feat(cloudflare): Add trace propagation for RPC method calls#20343
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feat(cloudflare): Add trace propagation for RPC method calls#20343
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Moved to draft, as tests are failing and I have to change 1-2 things that could reduce the amount lines added |
JPeer264
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…pagation (#20345) follow up to #19991 It is better to release it first with an option to be enabled, that would then also be in line with #20343, otherwise `.fetch()` RPC calls would work without any option and the actual Cap'n'Proto RPC calls wouldn't work without. That would be an odd experience. ### New option: `enableRpcTracePropagation` > `instrumentPrototypeMethods` has been deprecated in favor of `enableRpcTracePropagation` Replaces the deprecated `instrumentPrototypeMethods` option with a clearer name that describes what it actually does. This option must be enabled on **both** the caller (Worker) and receiver (Durable Object) sides for trace propagation to work. It is also worth to mention that the implementation of "instrumenting prototype methods" has changed to a Proxy. ```ts // Worker side export default Sentry.withSentry( (env) => ({ dsn: env.SENTRY_DSN, enableRpcTracePropagation: true, }), handler, ); // Durable Object side export const MyDurableObject = Sentry.instrumentDurableObjectWithSentry( (env) => ({ dsn: env.SENTRY_DSN, enableRpcTracePropagation: true, }), MyDurableObjectBase, ); ```
andreiborza
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Apr 20, 2026
…pagation (#20345) follow up to #19991 It is better to release it first with an option to be enabled, that would then also be in line with #20343, otherwise `.fetch()` RPC calls would work without any option and the actual Cap'n'Proto RPC calls wouldn't work without. That would be an odd experience. ### New option: `enableRpcTracePropagation` > `instrumentPrototypeMethods` has been deprecated in favor of `enableRpcTracePropagation` Replaces the deprecated `instrumentPrototypeMethods` option with a clearer name that describes what it actually does. This option must be enabled on **both** the caller (Worker) and receiver (Durable Object) sides for trace propagation to work. It is also worth to mention that the implementation of "instrumenting prototype methods" has changed to a Proxy. ```ts // Worker side export default Sentry.withSentry( (env) => ({ dsn: env.SENTRY_DSN, enableRpcTracePropagation: true, }), handler, ); // Durable Object side export const MyDurableObject = Sentry.instrumentDurableObjectWithSentry( (env) => ({ dsn: env.SENTRY_DSN, enableRpcTracePropagation: true, }), MyDurableObjectBase, ); ```
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closes #19327
closes JS-1715
closes #16898
closes JS-680
closes #16760
closes JS-622
Summary
Adds trace propagation for Cloudflare Workers RPC method calls to Durable Objects.
This is admittedly a bit of a hack: Cap'n Proto (which powers Cloudflare RPC) has no native support for headers or metadata. To work around this, we append our trace data (sentry-trace + baggage) as a trailing argument object
{ __sentry: { trace, baggage } }to every RPC call. On the receiving DO side, we strip this argument before the user's method is invoked, so it's completely transparent.Caveat: If the Durable Object is not instrumented with Sentry, the trailing
__sentryargument will remain in the args array and be passed to the user's method. I would count this as ok since:...argsto retrieve all argumentsOtherwise, trace propagation should be seamless across Worker → DO and Worker → Worker → DO call chains.
How it works
As mentioned above a Sentry trace object is appended on each call