Turns out you can't create the gauges in the layer fn

apollo-router/Cargo.toml

@@ -220,8 +220,6 @@ sysinfo = { version = "0.35.0", features = [
     "windows",
 ], default-features = false }
 thiserror = "2.0.0"
-tikv-jemallocator = { version =  "0.6.0", optional = true }
-tikv-jemalloc-ctl = { version = "0.6.0", features = ["stats"], optional = true }
 tokio.workspace = true
 tokio-stream = { version = "0.1.15", features = ["sync", "net"] }
 tokio-util = { version = "0.7.11", features = ["net", "codec", "time"] }
@@ -292,6 +290,10 @@ hyperlocal = { version = "0.9.1", default-features = false, features = [
     "client",
 ] }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+tikv-jemallocator = { version =  "0.6.0", optional = true }
+tikv-jemalloc-ctl = { version = "0.6.0", features = ["stats"], optional = true }
+
 [dev-dependencies]
 axum = { version = "0.8.1", features = ["http2", "ws"] }
 axum-server = "0.7.1"

apollo-router/src/axum_factory/axum_http_server_factory.rs

@@ -502,16 +502,23 @@ where
         early_cancel: configuration.supergraph.early_cancel,
         experimental_log_on_broken_pipe: configuration.supergraph.experimental_log_on_broken_pipe,
     }));
+    let session_count_instrument = session_count_instrument();
+    #[cfg(all(
+        feature = "global-allocator",
+        not(feature = "dhat-heap"),
+        target_os = "linux"
+    ))]
+    let (_epoch_advance_loop, jemalloc_instrument) = jemalloc_metrics_instruments();
     // Tie the lifetime of the various instruments to the lifetime of the router
-    // by creating them in a no-op layer.
-    router = router.layer(layer_fn(|service| {
-        let _session_count_instrument = session_count_instrument();
+    // by referencing them in a no-op layer.
+    router = router.layer(layer_fn(move |service| {
+        let _session_count_instrument = &session_count_instrument;
         #[cfg(all(
             feature = "global-allocator",
             not(feature = "dhat-heap"),
             target_os = "linux"
         ))]
-        let (_epoch_advance_loop, _je_malloc_instrument) = jemalloc_metrics_instruments();
+        let _jemalloc_instrument = &jemalloc_instrument;
         service
     }));
 

apollo-router/src/axum_factory/metrics.rs

@@ -11,13 +11,13 @@ pub(crate) mod jemalloc {
 
     use crate::metrics::meter_provider;
 
-    fn start_epoch_advance_loop() -> tokio::task::JoinHandle<()> {
+    pub(crate) fn start_epoch_advance_loop() -> tokio::task::JoinHandle<()> {
         tokio::spawn(async move {
             loop {
-                tokio::time::sleep(Duration::from_millis(500)).await;
                 if let Err(e) = tikv_jemalloc_ctl::epoch::advance() {
                     tracing::warn!("Failed to advance jemalloc epoch: {}", e);
                 }
+                tokio::time::sleep(Duration::from_millis(500)).await;
             }
         })
     }