Implement connection props. #3193

kentonv · 2024-11-29T23:12:33Z

This adds ctx.props to the ctx object given to WorkerEntrypoints. The property receives metadata about the particular service binding over which the entrypoint was invoked.

class MyEntrypoint extends WorkerEntrypoint {
  foo() {
    console.log("called by: " + this.ctx.props.caller);
  }
}

Service binding declarations in the workerd config may specify what metadata to pass:

bindings = [
  ( name = "FOO",
    service = (
      name = "my-service",
      entrypoint = "MyEntrypoint",
      props = (
        json = `{"caller": "my-calling-service"}
      )
    )
  )
]

Note that "caller" is just an example. The props can contain anything. Use cases include:

Authentication of the caller's identity.
Authorization / permissions (independent of caller identity).
Specifying a particular resource. For example, if the WorkerEntrypoint represents a chat room, props.roomId could be the ID of the specific chat room to access.

This allows service bindings to implement a deeper capability-based security model, where bindings point to specific resources with specific permissions, instead of general APIs.

On Cloudflare, only users who have permission to modify your worker will have permission to create a binding containing arbitrary metadata. Meanwhile we will be creating a mechanism by which you can grant a service binding to your worker to someone, but where you specify the metadata. Thus, you can use the metadata to authenticate requests, without the need for any cryptography.

kentonv · 2024-11-29T23:14:33Z

I'm not entirely happy that every CustomEvent implementation had to change here. I might go back and try a different approach to reduce the noise a bit.

kentonv · 2024-12-06T16:48:55Z

OK this is ready for review!

It was auto-assigned to @harrishancock but he already owes me other reviews so I removed him and added @jp4a50 instead.

kentonv · 2024-12-06T19:20:42Z

Last push was fixup: b9c6609

jasnell · 2024-12-06T21:45:26Z

src/workerd/api/global-scope.h

+
+  void visitForGc(jsg::GcVisitor& visitor) {
+    visitor.visit(props);
+  }


Non-blocking nit: this should likely implement visitForMemoryInfo(...) also

src/workerd/io/frankenvalue.h

src/workerd/io/worker.c++

jp4a50

LGTM

jp4a50 · 2024-12-09T18:26:06Z

src/workerd/io/frankenvalue.capnp

+  # be an object. Each property in this list must have a `name`. They will be added as properties
+  # of the object.
+  #
+  # If a property in the list concflicts with a property that already exists in the base value,


[typo] concflicts

src/workerd/io/frankenvalue.h

jp4a50 · 2024-12-09T19:35:38Z

src/workerd/api/global-scope.h

  JSG_RESOURCE_TYPE(ExecutionContext, CompatibilityFlags::Reader flags) {
    JSG_METHOD(waitUntil);
    JSG_METHOD(passThroughOnException);
+    JSG_LAZY_INSTANCE_PROPERTY(props, getProps);


What's the rationale for this being read-write instead of read-only?

Performance: A lazy instance property becomes a regular JS property after the first access, which can then be optimized better if it is accessed repeatedly. A regular property would have to call back to C++ for every access.

I think the question was more: Why JSG_LAZY_INSTANCE_PROPERTY and not JSG_LAZY_READYONLY_INSTANCE_PROPERTY... you'd get the same lazy replacement either way. Tho, marking the field read only does have an ever so slight performance impact.

src/workerd/io/worker-entrypoint.c++

kentonv · 2024-12-10T22:18:08Z

Fixups:

Currently, `ServiceDesignator` can only resolve to one of a fixed set of objects that already exist, but we want to make it a little bit more dynamic in later commits.

This will allow us to extend it to support connection metadata, which might be different for each binding pointing to the same entrypoint.

See comments for description.

This adds `ctx.props` to the `ctx` object given to `WorkerEntrypoint`s. The property receives metadata about the particular service binding over which the entrypoint was invoked. ``` class MyEntrypoint extends WorkerEntrypoint { foo() { console.log("called by: " + this.ctx.props.caller); } } ``` Service binding declarations in the workerd config may specify what metadata to pass: ``` bindings = [ ( name = "FOO", service = ( name = "my-service", entrypoint = "MyEntrypoint", props = ( json = `{"caller": "my-calling-service"} ) ) ) ] ``` Note that "caller" is just an example. The props can contain anything. Use cases include: * Authentication of the caller's identity. * Authorization / permissions (independent of caller identity). * Specifying a particular resource. For example, if the `WorkerEntrypoint` represents a chat room, `props.roomId` could be the ID of the specific chat room to access. This allows service bindings to implement a deeper capability-based security model, where bindings point to specific resources with specific permissions, instead of general APIs. On Cloudflare, only users who have permission to modify your worker will have permission to create a binding containing arbitrary metadata. Meanwhile we will be creating a mechanism by which you can grant a service binding to your worker to someone, but where you specify the metadata. Thus, you can use the metadata to authenticate requests, without the need for any cryptography.

jasnell · 2024-12-10T22:28:15Z

src/workerd/io/frankenvalue.h

+  //
+  // This is called `set` because the new property will override any existing property with the
+  // same name, but note that this strictly appends content. The replacement happens only when the
+  // Frankenvalue is finally converted to JS.


Non-blocking nit: It's likely worth documenting that toJs(...) will throw if there are properties added but the realized JS value is not actually an object.

jasnell · 2024-12-10T22:29:53Z

src/workerd/io/frankenvalue.h

+  struct Json {
+    kj::String json;
+  };
+  struct V8Serialized {
+    kj::Array<byte> data;
+  };


Non-blocking nit: Since these are just single valued, structs this might be a bit cleaner:

using Json = kj::String; using V8Serialized = kj::Array<kj::byte>;

kentonv requested a review from geelen November 29, 2024 23:12

kentonv added the needs-internal-pr label Nov 29, 2024

kentonv force-pushed the kenton/connection-meta branch from 20274fa to bb2b4f6 Compare December 6, 2024 16:30

kentonv changed the title ~~[WIP] Implement connection metadata.~~ Implement connection props. Dec 6, 2024

kentonv marked this pull request as ready for review December 6, 2024 16:33

kentonv requested review from a team as code owners December 6, 2024 16:33

kentonv requested review from harrishancock, vickykont and jp4a50 and removed request for harrishancock December 6, 2024 16:33

kentonv force-pushed the kenton/connection-meta branch from bb2b4f6 to a03109c Compare December 6, 2024 16:47

kentonv removed the needs-internal-pr label Dec 6, 2024

kentonv force-pushed the kenton/connection-meta branch 2 times, most recently from b9c6609 to dc08c4f Compare December 6, 2024 19:20

kentonv requested a review from a team as a code owner December 6, 2024 21:19

jasnell reviewed Dec 6, 2024

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kentonv force-pushed the kenton/connection-meta branch from 7f6d4cf to 1744eac Compare December 10, 2024 22:17

kentonv added 4 commits December 10, 2024 16:18

Refactor server.c++: Make lookupService() return Own<Service>.

c8f6377

Currently, `ServiceDesignator` can only resolve to one of a fixed set of objects that already exist, but we want to make it a little bit more dynamic in later commits.

Refactor server.c++: Construct EntrypointService on-demand.

f16bdd4

This will allow us to extend it to support connection metadata, which might be different for each binding pointing to the same entrypoint.

Add Frankenvalue type: A stitched-together JS value.

3837d4e

See comments for description.

Update types snapshot to include ctx.props.

c2cce70

kentonv force-pushed the kenton/connection-meta branch from 1744eac to c2cce70 Compare December 10, 2024 22:18

jasnell reviewed Dec 10, 2024

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jasnell approved these changes Dec 10, 2024

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kentonv merged commit 7518bb8 into main Dec 11, 2024
15 checks passed

kentonv deleted the kenton/connection-meta branch December 11, 2024 00:08

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Implement connection props. #3193

Implement connection props. #3193

kentonv commented Nov 29, 2024 •

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Implement connection props. #3193

Implement connection props. #3193

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