containers: Add SpanContext to relevant container.capnp calls

src/workerd/api/container.c++

@@ -211,6 +211,9 @@ void Container::start(jsg::Lock& js, jsg::Optional<StartupOptions> maybeOptions)
   StartupOptions options = kj::mv(maybeOptions).orDefault({});
 
   auto req = rpcClient->startRequest();
+  KJ_IF_SOME(spanContext, IoContext::current().getCurrentTraceSpan().toSpanContext()) {
+    spanContext.toCapnp(req.initSpanContext());
+  }
   KJ_IF_SOME(entrypoint, options.entrypoint) {
     auto list = req.initEntrypoint(entrypoint.size());
     for (auto i: kj::indices(entrypoint)) {
@@ -462,6 +465,9 @@ jsg::Promise<jsg::Ref<ExecProcess>> Container::exec(
 
   auto params = req.initParams();
   params.setCombinedOutput(combinedOutput);
+  KJ_IF_SOME(spanContext, ioContext.getCurrentTraceSpan().toSpanContext()) {
+    spanContext.toCapnp(params.initSpanContext());
+  }
 
   // Some basic validation...
   KJ_IF_SOME(cwd, options.cwd) {
@@ -740,6 +746,9 @@ class Container::TcpPortWorkerInterface final: public WorkerInterface {
     // A lot of the following is copied from
     // capnp::HttpOverCapnpFactory::KjToCapnpHttpServiceAdapter::connect().
     auto req = port.connectRequest(capnp::MessageSize{4, 1});
+    KJ_IF_SOME(spanContext, IoContext::current().getCurrentTraceSpan().toSpanContext()) {
+      spanContext.toCapnp(req.initSpanContext());
+    }
     auto downPipe = kj::newOneWayPipe();
     req.setDown(byteStreamFactory.kjToCapnp(kj::mv(downPipe.out)));
     auto pipeline = req.send();

src/workerd/io/BUILD.bazel

@@ -401,6 +401,7 @@ wd_capnp_library(
     src = "container.capnp",
     deps = [
         ":compatibility-date_capnp",
+        ":worker-interface_capnp",
         "@capnp-cpp//src/capnp/compat:byte-stream_capnp",
     ],
 )

src/workerd/io/container.capnp

@@ -6,14 +6,15 @@ $Cxx.allowCancellation;
 
 using import "/capnp/compat/byte-stream.capnp".ByteStream;
 using CompatibilityFlags = import "/workerd/io/compatibility-date.capnp".CompatibilityFlags;
+using SpanContext = import "/workerd/io/worker-interface.capnp".SpanContext;
 
 interface Container @0x9aaceefc06523bca {
   # RPC interface to talk to a container, for containers attached to Durable Objects.
   #
   # When the actor shuts down, workerd will drop the `Container` capability, at which point
   # the container engine should implicitly destroy the container.
 
-  status @0 () -> (running :Bool);
+  status @0 (spanContext :SpanContext) -> (running :Bool);
   # Returns the container's current status. The runtime will always call this at DO startup.
 
   start @1 StartParams -> ();
@@ -53,6 +54,8 @@ interface Container @0x9aaceefc06523bca {
 
     containerSnapshotId @7 :Text;
     # Id of the full container snapshot to restore before the container starts.
+
+    spanContext @8 :SpanContext;
   }
 
   struct Label {
@@ -122,6 +125,8 @@ interface Container @0x9aaceefc06523bca {
 
     combinedOutput @3 :Bool;
     # If true, stderr is combined into stdout. If stdout is not set, combined output is discarded.
+
+    spanContext @4 :SpanContext;
   }
 
   struct Process {
@@ -168,7 +173,7 @@ interface Container @0x9aaceefc06523bca {
   interface Port {
     # Represents a port to which connections can be made.
 
-    connect @0 (down :ByteStream) -> (up :ByteStream);
+    connect @0 (down :ByteStream, spanContext :SpanContext) -> (up :ByteStream);
     # Forms a raw socket connection to the port.
     #
     # Note that when the Durable Object application uses the HTTP-oriented APIs, workerd will

src/workerd/io/worker.c++

@@ -3917,7 +3917,11 @@ kj::Promise<void> Worker::Actor::ensureConstructedImpl(IoContext& context, Actor
       //   with starting the script, and also if we could save the status across hibernations. But
       //   that would require some refactoring, and this RPC should (eventally) be local, so it's
       //   not a huge deal.
-      auto status = co_await c.statusRequest(capnp::MessageSize{4, 0}).send();
+      auto statusRequest = c.statusRequest(capnp::MessageSize{4, 0});
+      KJ_IF_SOME(spanContext, context.getCurrentTraceSpan().toSpanContext()) {
+        spanContext.toCapnp(statusRequest.initSpanContext());
+      }
+      auto status = co_await statusRequest.send();
       containerRunning = status.getRunning();
     }