docs: add observability samples

guide/samples/Cargo.toml

@@ -49,7 +49,12 @@ google-cloud-wkt.workspace    = true
 storage-samples.workspace     = true
 serde_json.workspace          = true
 tokio                         = { workspace = true, features = ["full", "macros"] }
-tracing-subscriber            = { workspace = true, default-features = true }
+tracing-subscriber            = { workspace = true, features = ["json"] }
+opentelemetry                 = { workspace = true }
+opentelemetry-otlp            = { workspace = true, features = ["grpc-tonic", "trace"] }
+opentelemetry_sdk             = { workspace = true, features = ["rt-tokio"] }
+tracing-opentelemetry         = { workspace = true }
+tracing                       = { workspace = true }
 # Formatting trick: this comment preserves formatting in the preceding block.
 google-cloud-compute-v1 = { workspace = true, default-features = false, features = [
   "default-rustls-provider",

guide/samples/src/lib.rs

@@ -23,6 +23,7 @@ pub mod error_handling;
 pub mod examine_error_details;
 pub mod gemini;
 pub mod logging;
+pub mod observability;
 pub mod pagination;
 pub mod retry_policies;
 pub mod update_resource;

guide/samples/src/observability/logging.rs

@@ -0,0 +1,37 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// [START rust_observability_logging] ANCHOR: rust_observability_logging
+use google_cloud_secretmanager_v1::client::SecretManagerService;
+use tracing_subscriber::layer::SubscriberExt;
+use tracing_subscriber::util::SubscriberInitExt;
+
+pub async fn sample() -> anyhow::Result<()> {
+    // Output `WARN` logs for failed logical client requests, and `DEBUG` logs
+    // for failed low-level RPC attempts from the client library crate.
+    let filter = tracing_subscriber::EnvFilter::new("warn,google_cloud_secretmanager=debug");
+
+    tracing_subscriber::registry()
+        .with(filter)
+        .with(tracing_subscriber::fmt::layer().json())
+        .init();
+
+    let _client = SecretManagerService::builder()
+        .with_tracing()
+        .build()
+        .await?;
+
+    Ok(())
+}
+// [END rust_observability_logging] ANCHOR_END: rust_observability_logging

guide/samples/src/observability/mod.rs

@@ -0,0 +1,16 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub mod logging;
+pub mod tracing;

guide/samples/src/observability/tracing.rs

@@ -0,0 +1,44 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// [START rust_observability_tracing] ANCHOR: rust_observability_tracing
+use google_cloud_secretmanager_v1::client::SecretManagerService;
+use tracing_subscriber::Registry;
+use tracing_subscriber::layer::SubscriberExt;
+
+pub async fn sample() -> anyhow::Result<()> {
+    use opentelemetry::trace::TracerProvider as _;
+    let exporter = opentelemetry_otlp::SpanExporter::builder()
+        .with_tonic()
+        .build()?;
+    let provider = opentelemetry_sdk::trace::SdkTracerProvider::builder()
+        .with_batch_exporter(exporter)
+        .build();
+    let tracer = provider.tracer("example");
+
+    // Create a tracing layer that sends data to an OpenTelemetry Collector running on localhost.
+    let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);
+
+    // Register the subscriber globally
+    let subscriber = Registry::default().with(telemetry);
+    tracing::subscriber::set_global_default(subscriber)?;
+
+    let _client = SecretManagerService::builder()
+        .with_tracing()
+        .build()
+        .await?;
+
+    Ok(())
+}
+// [END rust_observability_tracing] ANCHOR_END: rust_observability_tracing