_module_type_on_http_filter_request_trailers_status::Continue
+    }
+}

rust/src/lib.rs

@@ -2,6 +2,7 @@ use envoy_proxy_dynamic_modules_rust_sdk::*;
 
 mod http_access_logger;
 mod http_header_mutation;
+mod http_metrics;
 mod http_passthrough;
 mod http_random_auth;
 mod http_zero_copy_regex_waf;
@@ -29,7 +30,7 @@ fn init() -> bool {
 ///
 /// Returns None if the filter name or config is determined to be invalid by each filter's `new` function.
 fn new_http_filter_config_fn<EC: EnvoyHttpFilterConfig, EHF: EnvoyHttpFilter>(
-    _envoy_filter_config: &mut EC,
+    envoy_filter_config: &mut EC,
     filter_name: &str,
     filter_config: &[u8],
 ) -> Option<Box<dyn HttpFilterConfig<EHF>>> {
@@ -43,6 +44,10 @@ fn new_http_filter_config_fn<EC: EnvoyHttpFilterConfig, EHF: EnvoyHttpFilter>(
             .map(|config| Box::new(config) as Box<dyn HttpFilterConfig<EHF>>),
         "header_mutation" => http_header_mutation::FilterConfig::new(filter_config)
             .map(|config| Box::new(config) as Box<dyn HttpFilterConfig<EHF>>),
+        "metrics" => Some(Box::new(http_metrics::FilterConfig::new(
+            filter_config,
+            envoy_filter_config,
+        ))),
         _ => panic!("Unknown filter name: {filter_name}"),
     }
 }