Fix bug when using preview 2 path

Signed-off-by: Caleb Schoepp <caleb.schoepp@fermyon.com>

Author: calebschoepp

crates/factor-observe/src/host.rs

@@ -25,11 +25,13 @@ impl wasi_otel::Host for InstanceState {
 
         // Before we ever create any new spans make sure we track the original host span ID
         if state.original_host_span_id.is_none() {
-            // TODO: Note this is also failing to get anything meaningful through tracing::Span::current()
-            let context = dbg!(tracing::Span::current().context());
-            let span = dbg!(context.span());
-            let span_context = dbg!(span.span_context());
-            state.original_host_span_id = dbg!(Some(span_context.span_id()));
+            state.original_host_span_id = Some(
+                tracing::Span::current()
+                    .context()
+                    .span()
+                    .span_context()
+                    .span_id(),
+            );
         }
 
         // // Get span's parent based on whether it's a new root and whether there are any active spans
@@ -105,12 +107,12 @@ impl wasi_otel::Host for InstanceState {
     }
 
     async fn current_span_context(&mut self) -> Result<wasi_otel::SpanContext> {
-        // TODO: The bug is that tracing::Span::current() is not returning anything
-        let context = dbg!(dbg!(tracing::Span::current()).context());
-        let span = context.span();
-        let span_context = span.span_context();
-        let out: SpanContext = span_context.clone().into();
-        Ok(out)
+        Ok(tracing::Span::current()
+            .context()
+            .span()
+            .span_context()
+            .clone()
+            .into())
     }
 }
 

crates/telemetry/src/lib.rs

@@ -48,6 +48,15 @@ pub use propagation::inject_trace_context;
 /// spin_telemetry::metrics::monotonic_counter!(spin.metric_name = 1, metric_attribute = "value");
 /// ```
 pub fn init(spin_version: String) -> anyhow::Result<ShutdownGuard> {
+    // This filter globally filters out spans produced by wasi_http so that they don't conflict with
+    // the behaviour of the wasi-otel factor.
+    let wasi_http_trace_filter = tracing_subscriber::filter::filter_fn(|metadata| {
+        if metadata.is_span() && metadata.name() == "wit-bindgen export" {
+            return false;
+        }
+        true
+    });
+
     // This layer will print all tracing library log messages to stderr.
     let fmt_layer = fmt::layer()
         .with_writer(std::io::stderr)
@@ -78,6 +87,7 @@ pub fn init(spin_version: String) -> anyhow::Result<ShutdownGuard> {
 
     // Build a registry subscriber with the layers we want to use.
     registry()
+        .with(wasi_http_trace_filter)
         .with(otel_tracing_layer)
         .with(otel_metrics_layer)
         .with(fmt_layer)