[OP Stack Deployment] Proxyd header forwarding

[srounce]

Did you check the documentation?

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• Yes

Issue Description

I wasn't able to see how to configure Proxyd to forward headers from the upstream RPC(s). Is there a way to do this (specifically CORS headers) or will this have to be implemented?

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[hash1go]

Based on the linked code, there is no functionality that forwards headers from the upstream RPC responses, including CORS headers. The code only sets the Content-Type header for the response. If you need CORS headers to be forwarded, this would have to be implemented separately.

https://github.com/ethereum-optimism/infra/blob/3753db77dc894319914685eb35e893ef8253b9f6/proxyd/backend.go#L314
https://github.com/ethereum-optimism/infra/blob/3753db77dc894319914685eb35e893ef8253b9f6/proxyd/server.go#L763
https://github.com/ethereum-optimism/infra/blob/3753db77dc894319914685eb35e893ef8253b9f6/proxyd/backend.go#L357

[hash1go]

@srounce cc: @opfocus
Since there's been no further response, I suggest using Nginx as a reverse proxy to handle CORS headers forwarding. There are many examples available for configuring Nginx for this purpose.

[srounce]

Hi sorry for the silence, yes that's what I did in the end but it just adds an additional moving part which I'd have rather avoided but it did the job.

[Chomtana]

https://github.com/ethereum-optimism/infra/blob/e10211331a1114607227ea0acdc40ed7f5568b81/proxyd/config.go#L31

I have seen there is an AllowAllOrigins config. Have you enabled that?

[hash1go]

Thanks for pointing this out. However, AllowAllOrigins is specifically for WebSocket origin checking, not for forwarding CORS headers from upstream RPC responses. But depending on the specific issue they're facing, this might still be useful information.

[opfocus]

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