Initial implementation of DO-attached containers API

src/workerd/api/actor-state.c++

@@ -825,10 +825,13 @@ kj::OneOf<jsg::Ref<DurableObjectId>, kj::StringPtr> ActorState::getId() {
   KJ_UNREACHABLE;
 }
 
-DurableObjectState::DurableObjectState(
-    Worker::Actor::Id actorId, kj::Maybe<jsg::Ref<DurableObjectStorage>> storage)
+DurableObjectState::DurableObjectState(Worker::Actor::Id actorId,
+    kj::Maybe<jsg::Ref<DurableObjectStorage>> storage,
+    kj::Maybe<rpc::Container::Client> container)
     : id(kj::mv(actorId)),
-      storage(kj::mv(storage)) {}
+      storage(kj::mv(storage)),
+      container(container.map(
+          [&](rpc::Container::Client& cap) { return jsg::alloc<Container>(kj::mv(cap)); })) {}
 
 void DurableObjectState::waitUntil(kj::Promise<void> promise) {
   IoContext::current().addWaitUntil(kj::mv(promise));

src/workerd/api/actor-state.h

@@ -8,6 +8,7 @@
 // See actor.h for APIs used by other Workers to talk to Actors.
 
 #include <workerd/api/actor.h>
+#include <workerd/api/container.h>
 #include <workerd/io/actor-cache.h>
 #include <workerd/io/actor-id.h>
 #include <workerd/io/compatibility-date.capnp.h>
@@ -462,7 +463,9 @@ class WebSocketRequestResponsePair: public jsg::Object {
 // The type passed as the first parameter to durable object class's constructor.
 class DurableObjectState: public jsg::Object {
  public:
-  DurableObjectState(Worker::Actor::Id actorId, kj::Maybe<jsg::Ref<DurableObjectStorage>> storage);
+  DurableObjectState(Worker::Actor::Id actorId,
+      kj::Maybe<jsg::Ref<DurableObjectStorage>> storage,
+      kj::Maybe<rpc::Container::Client> container);
 
   void waitUntil(kj::Promise<void> promise);
 
@@ -472,6 +475,10 @@ class DurableObjectState: public jsg::Object {
     return storage.map([&](jsg::Ref<DurableObjectStorage>& p) { return p.addRef(); });
   }
 
+  jsg::Optional<jsg::Ref<Container>> getContainer() {
+    return container.map([](jsg::Ref<Container>& c) { return c.addRef(); });
+  }
+
   jsg::Promise<jsg::JsRef<jsg::JsValue>> blockConcurrencyWhile(
       jsg::Lock& js, jsg::Function<jsg::Promise<jsg::JsRef<jsg::JsValue>>()> callback);
 
@@ -536,6 +543,7 @@ class DurableObjectState: public jsg::Object {
     JSG_METHOD(waitUntil);
     JSG_READONLY_INSTANCE_PROPERTY(id, getId);
     JSG_READONLY_INSTANCE_PROPERTY(storage, getStorage);
+    JSG_READONLY_INSTANCE_PROPERTY(container, getContainer);
     JSG_METHOD(blockConcurrencyWhile);
     JSG_METHOD(acceptWebSocket);
     JSG_METHOD(getWebSockets);
@@ -574,6 +582,7 @@ class DurableObjectState: public jsg::Object {
  private:
   Worker::Actor::Id id;
   kj::Maybe<jsg::Ref<DurableObjectStorage>> storage;
+  kj::Maybe<jsg::Ref<Container>> container;
 
   // Limits for Hibernatable WebSocket tags.
 

src/workerd/api/container.c++

@@ -0,0 +1,242 @@
+// Copyright (c) 2025 Cloudflare, Inc.
+// Licensed under the Apache 2.0 license found in the LICENSE file or at:
+//     https://opensource.org/licenses/Apache-2.0
+
+#include "container.h"
+
+#include <workerd/api/http.h>
+#include <workerd/io/io-context.h>
+
+namespace workerd::api {
+
+// =======================================================================================
+// Basic lifecycle methods
+
+Container::Container(rpc::Container::Client rpcClient)
+    : rpcClient(IoContext::current().addObject(kj::heap(kj::mv(rpcClient)))) {}
+
+void Container::start(jsg::Lock& js, jsg::Optional<StartupOptions> maybeOptions) {
+  JSG_REQUIRE(!running, Error, "start() cannot be called on a container that is already running.");
+
+  StartupOptions options = kj::mv(maybeOptions).orDefault({});
+
+  auto req = rpcClient->startRequest();
+  KJ_IF_SOME(entrypoint, options.entrypoint) {
+    auto list = req.initEntrypoint(entrypoint.size());
+    for (auto i: kj::indices(entrypoint)) {
+      list.set(i, entrypoint[i]);
+    }
+  }
+  req.setEnableInternet(options.enableInternet);
+
+  IoContext::current().addTask(req.send().ignoreResult());
+
+  running = true;
+}
+
+jsg::Promise<void> Container::monitor(jsg::Lock& js) {
+  JSG_REQUIRE(running, Error, "monitor() cannot be called on a container that is not running.");
+
+  return IoContext::current()
+      .awaitIo(js, rpcClient->monitorRequest(capnp::MessageSize{4, 0}).send().ignoreResult())
+      .then(js, [this](jsg::Lock& js) {
+    running = false;
+    KJ_IF_SOME(d, destroyReason) {
+      jsg::Value error = kj::mv(d);
+      destroyReason = kj::none;
+      js.throwException(kj::mv(error));
+    }
+  }, [this](jsg::Lock& js, jsg::Value&& error) {
+    running = false;
+    destroyReason = kj::none;
+    js.throwException(kj::mv(error));
+  });
+}
+
+jsg::Promise<void> Container::destroy(jsg::Lock& js, jsg::Optional<jsg::Value> error) {
+  if (!running) return js.resolvedPromise();
+
+  if (destroyReason == kj::none) {
+    destroyReason = kj::mv(error);
+  }
+
+  return IoContext::current().awaitIo(
+      js, rpcClient->destroyRequest(capnp::MessageSize{4, 0}).send().ignoreResult());
+}
+
+void Container::signal(jsg::Lock& js, int signo) {
+  JSG_REQUIRE(signo > 0 && signo <= 64, TypeError, "Invalid signal number.");
+  JSG_REQUIRE(running, Error, "signal() cannot be called on a container that is not running.");
+
+  auto req = rpcClient->signalRequest(capnp::MessageSize{4, 0});
+  req.setSigno(signo);
+  IoContext::current().addTask(req.send().ignoreResult());
+}
+
+// =======================================================================================
+// getTcpPort()
+
+// `getTcpPort()` returns a `Fetcher`, on which `fetch()` and `connect()` can be called. `Fetcher`
+// is a JavaScript wrapper around `WorkerInterface`, so we need to implement that.
+class Container::TcpPortWorkerInterface final: public WorkerInterface {
+ public:
+  TcpPortWorkerInterface(capnp::ByteStreamFactory& byteStreamFactory,
+      const kj::HttpHeaderTable& headerTable,
+      rpc::Container::Port::Client port)
+      : byteStreamFactory(byteStreamFactory),
+        headerTable(headerTable),
+        port(kj::mv(port)) {}
+
+  // Implements fetch(), i.e., HTTP requests. We form a TCP connection, then run HTTP over it
+  // (as opposed to, say, speaking http-over-capnp to the container service).
+  kj::Promise<void> request(kj::HttpMethod method,
+      kj::StringPtr url,
+      const kj::HttpHeaders& headers,
+      kj::AsyncInputStream& requestBody,
+      kj::HttpService::Response& response) override {
+    // URLs should have been validated earlier in the stack, so parsing the URL should succeed.
+    auto parsedUrl = KJ_REQUIRE_NONNULL(kj::Url::tryParse(url, kj::Url::Context::HTTP_PROXY_REQUEST,
+                                            {.percentDecode = false, .allowEmpty = true}),
+        "invalid url?", url);
+
+    // We don't support TLS.
+    JSG_REQUIRE(parsedUrl.scheme != "https", Error,
+        "Connencting to a container using HTTPS is not currently supported; use HTTP instead. "
+        "TLS is unnecessary anyway, as the connection is already secure by default.");
+
+    // Schemes other than http: and https: should have been rejected earlier, but let's verify.
+    KJ_REQUIRE(parsedUrl.scheme == "http");
+
+    // We need to convert the URL from proxy format (full URL in request line) to host format
+    // (path in request line, hostname in Host header).
+    auto newHeaders = headers.cloneShallow();
+    newHeaders.set(kj::HttpHeaderId::HOST, parsedUrl.host);
+    auto noHostUrl = parsedUrl.toString(kj::Url::Context::HTTP_REQUEST);
+
+    // Make a TCP connection...
+    auto pipe = kj::newTwoWayPipe();
+    auto connectionPromise =
+        connectImpl(*pipe.ends[1]).then([]() -> kj::Promise<void> { return kj::NEVER_DONE; });
+
+    // ... and then stack an HttpClient on it ...
+    auto client = kj::newHttpClient(headerTable, *pipe.ends[0]);
+
+    // ... and then adapt that to an HttpService ...
+    auto service = kj::newHttpService(*client);
+
+    // ... and now we can just forward our call to that.
+    co_await connectionPromise.exclusiveJoin(
+        service->request(method, noHostUrl, newHeaders, requestBody, response));
+  }
+
+  // Implements connect(), i.e., forms a raw socket.
+  kj::Promise<void> connect(kj::StringPtr host,
+      const kj::HttpHeaders& headers,
+      kj::AsyncIoStream& connection,
+      ConnectResponse& response,
+      kj::HttpConnectSettings settings) override {
+    JSG_REQUIRE(!settings.useTls, Error,
+        "Connencting to a container using TLS is not currently supported. It is unnecessary "
+        "anyway, as the connection is already secure by default.");
+
+    auto promise = connectImpl(connection);
+
+    kj::HttpHeaders responseHeaders(headerTable);
+    response.accept(200, "OK", responseHeaders);
+
+    return promise;
+  }
+
+  // The only `CustomEvent` that can happen through `Fetcher` is a JSRPC call. Maybe we will
+  // support this someday? But not today.
+  kj::Promise<CustomEvent::Result> customEvent(kj::Own<CustomEvent> event) override {
+    return event->notSupported();
+  }
+
+  // There's no way to invoke the remaining event types via `Fetcher`.
+  kj::Promise<void> prewarm(kj::StringPtr url) override {
+    KJ_UNREACHABLE;
+  }
+  kj::Promise<ScheduledResult> runScheduled(kj::Date scheduledTime, kj::StringPtr cron) override {
+    KJ_UNREACHABLE;
+  }
+  kj::Promise<AlarmResult> runAlarm(kj::Date scheduledTime, uint32_t retryCount) override {
+    KJ_UNREACHABLE;
+  }
+
+ private:
+  capnp::ByteStreamFactory& byteStreamFactory;
+  const kj::HttpHeaderTable& headerTable;
+  rpc::Container::Port::Client port;
+
+  // Connect to the port and pump bytes to/from `connection`. Used by both request() and
+  // connect().
+  kj::Promise<void> connectImpl(kj::AsyncIoStream& connection) {
+    // A lot of the following is copied from
+    // capnp::HttpOverCapnpFactory::KjToCapnpHttpServiceAdapter::connect().
+    auto req = port.connectRequest(capnp::MessageSize{4, 1});
+    auto downPipe = kj::newOneWayPipe();
+    req.setDown(byteStreamFactory.kjToCapnp(kj::mv(downPipe.out)));
+    auto pipeline = req.send();
+
+    // Make sure the request message isn't pinned into memory through the co_await below.
+    { auto drop = kj::mv(req); }
+
+    auto downPumpTask =
+        downPipe.in->pumpTo(connection)
+            .then([&connection, down = kj::mv(downPipe.in)](uint64_t) -> kj::Promise<void> {
+      connection.shutdownWrite();
+      return kj::NEVER_DONE;
+    });
+    auto up = pipeline.getUp();
+
+    auto upStream = byteStreamFactory.capnpToKjExplicitEnd(up);
+    auto upPumpTask = connection.pumpTo(*upStream)
+                          .then([&upStream = *upStream](uint64_t) mutable {
+      return upStream.end();
+    }).then([up = kj::mv(up), upStream = kj::mv(upStream)]() mutable -> kj::Promise<void> {
+      return kj::NEVER_DONE;
+    });
+
+    co_await pipeline.ignoreResult();
+  }
+};
+
+// `Fetcher` actually wants us to give it a factory that creates a new `WorkerInterface` for each
+// request, so this is that.
+class Container::TcpPortOutgoingFactory final: public Fetcher::OutgoingFactory {
+ public:
+  TcpPortOutgoingFactory(capnp::ByteStreamFactory& byteStreamFactory,
+      const kj::HttpHeaderTable& headerTable,
+      rpc::Container::Port::Client port)
+      : byteStreamFactory(byteStreamFactory),
+        headerTable(headerTable),
+        port(kj::mv(port)) {}
+
+  kj::Own<WorkerInterface> newSingleUseClient(kj::Maybe<kj::String> cfStr) override {
+    // At present we have no use for `cfStr`.
+    return kj::heap<TcpPortWorkerInterface>(byteStreamFactory, headerTable, port);
+  }
+
+ private:
+  capnp::ByteStreamFactory& byteStreamFactory;
+  const kj::HttpHeaderTable& headerTable;
+  rpc::Container::Port::Client port;
+};
+
+jsg::Ref<Fetcher> Container::getTcpPort(jsg::Lock& js, int port) {
+  JSG_REQUIRE(port > 0 && port < 65536, TypeError, "Invalid port number: ", port);
+
+  auto req = rpcClient->getTcpPortRequest(capnp::MessageSize{4, 0});
+  req.setPort(port);
+
+  auto& ioctx = IoContext::current();
+
+  kj::Own<Fetcher::OutgoingFactory> factory = kj::heap<TcpPortOutgoingFactory>(
+      ioctx.getByteStreamFactory(), ioctx.getHeaderTable(), req.send().getPort());
+
+  return jsg::alloc<Fetcher>(
+      ioctx.addObject(kj::mv(factory)), Fetcher::RequiresHostAndProtocol::YES, true);
+}
+
+}  // namespace workerd::api

src/workerd/api/container.h

@@ -0,0 +1,71 @@
+// Copyright (c) 2025 Cloudflare, Inc.
+// Licensed under the Apache 2.0 license found in the LICENSE file or at:
+//     https://opensource.org/licenses/Apache-2.0
+
+#pragma once
+// APIs that an Actor (Durable Object) uses to access its own state.
+//
+// See actor.h for APIs used by other Workers to talk to Actors.
+
+#include <workerd/io/container.capnp.h>
+#include <workerd/io/io-own.h>
+#include <workerd/jsg/jsg.h>
+
+namespace workerd::api {
+
+class Fetcher;
+
+class Container: public jsg::Object {
+ public:
+  Container(rpc::Container::Client rpcClient);
+
+  struct StartupOptions {
+    jsg::Optional<kj::Array<kj::String>> entrypoint;
+    bool enableInternet = false;
+
+    // TODO(containers): stdio interception
+
+    JSG_STRUCT(entrypoint, enableInternet);
+  };
+
+  bool getRunning() {
+    return running;
+  }
+
+  // Methods correspond closely to the RPC interface in `container.capnp`.
+  void start(jsg::Lock& js, jsg::Optional<StartupOptions> options);
+  jsg::Promise<void> monitor(jsg::Lock& js);
+  jsg::Promise<void> destroy(jsg::Lock& js, jsg::Optional<jsg::Value> error);
+  void signal(jsg::Lock& js, int signo);
+  jsg::Ref<Fetcher> getTcpPort(jsg::Lock& js, int port);
+
+  // TODO(containers): listenTcp()
+
+  JSG_RESOURCE_TYPE(Container) {
+    JSG_READONLY_PROTOTYPE_PROPERTY(running, getRunning);
+    JSG_METHOD(start);
+    JSG_METHOD(monitor);
+    JSG_METHOD(destroy);
+    JSG_METHOD(signal);
+    JSG_METHOD(getTcpPort);
+  }
+
+ private:
+  IoOwn<rpc::Container::Client> rpcClient;
+
+  // TODO(containers): Actually check if the container is already running when the DO starts.
+  bool running = false;
+
+  kj::Maybe<jsg::Value> destroyReason;
+
+  void visitForGc(jsg::GcVisitor& visitor) {
+    visitor.visit(destroyReason);
+  }
+
+  class TcpPortWorkerInterface;
+  class TcpPortOutgoingFactory;
+};
+
+#define EW_CONTAINER_ISOLATE_TYPES api::Container, api::Container::StartupOptions
+
+}  // namespace workerd::api

src/workerd/io/BUILD.bazel

@@ -98,6 +98,7 @@ wd_cc_library(
         ":actor-id",
         ":actor-storage_capnp",
         ":cdp_capnp",
+        ":container_capnp",
         ":frankenvalue",
         ":io-gate",
         ":io-helpers",
@@ -303,6 +304,13 @@ wd_capnp_library(src = "features.capnp")
 
 wd_capnp_library(src = "frankenvalue.capnp")
 
+wd_capnp_library(
+    src = "container.capnp",
+    deps = [
+        "@capnp-cpp//src/capnp/compat:byte-stream_capnp",
+    ],
+)
+
 kj_test(
     src = "io-gate-test.c++",
     deps = [