runtime metric horrible idea

examples/Cargo.toml

@@ -14,7 +14,7 @@ default = ["rustls-tls", "kubederive", "ws", "latest", "socks5", "runtime", "ref
 kubederive = ["kube/derive"]
 openssl-tls = ["kube/client", "kube/openssl-tls", "kube/unstable-client"]
 rustls-tls = ["kube/client", "kube/rustls-tls", "kube/unstable-client"]
-runtime = ["kube/runtime", "kube/unstable-runtime"]
+runtime = ["kube/runtime", "kube/unstable-runtime", "kube/unstable-metrics"]
 socks5 = ["kube/socks5"]
 refresh = ["kube/oauth", "kube/oidc"]
 kubelet-debug = ["kube/kubelet-debug"]

examples/configmapgen_controller.rs

@@ -103,7 +103,19 @@ async fn main() -> Result<()> {
     });
 
     // limit the controller to running a maximum of two concurrent reconciliations
-    let config = Config::default().concurrency(2);
+    let metrics = Arc::new(kube::runtime::metrics::Metrics::default());
+    let config = Config::default()
+        .concurrency(2)
+        .metrics(metrics.clone())
+        .debounce(Duration::from_secs(3));
+    tokio::spawn(async move {
+        // Show metric state every 5 seconds
+        loop {
+            tokio::time::sleep(std::time::Duration::from_secs(5)).await;
+            let state = metrics.scheduler.read();
+            info!("Current metrics: {state:?}");
+        }
+    });
 
     Controller::new(cmgs, watcher::Config::default())
         .owns(cms, watcher::Config::default())

kube-runtime/Cargo.toml

@@ -17,6 +17,7 @@ unstable-runtime-subscribe = []
 unstable-runtime-predicates = []
 unstable-runtime-stream-control = []
 unstable-runtime-reconcile-on = []
+unstable-metrics = []
 
 [package.metadata.docs.rs]
 features = ["k8s-openapi/latest", "unstable-runtime"]

kube-runtime/src/controller/mod.rs

@@ -353,6 +353,11 @@ where
         channel::mpsc::channel::<ScheduleRequest<ReconcileRequest<K>>>(APPLIER_REQUEUE_BUF_SIZE);
     let error_policy = Arc::new(error_policy);
     let delay_store = store.clone();
+
+    #[cfg(feature = "unstable-metrics")]
+    let metrics = config.metrics.clone();
+
+    // TODO: how to share Metrics with debounced_scheduler?
     // Create a stream of ObjectRefs that need to be reconciled
     trystream_try_via(
         // input: stream combining scheduled tasks and user specified inputs event
@@ -378,6 +383,9 @@ where
         // all the Oks from the select gets passed through the scheduler stream, and are then executed
         move |s| {
             Runner::new(
+                #[cfg(feature = "unstable-metrics")]
+                debounced_scheduler(s, config.debounce).with_metrics(metrics.scheduler.clone()),
+                #[cfg(not(feature = "unstable-metrics"))]
                 debounced_scheduler(s, config.debounce),
                 config.concurrency,
                 move |request| {
@@ -515,6 +523,8 @@ where
 pub struct Config {
     debounce: Duration,
     concurrency: u16,
+    #[cfg(feature = "unstable-metrics")]
+    metrics: Arc<crate::metrics::Metrics>,
 }
 
 impl Config {
@@ -548,6 +558,13 @@ impl Config {
         self.concurrency = concurrency;
         self
     }
+
+    /// A loose idea of exposing metrics...
+    #[cfg(feature = "unstable-metrics")]
+    pub fn metrics(mut self, metrics: Arc<crate::metrics::Metrics>) -> Self {
+        self.metrics = metrics;
+        self
+    }
 }
 
 /// Controller for a Resource `K`

kube-runtime/src/lib.rs

@@ -22,6 +22,7 @@ pub mod controller;
 pub mod events;
 
 pub mod finalizer;
+#[cfg(feature = "unstable-metrics")] pub mod metrics;
 pub mod reflector;
 pub mod scheduler;
 pub mod utils;

kube-runtime/src/metrics.rs

@@ -0,0 +1,28 @@
+//! Optional metrics exposed by the runtime
+use parking_lot::RwLock;
+use std::sync::Arc;
+
+/// Metrics relating to the `Scheduler`
+#[derive(Default, Debug)]
+pub struct SchedulerMetrics {
+    /// Current size of the scheduler queue
+    pub queue_depth: usize,
+}
+
+/// All metrics
+#[derive(Default, Debug)]
+pub struct Metrics {
+    /// kube build info
+    pub build_info: String,
+    /// Metrics from the scheduler
+    pub scheduler: Arc<RwLock<SchedulerMetrics>>,
+}
+
+impl Metrics {
+    fn new() -> Self {
+        Self {
+            build_info: env!("CARGO_PKG_VERSION").to_string(),
+            ..Default::default()
+        }
+    }
+}

kube-runtime/src/scheduler.rs

@@ -1,12 +1,15 @@
 //! Delays and deduplicates [`Stream`](futures::stream::Stream) items
 
+#[cfg(feature = "unstable-metrics")] use crate::metrics::SchedulerMetrics;
 use futures::{stream::Fuse, Stream, StreamExt};
 use hashbrown::{hash_map::Entry, HashMap};
+use parking_lot::RwLock;
 use pin_project::pin_project;
 use std::{
     collections::HashSet,
     hash::Hash,
     pin::Pin,
+    sync::Arc,
     task::{Context, Poll},
     time::Duration,
 };
@@ -51,6 +54,8 @@ pub struct Scheduler<T, R> {
     /// for a request to be emitted, if the scheduler is "uninterrupted" for the configured
     /// debounce period. Its primary purpose to deduplicate requests that expire instantly.
     debounce: Duration,
+    #[cfg(feature = "unstable-metrics")]
+    metrics: Arc<RwLock<SchedulerMetrics>>,
 }
 
 impl<T, R: Stream> Scheduler<T, R> {
@@ -61,8 +66,16 @@ impl<T, R: Stream> Scheduler<T, R> {
             pending: HashSet::new(),
             requests: requests.fuse(),
             debounce,
+            #[cfg(feature = "unstable-metrics")]
+            metrics: Default::default(),
         }
     }
+
+    #[cfg(feature = "unstable-metrics")]
+    pub(crate) fn with_metrics(mut self, metrics: Arc<RwLock<SchedulerMetrics>>) -> Self {
+        self.metrics = metrics;
+        self
+    }
 }
 
 impl<'a, T: Hash + Eq + Clone, R> SchedulerProj<'a, T, R> {
@@ -74,6 +87,9 @@ impl<'a, T: Hash + Eq + Clone, R> SchedulerProj<'a, T, R> {
             // Message is already pending, so we can't even expedite it
             return;
         }
+        #[cfg(feature = "unstable-metrics")]
+        self.update_metrics();
+
         let next_time = request
             .run_at
             .checked_add(*self.debounce)
@@ -140,6 +156,12 @@ impl<'a, T: Hash + Eq + Clone, R> SchedulerProj<'a, T, R> {
             self.pending.insert(msg);
         }
     }
+
+    /// Update metrics when configured
+    #[cfg(feature = "unstable-metrics")]
+    pub(crate) fn update_metrics(&mut self) {
+        self.metrics.write().queue_depth = self.queue.len();
+    }
 }
 
 /// See [`Scheduler::hold`]
@@ -167,6 +189,8 @@ where
         }
 
         scheduler.pop_queue_message_into_pending(cx);
+        #[cfg(feature = "unstable-metrics")]
+        scheduler.update_metrics();
         Poll::Pending
     }
 }

kube/Cargo.toml

@@ -33,6 +33,7 @@ admission = ["kube-core/admission"]
 derive = ["kube-derive", "kube-core/schema"]
 runtime = ["kube-runtime"]
 unstable-runtime = ["kube-runtime/unstable-runtime"]
+unstable-metrics = ["kube-runtime/unstable-metrics"]
 unstable-client = ["kube-client/unstable-client"]
 socks5 = ["kube-client/socks5"]
 http-proxy = ["kube-client/http-proxy"]