Guest tracing improvements to use tracing crate

.github/workflows/CargoPublish.yml

@@ -85,13 +85,6 @@ jobs:
           CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_PUBLISH_TOKEN }}
         if: env.PUBLISH_HYPERLIGHT_COMMON != 'false'
 
-      - name: Publish hyperlight-guest-tracing-macro
-        continue-on-error: ${{ inputs.dry_run }}
-        run: cargo publish --manifest-path ./src/hyperlight_guest_tracing_macro/Cargo.toml ${{ inputs.dry_run && '--dry-run' || '' }}
-        env:
-          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_PUBLISH_TOKEN }}
-        if: env.PUBLISH_HYPERLIGHT_GUEST_TRACING_MACRO != 'false'
-
       - name: Publish hyperlight-guest-tracing
         continue-on-error: ${{ inputs.dry_run }}
         run: cargo publish --manifest-path ./src/hyperlight_guest_tracing/Cargo.toml ${{ inputs.dry_run && '--dry-run' || '' }}

.github/workflows/dep_rust.yml

@@ -137,7 +137,7 @@ jobs:
           cargo check -p hyperlight-host --features crashdump
           cargo check -p hyperlight-host --features print_debug
           cargo check -p hyperlight-host --features gdb
-          cargo check -p hyperlight-host --features trace_guest,unwind_guest,mem_profile
+          cargo check -p hyperlight-host --features trace_guest,mem_profile
 
           # without any features
           just test-compilation-no-default-features ${{ matrix.config }}

Cargo.toml

@@ -11,7 +11,6 @@ members = [
     "src/hyperlight_host",
     "src/hyperlight_guest_capi",
     "src/hyperlight_guest_tracing",
-    "src/hyperlight_guest_tracing_macro",
     "src/hyperlight_testing",
     "fuzz",
     "src/hyperlight_guest_bin",
@@ -42,7 +41,6 @@ hyperlight-guest = { path = "src/hyperlight_guest", version = "0.9.0", default-f
 hyperlight-guest-bin = { path = "src/hyperlight_guest_bin", version = "0.9.0", default-features = false }
 hyperlight-testing = { path = "src/hyperlight_testing", default-features = false }
 hyperlight-guest-tracing = { path = "src/hyperlight_guest_tracing", version = "0.9.0", default-features = false }
-hyperlight-guest-tracing-macro = { path = "src/hyperlight_guest_tracing_macro", version = "0.9.0", default-features = false }
 hyperlight-component-util = { path = "src/hyperlight_component_util", version = "0.9.0", default-features = false }
 hyperlight-component-macro = { path = "src/hyperlight_component_macro", version = "0.9.0", default-features = false }
 

Justfile

@@ -78,7 +78,7 @@ test-like-ci config=default-target hypervisor="kvm":
     cargo check -p hyperlight-host --features crashdump
     cargo check -p hyperlight-host --features print_debug
     cargo check -p hyperlight-host --features gdb
-    cargo check -p hyperlight-host --features trace_guest,unwind_guest,mem_profile
+    cargo check -p hyperlight-host --features trace_guest,mem_profile
 
     @# without any driver (should fail to compile)
     just test-compilation-no-default-features {{config}}
@@ -194,20 +194,10 @@ test-rust-crashdump target=default-target features="":
 test-rust-tracing target=default-target features="":
     # Run tests for the tracing guest and macro
     cargo test -p hyperlight-guest-tracing --profile={{ if target == "debug" { "dev" } else { target } }}
-    cargo test -p hyperlight-guest-tracing-macro --profile={{ if target == "debug" { "dev" } else { target } }}
 
-    # Prepare the tracing guest for testing
+    # Build the tracing guest to ensure it builds with the tracing feature
     just build-rust-guests {{ target }} trace_guest
     just move-rust-guests {{ target }}
-    # Run hello-world example with tracing enabled to get the trace output
-    TRACE_OUTPUT="$(cargo run --profile={{ if target == "debug" { "dev" } else { target } }} --example hello-world --features {{ if features =="" {"trace_guest"} else { "trace_guest," + features } }})" && \
-        TRACE_FILE="$(echo "$TRACE_OUTPUT" | grep -oE 'Creating trace file at: [^ ]+' | awk -F': ' '{print $2}')" && \
-        echo "$TRACE_OUTPUT" && \
-        if [ -z "$TRACE_FILE" ]; then \
-            echo "Error: Could not extract trace file path from output." >&2 ; \
-            exit 1 ; \
-        fi && \
-        cargo run -p trace_dump ./{{ simpleguest_source }}/{{ target }}/simpleguest "$TRACE_FILE" list_frames
 
     # Rebuild the tracing guests without the tracing feature
     # This is to ensure that the tracing feature does not affect the other tests

docs/hyperlight-metrics-logs-and-traces.md

@@ -94,12 +94,11 @@ Once the container or the exe is running, the trace output can be viewed in the
 
 ## Guest Tracing, Unwinding, and Memory Profiling
 
-Hyperlight provides advanced observability features for guest code running inside micro virtual machines. You can enable guest-side tracing, stack unwinding, and memory profiling using the `trace_guest`, `unwind_guest`, and `mem_profile` features. This section explains how to build, run, and inspect guest traces.
+Hyperlight provides advanced observability features for guest code running inside micro virtual machines. You can enable guest-side tracing, stack unwinding, and memory profiling using the `trace_guest` and `mem_profile` features. This section explains how to build, run, and inspect guest traces.
 
 The following features are available for guest tracing:
 - `trace_guest`: Enables tracing for guest code, capturing function calls and execution time.
-- `unwind_guest`: Enables stack unwinding for guest code, allowing you to capture stack traces.
-- `mem_profile`: Enables memory profiling for guest code, capturing memory allocations and usage.
+- `mem_profile`: Enables memory profiling for guest code with stack unwinding, capturing memory allocations and usage.
 
 ### Building a Guest with Tracing Support
 
@@ -112,17 +111,29 @@ just move-rust-guests debug
 
 This will build the guest binaries with the `trace_guest` feature enabled and move them to the appropriate location for use by the host.
 
+**NOTE**: To enable the tracing in your application you need to use the `trace_guest` feature on the `hyperlight-guest-bin` and `hyperlight-guest` crates.
+
 ### Running a Hyperlight Example with Guest Tracing
 
 Once the guest is built, you can run a Hyperlight example with guest tracing enabled. For example:
 
 ```bash
-cargo run --example hello-world --features trace_guest
+RUST_LOG="info,hyperlight_host::sandbox=info,hyperlight_guest=trace,hyperlight_guest_bin=trace" cargo run --example tracing-otlp --features trace_guest
 ```
 
-This will execute the `hello-world` example, loading the guest with tracing enabled. During execution, trace data will be collected and written to a file in the `trace` directory.
+This will execute the `tracing-otlp` example, loading the guest with tracing enabled.
+During execution, trace data will be collected on the host and exported as opentelemetry spans/events.
+
+You can set up a collector to gather all the traces and inspect the traces from both host and guests.
+
+Due to the nature of execution inside a Sandbox, on a call basis, the guest tracing sets up a stack of spans to keep track of the correct parents for the incoming
+guest spans.
+We start with `call-to-guest` which contains all the spans coming from a guest. Additionally, for each exit into the host, we add another layer marking it with
+a `call-to-host` span to follow the execution in the host and correctly set it as a child of the active span in the guest.
+This logic simulates the propagation of Opentelemetry context that is usually done between two services, but cannot be done here seamlessly because the guest side
+runs `no_std` which `opentelemetry` doesn't know.
 
-### Inspecting Guest Trace Files
+### Inspecting Guest memory Trace Files (for mem_profile)
 
 To inspect the trace file generated by the guest, use the `trace_dump` crate. You will need the path to the guest symbols and the trace file. Run the following command:
 
@@ -140,7 +151,7 @@ This command will list the stack frames and tracing information captured during
 cargo run -p trace_dump ./src/tests/rust_guests/bin/debug/simpleguest ./trace/<UUID>.trace list_frames
 ```
 
-You can use additional features such as `unwind_guest` and `mem_profile` by enabling them during the build and run steps.
+You can use the `mem_profile` additional feature by enabling them during the build and run steps.
 
 > **Note:** Make sure to follow the build and run steps in order, and ensure that the guest binaries are up to date before running the host example.
 

src/hyperlight_common/Cargo.toml

@@ -26,7 +26,6 @@ spin = "0.10.0"
 default = ["tracing"]
 fuzzing = ["dep:arbitrary"]
 trace_guest = []
-unwind_guest = []
 mem_profile = []
 std = []
 

src/hyperlight_common/src/outb.rs

@@ -90,23 +90,20 @@ impl TryFrom<u8> for Exception {
 /// - CallFunction: makes a call to a host function,
 /// - Abort: aborts the execution of the guest,
 /// - DebugPrint: prints a message to the host
-/// - TraceRecordStack: records the stack trace of the guest
+/// - TraceBatch: reports a batch of spans and vents from the guest
 /// - TraceMemoryAlloc: records memory allocation events
 /// - TraceMemoryFree: records memory deallocation events
-/// - TraceRecord: records a trace event in the guest
 pub enum OutBAction {
     Log = 99,
     CallFunction = 101,
     Abort = 102,
     DebugPrint = 103,
-    #[cfg(feature = "unwind_guest")]
-    TraceRecordStack = 104,
+    #[cfg(feature = "trace_guest")]
+    TraceBatch = 104,
     #[cfg(feature = "mem_profile")]
     TraceMemoryAlloc = 105,
     #[cfg(feature = "mem_profile")]
     TraceMemoryFree = 106,
-    #[cfg(feature = "trace_guest")]
-    TraceRecord = 107,
 }
 
 impl TryFrom<u16> for OutBAction {
@@ -117,14 +114,12 @@ impl TryFrom<u16> for OutBAction {
             101 => Ok(OutBAction::CallFunction),
             102 => Ok(OutBAction::Abort),
             103 => Ok(OutBAction::DebugPrint),
-            #[cfg(feature = "unwind_guest")]
-            104 => Ok(OutBAction::TraceRecordStack),
+            #[cfg(feature = "trace_guest")]
+            104 => Ok(OutBAction::TraceBatch),
             #[cfg(feature = "mem_profile")]
             105 => Ok(OutBAction::TraceMemoryAlloc),
             #[cfg(feature = "mem_profile")]
             106 => Ok(OutBAction::TraceMemoryFree),
-            #[cfg(feature = "trace_guest")]
-            107 => Ok(OutBAction::TraceRecord),
             _ => Err(anyhow::anyhow!("Invalid OutBAction value: {}", val)),
         }
     }

src/hyperlight_guest/Cargo.toml

@@ -17,6 +17,7 @@ serde_json = { version = "1.0", default-features = false, features = ["alloc"] }
 hyperlight-common = { workspace = true }
 hyperlight-guest-tracing = { workspace = true, default-features = false }
 flatbuffers = { version= "25.2.10", default-features = false }
+tracing = { version = "0.1.41", default-features = false, features = ["attributes"] }
 
 [features]
 default = []