Rust metrics

rust/Cargo.toml

@@ -19,7 +19,7 @@ members = ["examples/*"]
 [workspace.dependencies]
 anyhow = "1"
 opentelemetry = "0.30.0"
-opentelemetry_sdk = "0.30.0"
+opentelemetry_sdk = { version = "0.30.0", features = ["experimental_metrics_custom_reader"] }
 spin-sdk = "3.1.0"
 tracing = "0.1.41"
 tracing-opentelemetry = "0.31.0"

rust/README.md

@@ -7,10 +7,8 @@ Enables using OpenTelemetry within Rust WebAssembly components backed by [WASI O
 Build a version of [Spin](https://github.com/spinframework/spin) from this [branch](https://github.com/calebschoepp/spin/tree/wasi-otel) and then run the example of your choosing.
 
 ```sh
-git clone https://github.com/calebschoepp/spin
+git clone --branch wasi-otel --depth 1 https://github.com/calebschoepp/spin
 cd spin
-git fetch origin wasi-otel
-git checkout wasi-otel
 cargo install --path .
 spin plugin update
 spin plugin install otel
@@ -23,3 +21,18 @@ spin otel setup
 spin otel up
 curl localhost:3000
 ```
+
+## Notes about Tracing
+
+## Notes about Metrics
+
+We based the metrics portion of the Rust SDK on [`opentelemetry-prometheus`](https://github.com/open-telemetry/opentelemetry-rust/tree/c811cde1ae21c624870c1b952190e687b16f76b8/opentelemetry-prometheus).
+
+To summarize:
+- We initialize a [`ManualReader`](https://github.com/open-telemetry/opentelemetry-rust/blob/c811cde1ae21c624870c1b952190e687b16f76b8/opentelemetry-sdk/src/metrics/manual_reader.rs), and `Arc::clone` the reader into an _**Exporter**_ and a _**Collector**_.
+- We pass the _**Exporter**_ into an [`SdkMeterProvider`](https://github.com/open-telemetry/opentelemetry-rust/blob/c811cde1ae21c624870c1b952190e687b16f76b8/opentelemetry-sdk/src/metrics/meter_provider.rs), and when the various instruments associated with the provider are invoked, they will fill the `ManualReader` with metric data.
+- When we are ready to pass the metric information from the Wasm guest to the Wasm host, we will use the _**Collector**_ to retrieve a [`ResourceMetrics`](https://github.com/open-telemetry/opentelemetry-rust/blob/c811cde1ae21c624870c1b952190e687b16f76b8/opentelemetry-sdk/src/metrics/data/mod.rs#L13) struct from the `ManualReader` and pass it to the host.
+
+TODO: Add notes about the host implementation
+
+## Notes about Logs

rust/examples/spin-metrics/.gitignore

@@ -0,0 +1,2 @@
+target/
+.spin/

rust/examples/spin-metrics/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "spin-metrics"
+authors = ["Andrew Steurer <[email protected]>"]
+description = ""
+version = "0.1.0"
+rust-version = "1.78"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+anyhow = { workspace = true }
+opentelemetry = { workspace = true }
+opentelemetry_sdk = { workspace = true }
+opentelemetry-wasi = { path = "../../" }
+spin-sdk = { workspace = true }
+once_cell = "1.21.3"

rust/examples/spin-metrics/spin.toml

@@ -0,0 +1,18 @@
+spin_manifest_version = 2
+
+[application]
+name = "spin-metrics"
+version = "0.1.0"
+authors = ["Andrew Steurer <[email protected]>"]
+description = "A Spin application demonstrating the use of OpenTelemetry metrics"
+
+[[trigger.http]]
+route = "/..."
+component = "spin-metrics"
+
+[component.spin-metrics]
+source = "../../target/wasm32-wasip2/release/spin_metrics.wasm"
+allowed_outbound_hosts = []
+[component.spin-metrics.build]
+command = "cargo build --target wasm32-wasip2 --release"
+watch = ["src/**/*.rs", "Cargo.toml"]

rust/examples/spin-metrics/src/lib.rs

@@ -0,0 +1,107 @@
+use once_cell::sync::Lazy;
+use opentelemetry::{
+    global,
+    metrics::{Counter, Gauge, Histogram, UpDownCounter},
+    KeyValue,
+};
+use opentelemetry_sdk::{
+    metrics::{ManualReader, SdkMeterProvider},
+    Resource,
+};
+use opentelemetry_wasi::WasiMetricCollector;
+use spin_sdk::{
+    http::{IntoResponse, Request, Response},
+    http_component,
+};
+use std::sync::Arc;
+
+static READER: Lazy<Arc<ManualReader>> = Lazy::new(|| Arc::new(ManualReader::builder().build()));
+
+static _PROVIDER: Lazy<()> = Lazy::new(|| {
+    Lazy::force(&READER);
+    let exporter = opentelemetry_wasi::WasiMetricExporter::new(Arc::clone(&READER));
+    let provider = SdkMeterProvider::builder()
+        .with_reader(exporter)
+        .with_resource(
+            Resource::builder()
+                .with_service_name("spin-metrics")
+                .build(),
+        )
+        .build();
+
+    global::set_meter_provider(provider);
+});
+
+static COLLECTOR: Lazy<WasiMetricCollector> = Lazy::new(|| {
+    Lazy::force(&READER);
+    opentelemetry_wasi::WasiMetricCollector::new(Arc::clone(&READER))
+});
+
+static COUNTER: Lazy<Counter<u64>> = Lazy::new(|| {
+    Lazy::force(&_PROVIDER);
+    global::meter("spin_meter")
+        .u64_counter("spin_counter")
+        .build()
+});
+
+static UPDOWNCOUNTER: Lazy<UpDownCounter<i64>> = Lazy::new(|| {
+    Lazy::force(&_PROVIDER);
+    global::meter("spin_meter")
+        .i64_up_down_counter("spin_up_down_counter")
+        .build()
+});
+
+static HISTOGRAM: Lazy<Histogram<u64>> = Lazy::new(|| {
+    Lazy::force(&_PROVIDER);
+    global::meter("spin_meter")
+        .u64_histogram("spin_histogram")
+        .build()
+});
+
+static GAUGE: Lazy<Gauge<u64>> = Lazy::new(|| {
+    Lazy::force(&_PROVIDER);
+    global::meter("spin_meter").u64_gauge("spin_gauge").build()
+});
+
+#[http_component]
+fn handle_spin_metrics(_req: Request) -> anyhow::Result<impl IntoResponse> {
+    COUNTER.add(
+        10,
+        &[
+            KeyValue::new("counterkey1", "countervalue1"),
+            KeyValue::new("counterkey2", "countervalue2"),
+        ],
+    );
+
+    UPDOWNCOUNTER.add(
+        -1,
+        &[
+            KeyValue::new("updowncounterkey1", "updowncountervalue1"),
+            KeyValue::new("updowncounterkey2", "updowncountervalue2"),
+        ],
+    );
+
+    HISTOGRAM.record(
+        9,
+        &[
+            KeyValue::new("histogramkey1", "histogramvalue1"),
+            KeyValue::new("histogramkey2", "histogramvalue2"),
+        ],
+    );
+
+    GAUGE.record(
+        8,
+        &[
+            KeyValue::new("gaugekey1", "gaugevalue1"),
+            KeyValue::new("gaugekey2", "gaugevalue2"),
+        ],
+    );
+
+    COLLECTOR.collect()?;
+
+    Ok(Response::builder()
+        .status(200)
+        .header("content-type", "text/plain")
+        .body("Hello, World!")
+        .build())
+}

rust/src/lib.rs

@@ -1,6 +1,8 @@
+mod metrics;
 mod tracing;
 mod types;
 
+pub use metrics::*;
 pub use tracing::*;
 
 #[doc(hidden)]

rust/src/metrics.rs

@@ -0,0 +1,5 @@
+mod conversion;
+mod exporter;
+
+pub use exporter::WasiMetricCollector;
+pub use exporter::WasiMetricExporter;