Add remote write for metric-explorer-prometheus

metrics-exporter-prometheus/Cargo.toml

@@ -17,11 +17,12 @@ categories = ["development-tools::debugging"]
 keywords = ["metrics", "telemetry", "prometheus"]
 
 [features]
-default = ["http-listener", "push-gateway"]
+default = ["http-listener", "push-gateway","remote-write"]
 async-runtime = ["tokio", "hyper-util/tokio"]
 http-listener = ["async-runtime", "ipnet", "tracing", "_hyper-server"]
 uds-listener = ["http-listener"]
 push-gateway = ["async-runtime", "tracing", "_hyper-client"]
+remote-write = ["_hyper-client","async-runtime","dep:prost","dep:snap","dep:prometheus-parse"]
 _hyper-server = ["http-body-util", "hyper/server", "hyper-util/server-auto"]
 _hyper-client = [
     "http-body-util",
@@ -48,7 +49,10 @@ metrics-util = { version = "^0.18", path = "../metrics-util", default-features =
     "registry",
     "summary",
 ] }
+prometheus-parse = {version = "0.2.5", optional = true}
+prost = {workspace = true, optional = true}
 quanta = { workspace = true }
+snap = { version = "1.1.1", optional = true}
 thiserror = { workspace = true }
 tokio = { workspace = true, optional = true }
 tracing = { workspace = true, optional = true }
@@ -63,6 +67,10 @@ tracing-subscriber = { workspace = true, features = ["fmt"] }
 name = "prometheus_push_gateway"
 required-features = ["push-gateway"]
 
+[[example]]
+name = "prometheus_remote_write"
+required-features = ["remote-write"]
+
 [[example]]
 name = "prometheus_server"
 required-features = ["http-listener"]

metrics-exporter-prometheus/examples/prometheus_remote_write.rs

@@ -0,0 +1,73 @@
+/// Make sure to run this example with `--features remote-write` to properly enable remote write support.
+#[allow(unused_imports)]
+use std::thread;
+use std::time::Duration;
+
+#[allow(unused_imports)]
+use metrics::{counter, gauge, histogram};
+use metrics::{describe_counter, describe_histogram};
+#[allow(unused_imports)]
+use metrics_exporter_prometheus::PrometheusBuilder;
+#[allow(unused_imports)]
+use metrics_util::MetricKindMask;
+
+use quanta::Clock;
+use rand::{thread_rng, Rng};
+
+fn main() {
+    tracing_subscriber::fmt::init();
+
+    PrometheusBuilder::new()
+        .with_remote_write(
+            "http://127.0.0.1:9091/metrics/job/example",
+            Duration::from_secs(10),
+            "test-agent",
+        )
+        .expect("remote write endpoint should be valid")
+        .idle_timeout(
+            MetricKindMask::COUNTER | MetricKindMask::HISTOGRAM,
+            Some(Duration::from_secs(10)),
+        )
+        .install()
+        .expect("failed to install Prometheus recorder");
+
+    // We register these metrics, which gives us a chance to specify a description for them.  The
+    // Prometheus exporter records this description and adds it as HELP text when the endpoint is
+    // scraped.
+    //
+    // Registering metrics ahead of using them is not required, but is the only way to specify the
+    // description of a metric.
+    describe_counter!("tcp_server_loops", "The iterations of the TCP server event loop so far.");
+    describe_histogram!(
+        "tcp_server_loop_delta_secs",
+        "The time taken for iterations of the TCP server event loop."
+    );
+
+    let clock = Clock::new();
+    let mut last = None;
+
+    counter!("idle_metric").increment(1);
+    gauge!("testing").set(42.0);
+
+    // Loop over and over, pretending to do some work.
+    loop {
+        counter!("tcp_server_loops", "system" => "foo").increment(1);
+
+        if let Some(t) = last {
+            let delta: Duration = clock.now() - t;
+            histogram!("tcp_server_loop_delta_secs", "system" => "foo").record(delta);
+        }
+
+        let increment_gauge = thread_rng().gen_bool(0.75);
+        let gauge = gauge!("lucky_iterations");
+        if increment_gauge {
+            gauge.increment(1.0);
+        } else {
+            gauge.decrement(1.0);
+        }
+
+        last = Some(clock.now());
+
+        thread::sleep(Duration::from_millis(750));
+    }
+}

metrics-exporter-prometheus/src/common.rs

@@ -63,7 +63,9 @@ pub enum BuildError {
     /// The given push gateway endpoint is not a valid URI.
     #[error("push gateway endpoint is not valid: {0}")]
     InvalidPushGatewayEndpoint(String),
-
+    /// The given push gateway endpoint is not a valid URI.
+    #[error("remote write endpoint is not valid: {0}")]
+    InvalidRemoteWriteEndpoint(String),
     /// No exporter configuration was present.
     ///
     /// This generally only occurs when HTTP listener support is disabled, but no push gateway

metrics-exporter-prometheus/src/exporter/builder.rs

@@ -138,6 +138,37 @@ impl PrometheusBuilder {
         Ok(self)
     }
 
+    /// Configures the exporter to push periodic requests to endpoint by [remote write protocol](https://prometheus.io/docs/specs/remote_write_spec/).
+    ///
+    /// Running in remote write mode is mutually exclusive with the HTTP listener/push gateway i.e. enabling the remote write will
+    /// disable the HTTP listener/push gateway, and vise versa.
+    ///
+    /// Defaults to disabled.
+    ///
+    /// ## Errors
+    ///
+    /// If the given endpoint cannot be parsed into a valid URI, an error variant will be returned describing the error.
+    ///
+    #[cfg(feature = "remote-write")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "remote-write")))]
+    pub fn with_remote_write<T>(
+        mut self,
+        endpoint: T,
+        interval: Duration,
+        user_agent: &str,
+    ) -> Result<Self, BuildError>
+    where
+        T: AsRef<str>,
+    {
+        self.exporter_config = ExporterConfig::RemoteWrite {
+            endpoint: Uri::try_from(endpoint.as_ref())
+                .map_err(|e| BuildError::InvalidRemoteWriteEndpoint(e.to_string()))?,
+            interval,
+            user_agent: user_agent.to_string(),
+        };
+        Ok(self)
+    }
+
     /// Configures the exporter to expose an HTTP listener that functions as a [scrape endpoint], listening on a Unix
     /// Domain socket at the given path
     ///
@@ -486,6 +517,10 @@ impl PrometheusBuilder {
                         endpoint, interval, username, password, handle,
                     )
                 }
+                #[cfg(feature = "remote-write")]
+                ExporterConfig::RemoteWrite { endpoint, interval, user_agent } => {
+                    super::remote_write::new_remote_write(endpoint, interval, handle, &user_agent)
+                }
             },
         ))
     }

metrics-exporter-prometheus/src/exporter/mod.rs

@@ -48,6 +48,11 @@ enum ExporterConfig {
         password: Option<String>,
     },
 
+    // Run a remote write task sending to the given `endpoint` after `interval` time has elapsed,
+    // infinitely.
+    #[cfg(feature = "remote-write")]
+    RemoteWrite { endpoint: Uri, interval: Duration, user_agent: String },
+
     #[allow(dead_code)]
     Unconfigured,
 }
@@ -60,6 +65,8 @@ impl ExporterConfig {
             Self::HttpListener { .. } => "http-listener",
             #[cfg(feature = "push-gateway")]
             Self::PushGateway { .. } => "push-gateway",
+            #[cfg(feature = "remote-write")]
+            Self::RemoteWrite { .. } => "remote-write",
             Self::Unconfigured => "unconfigured,",
         }
     }
@@ -71,4 +78,9 @@ mod http_listener;
 #[cfg(feature = "push-gateway")]
 mod push_gateway;
 
+#[cfg(feature = "remote-write")]
+mod remote_write;
+#[cfg(feature = "remote-write")]
+mod remote_write_proto;
+
 pub(crate) mod builder;

metrics-exporter-prometheus/src/exporter/remote_write.rs

@@ -0,0 +1,75 @@
+use std::time::Duration;
+
+use http_body_util::{BodyExt, Collected, Full};
+use hyper::{body::Bytes, Uri};
+use hyper_util::{client::legacy::Client, rt::TokioExecutor};
+use tracing::error;
+
+use crate::PrometheusHandle;
+
+use super::{remote_write_proto::WriteRequest, ExporterFuture};
+
+// Creates an ExporterFuture implementing a remote write.
+pub(super) fn new_remote_write(
+    endpoint: Uri,
+    interval: Duration,
+    handle: PrometheusHandle,
+    user_agent: &str,
+) -> ExporterFuture {
+    let user_agent = user_agent.to_string();
+    Box::pin(async move {
+        let https = hyper_rustls::HttpsConnectorBuilder::new()
+            .with_native_roots()
+            .expect("no native root CA certificates found")
+            .https_or_http()
+            .enable_http1()
+            .build();
+        let client: Client<_, Full<Bytes>> = Client::builder(TokioExecutor::new())
+            .pool_idle_timeout(Duration::from_secs(30))
+            .build(https);
+
+        loop {
+            // Sleep for `interval` amount of time, and then do a push.
+            tokio::time::sleep(interval).await;
+
+            let output = handle.render();
+            let binary = match WriteRequest::from_text_format(output) {
+                Ok(req) => req,
+                Err(err) => {
+                    error!("failed to build output to remote write request: {}", err);
+                    continue;
+                }
+            };
+
+            let req = match binary.build_http_request(&endpoint, &user_agent) {
+                Ok(req) => req,
+                Err(err) => {
+                    error!("failed to build http remote write request {}", err);
+                    continue;
+                }
+            };
+            match client.request(req).await {
+                Ok(response) => {
+                    if !response.status().is_success() {
+                        let status = response.status();
+                        let status = status.canonical_reason().unwrap_or_else(|| status.as_str());
+                        let body = response
+                            .into_body()
+                            .collect()
+                            .await
+                            .map(Collected::to_bytes)
+                            .map_err(|_| ())
+                            .and_then(|b| String::from_utf8(b[..].to_vec()).map_err(|_| ()))
+                            .unwrap_or_else(|()| String::from("<failed to read response body>"));
+                        error!(
+                            message = "unexpected status after pushing metrics to remote write",
+                            status,
+                            %body,
+                        );
+                    }
+                }
+                Err(e) => error!("error sending request to remote write {}: {:?}", endpoint, e),
+            }
+        }
+    })
+}