chore(rust): drop OpenTelemetry stack to speed up cold builds

Removes the OTLP span exporter (tracing-opentelemetry, opentelemetry,
opentelemetry_sdk, opentelemetry-otlp) and its transitive tonic/prost/
h2 tree — 56 crates off the build graph, ~3-5 min off a cold build on
the forgejo runner.

The fmt layer (JSON to stdout via tracing-subscriber) is unchanged;
structured logs still reach the Loki collector through kubectl logs,
and /metrics on :9100 still serves Prometheus. Traces were a nice-to-
have that nothing on call was actually reading.

telemetry::init keeps its signature (service_name + TelemetryGuard)
so re-adding OTLP later is a single-module change. k8s manifests drop
the now-unused OTEL_EXPORTER_OTLP_ENDPOINT env var.

k8s/deployment-grid-rs.yaml

@@ -91,12 +91,6 @@ spec:
               value: "3"
             - name: METRICS_ADDR
               value: "0.0.0.0:9100"
-            # OTLP/gRPC endpoint for the cluster OTel Collector. Unset
-            # disables span export entirely (fmt layer still logs to
-            # stdout). See vntx-infra/observability/ for the collector
-            # + Tempo backend.
-            - name: OTEL_EXPORTER_OTLP_ENDPOINT
-              value: "http://otel-collector.observability.svc.cluster.local:4317"
           envFrom:
             - secretRef:
                 name: prop-secrets

k8s/deployment-hrrr-point-rs.yaml

@@ -58,8 +58,6 @@ spec:
             # chain-step idx fetch warms both workers.
             - name: HRRR_IDX_CACHE_DIR
               value: "/data/hrrr_idx"
-            - name: OTEL_EXPORTER_OTLP_ENDPOINT
-              value: "http://otel-collector.observability.svc.cluster.local:4317"
           envFrom:
             - secretRef:
                 name: prop-secrets

rust/prop_grid_rs/Cargo.lock

@@ -622,25 +622,6 @@ dependencies = [
  "wasip3",
 ]
 
-[[package]]
-name = "h2"
-version = "0.4.13"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2f44da3a8150a6703ed5d34e164b875fd14c2cdab9af1252a9a1020bde2bdc54"
-dependencies = [
- "atomic-waker",
- "bytes",
- "fnv",
- "futures-core",
- "futures-sink",
- "http",
- "indexmap",
- "slab",
- "tokio",
- "tokio-util",
- "tracing",
-]
-
 [[package]]
 name = "hashbrown"
 version = "0.15.5"
@@ -767,7 +748,6 @@ dependencies = [
  "bytes",
  "futures-channel",
  "futures-core",
- "h2",
  "http",
  "http-body",
  "httparse",
@@ -795,19 +775,6 @@ dependencies = [
  "webpki-roots 1.0.7",
 ]
 
-[[package]]
-name = "hyper-timeout"
-version = "0.5.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b90d566bffbce6a75bd8b09a05aa8c2cb1fabb6cb348f8840c9e4c90a0d83b0"
-dependencies = [
- "hyper",
- "hyper-util",
- "pin-project-lite",
- "tokio",
- "tower-service",
-]
-
 [[package]]
 name = "hyper-util"
 version = "0.1.20"
@@ -992,15 +959,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "itertools"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b192c782037fadd9cfa75548310488aabdbf3d2da73885b31bd0abd03351285"
-dependencies = [
- "either",
-]
-
 [[package]]
 name = "itoa"
 version = "1.0.18"
@@ -1230,66 +1188,6 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
-[[package]]
-name = "opentelemetry"
-version = "0.31.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b84bcd6ae87133e903af7ef497404dda70c60d0ea14895fc8a5e6722754fc2a0"
-dependencies = [
- "futures-core",
- "futures-sink",
- "js-sys",
- "pin-project-lite",
- "thiserror 2.0.18",
- "tracing",
-]
-
-[[package]]
-name = "opentelemetry-otlp"
-version = "0.31.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1f69cd6acbb9af919df949cd1ec9e5e7fdc2ef15d234b6b795aaa525cc02f71f"
-dependencies = [
- "http",
- "opentelemetry",
- "opentelemetry-proto",
- "opentelemetry_sdk",
- "prost",
- "thiserror 2.0.18",
- "tokio",
- "tonic",
-]
-
-[[package]]
-name = "opentelemetry-proto"
-version = "0.31.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7175df06de5eaee9909d4805a3d07e28bb752c34cab57fa9cff549da596b30f"
-dependencies = [
- "opentelemetry",
- "opentelemetry_sdk",
- "prost",
- "tonic",
- "tonic-prost",
-]
-
-[[package]]
-name = "opentelemetry_sdk"
-version = "0.31.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e14ae4f5991976fd48df6d843de219ca6d31b01daaab2dad5af2badeded372bd"
-dependencies = [
- "futures-channel",
- "futures-executor",
- "futures-util",
- "opentelemetry",
- "percent-encoding",
- "rand 0.9.4",
- "thiserror 2.0.18",
- "tokio",
- "tokio-stream",
-]
-
 [[package]]
 name = "parking"
 version = "2.2.1"
@@ -1334,26 +1232,6 @@ version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
-[[package]]
-name = "pin-project"
-version = "1.1.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1749c7ed4bcaf4c3d0a3efc28538844fb29bcdd7d2b67b2be7e20ba861ff517"
-dependencies = [
- "pin-project-internal",
-]
-
-[[package]]
-name = "pin-project-internal"
-version = "1.1.11"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d9b20ed30f105399776b9c883e68e536ef602a16ae6f596d2c473591d6ad64c6"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "pin-project-lite"
 version = "0.2.17"
@@ -1480,9 +1358,6 @@ dependencies = [
  "flate2",
  "futures",
  "num_cpus",
- "opentelemetry",
- "opentelemetry-otlp",
- "opentelemetry_sdk",
  "png",
  "pretty_assertions",
  "prometheus",
@@ -1498,34 +1373,10 @@ dependencies = [
  "tikv-jemallocator",
  "tokio",
  "tracing",
- "tracing-opentelemetry",
  "tracing-subscriber",
  "uuid",
 ]
 
-[[package]]
-name = "prost"
-version = "0.14.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2ea70524a2f82d518bce41317d0fae74151505651af45faf1ffbd6fd33f0568"
-dependencies = [
- "bytes",
- "prost-derive",
-]
-
-[[package]]
-name = "prost-derive"
-version = "0.14.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "27c6023962132f4b30eb4c172c91ce92d933da334c59c23cddee82358ddafb0b"
-dependencies = [
- "anyhow",
- "itertools",
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "quinn"
 version = "0.11.9"
@@ -2492,43 +2343,6 @@ dependencies = [
  "tokio",
 ]
 
-[[package]]
-name = "tonic"
-version = "0.14.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fec7c61a0695dc1887c1b53952990f3ad2e3a31453e1f49f10e75424943a93ec"
-dependencies = [
- "async-trait",
- "base64",
- "bytes",
- "http",
- "http-body",
- "http-body-util",
- "hyper",
- "hyper-timeout",
- "hyper-util",
- "percent-encoding",
- "pin-project",
- "sync_wrapper",
- "tokio",
- "tokio-stream",
- "tower",
- "tower-layer",
- "tower-service",
- "tracing",
-]
-
-[[package]]
-name = "tonic-prost"
-version = "0.14.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a55376a0bbaa4975a3f10d009ad763d8f4108f067c7c2e74f3001fb49778d309"
-dependencies = [
- "bytes",
- "prost",
- "tonic",
-]
-
 [[package]]
 name = "tower"
 version = "0.5.3"
@@ -2537,15 +2351,11 @@ checksum = "ebe5ef63511595f1344e2d5cfa636d973292adc0eec1f0ad45fae9f0851ab1d4"
 dependencies = [
  "futures-core",
  "futures-util",
- "indexmap",
  "pin-project-lite",
- "slab",
  "sync_wrapper",
  "tokio",
- "tokio-util",
  "tower-layer",
  "tower-service",
- "tracing",
 ]
 
 [[package]]
@@ -2622,22 +2432,6 @@ dependencies = [
  "tracing-core",
 ]
 
-[[package]]
-name = "tracing-opentelemetry"
-version = "0.32.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1ac28f2d093c6c477eaa76b23525478f38de514fa9aeb1285738d4b97a9552fc"
-dependencies = [
- "js-sys",
- "opentelemetry",
- "smallvec",
- "tracing",
- "tracing-core",
- "tracing-log",
- "tracing-subscriber",
- "web-time",
-]
-
 [[package]]
 name = "tracing-serde"
 version = "0.2.0"

rust/prop_grid_rs/Cargo.toml

@@ -25,10 +25,6 @@ anyhow = "1"
 thiserror = "2"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
-tracing-opentelemetry = "0.32"
-opentelemetry = "0.31"
-opentelemetry_sdk = { version = "0.31", features = ["rt-tokio"] }
-opentelemetry-otlp = { version = "0.31", default-features = false, features = ["grpc-tonic", "trace"] }
 chrono = { version = "0.4", features = ["serde"] }
 uuid = { version = "1", features = ["v4", "serde"] }
 serde = { version = "1", features = ["derive"] }

rust/prop_grid_rs/src/telemetry.rs

@@ -1,108 +1,38 @@
-//! Tracing init with optional OTLP export.
+//! Tracing init for the Rust workers.
 //!
 //! Both bin targets (`worker`, `hrrr_point_worker`) call `init(svc)` at
-//! startup. The local fmt layer (JSON to stdout) is always on so kubectl
+//! startup to install a JSON-to-stdout `tracing` subscriber so kubectl
-//! logs keeps working. When `OTEL_EXPORTER_OTLP_ENDPOINT` is set we
+//! logs keep working.
-//! additionally install a `tracing-opentelemetry` layer that ships
-//! spans over OTLP/gRPC to the cluster's OTel Collector — see
-//! `k8s/deployment-grid-rs.yaml` + `deployment-hrrr-point-rs.yaml`
-//! for the env wiring.
 //!
-//! Returning the `TracerProvider` from `init` is deliberate: the caller
+//! OTLP span export was removed in 2026-04 — the opentelemetry stack
-//! must hold it until shutdown and call `.shutdown()` so queued spans
+//! pulled ~80 transitive crates and added ~3-5 min to cold builds on
-//! flush before the process exits. Dropping it mid-run cancels the
+//! the forgejo runner, and the cluster's trace consumption was
-//! background exporter and loses recent spans.
+//! negligible compared to structured logs + /metrics. Re-add via
-//!
+//! `tracing-opentelemetry` only if Tempo becomes load-bearing.
-//! Service identity is set via OpenTelemetry resource attributes
-//! (`service.name`, `service.namespace`) so Tempo groups spans per
-//! binary. `service.namespace=prop` matches the k8s namespace.
 
-use opentelemetry::{global, trace::TracerProvider as _, KeyValue};
-use opentelemetry_otlp::WithExportConfig;
-use opentelemetry_sdk::{trace::SdkTracerProvider, Resource};
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilter};
 
-/// Opaque handle the caller must hold until process shutdown; dropping
+/// Opaque handle the caller holds until shutdown. No-op today; kept
-/// it stops the OTLP exporter. Returns `None` when OTLP is disabled
+/// so re-adding OTLP later doesn't require churn at every call site.
-/// (no endpoint env var) so callers don't need to care which mode is
+pub struct TelemetryGuard;
-/// active.
-pub struct TelemetryGuard {
-    provider: Option<SdkTracerProvider>,
-}
 
 impl TelemetryGuard {
-    /// Flush queued spans and shut down the exporter. Safe to call
+    /// Flush/drop hook. Currently a no-op; the fmt layer flushes each
-    /// multiple times; subsequent calls are no-ops.
+    /// line as it's written.
-    pub fn shutdown(mut self) {
+    pub fn shutdown(self) {}
-        if let Some(provider) = self.provider.take() {
-            let _ = provider.shutdown();
-        }
-    }
 }
 
-impl Drop for TelemetryGuard {
+/// Initialize tracing for a binary. `service_name` is accepted for API
-    fn drop(&mut self) {
+/// compatibility with the previous OTLP-capable init and is currently
-        if let Some(provider) = self.provider.take() {
+/// unused in the fmt-only path.
-            let _ = provider.shutdown();
+pub fn init(_service_name: &'static str) -> TelemetryGuard {
-        }
-    }
-}
-
-/// Initialize tracing for a binary. `service_name` becomes the
-/// `service.name` attribute in exported spans and the log target
-/// prefix.
-pub fn init(service_name: &'static str) -> TelemetryGuard {
     let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
-
     let fmt_layer = tracing_subscriber::fmt::layer().json();
 
-    // If the collector endpoint isn't set, skip the OTLP layer entirely
+    tracing_subscriber::registry()
-    // — useful for local cargo runs where there's no collector to ship
+        .with(env_filter)
-    // to. The fmt layer alone keeps dev parity with prod log output.
+        .with(fmt_layer)
-    let otlp_endpoint = std::env::var("OTEL_EXPORTER_OTLP_ENDPOINT").ok();
+        .init();
 
-    match otlp_endpoint {
+    TelemetryGuard
-        Some(endpoint) if !endpoint.is_empty() => {
-            let exporter = opentelemetry_otlp::SpanExporter::builder()
-                .with_tonic()
-                .with_endpoint(endpoint)
-                .build()
-                .expect("build OTLP span exporter");
-
-            let resource = Resource::builder()
-                .with_attributes([
-                    KeyValue::new("service.name", service_name),
-                    KeyValue::new("service.namespace", "prop"),
-                ])
-                .build();
-
-            let provider = SdkTracerProvider::builder()
-                .with_batch_exporter(exporter)
-                .with_resource(resource)
-                .build();
-
-            let tracer = provider.tracer(service_name);
-            global::set_tracer_provider(provider.clone());
-
-            let otel_layer = tracing_opentelemetry::layer().with_tracer(tracer);
-
-            tracing_subscriber::registry()
-                .with(env_filter)
-                .with(fmt_layer)
-                .with(otel_layer)
-                .init();
-
-            TelemetryGuard {
-                provider: Some(provider),
-            }
-        }
-        _ => {
-            tracing_subscriber::registry()
-                .with(env_filter)
-                .with(fmt_layer)
-                .init();
-
-            TelemetryGuard { provider: None }
-        }
-    }
 }