question: How to get client IP and custom headers in Lua filter

[nic-chen]

I am developing a framework that support Apache APISIX plugins run directly in Envoy Lua filter without modify Envoy. #13307

But in the process, I found that some header values, such as client IP and custom headers, cannot be get in Lua filter.

I think client IP and custom headers should be very commonly used.

I might misreading/misunderstanding, but I don't know how to get them, please remind me, thank you !

[dio]

I found that some header values, such as client IP and custom headers, cannot be get in Lua filter.

Sorry, do you mean you have this information available on headers but it was not there when you tried to access it?

FWIW, I think the information is available here:

envoy/include/envoy/stream_info/stream_info.h

Lines 474 to 479 in 319a9a6

	/**
	* @return the downstream remote address. Note that this will never be nullptr. This may be
	* equivalent to downstreamDirectRemoteAddress, unless the remote address is inferred from a
	* proxy proto, x-forwarded-for, etc.
	*/
	virtual const Network::Address::InstanceConstSharedPtr& downstreamRemoteAddress() const PURE;

However, yes currently we have the StreamInfo wrapper but not all information is accessible from Lua script.

[nic-chen]

Sorry, do you mean you have this information available on headers but it was not there when you tried to access it?

I reconfirmed that the custom headers are available by handle:headers(), sorry about that.

However, yes currently we have the StreamInfo wrapper but not all information is accessible from Lua script.

It seems that only protocol, dynamicMetadata and downstreamSslConnection are exposed.
Would We export downstreamRemoteAddress to Lua filter ? 😃

[dio]

@nic-chen sure. I think this is a good exercise for a new contributor. Do you want to try? I can try to help with providing guidance and review. Here is a complete (well, it's still missing docs) patch to expose downstream local address: https://github.com/envoyproxy/envoy/compare/master...dio:lua-streaminfo-addresss?expand=1, you can then add more getters to StreamInfoWrapper as you wish 🙂.

[nic-chen]

@nic-chen sure. I think this is a good exercise for a new contributor. Do you want to try? I can try to help with providing guidance and review. Here is a complete (well, it's still missing docs) patch to expose downstream local address: https://github.com/envoyproxy/envoy/compare/master...dio:lua-streaminfo-addresss?expand=1.

Wow, so nice you are!

I have always used JAVA, PHP, GO, Lua, JavaScript to work, and have never used C++.

But I would like to try it out and learn, hoping to contribute more in the future.

[nic-chen]

@nic-chen sure. I think this is a good exercise for a new contributor. Do you want to try? I can try to help with providing guidance and review. Here is a complete (well, it's still missing docs) patch to expose downstream local address: https://github.com/envoyproxy/envoy/compare/master...dio:lua-streaminfo-addresss?expand=1, you can then add more getters to StreamInfoWrapper as you wish 🙂.

Do you mind if I push directly to your repo? Or should I submit the code on my repo? Then create a pr.
Thanks !

[dio]

@nic-chen I think I prefer for you to work on your own repo. Please note that the patch that I have exposes downstream local address, which probably not what you want. You can of course expose more, since the pattern will be the same (the remote ones: downstreamRemoteAddress(), downstreamDirectRemoteAddress(), etc).

Have you successfully built envoy on your local? Please let me know if you have any issues.

You can follow the official docs https://github.com/envoyproxy/envoy/blob/8a1d44422ba9ffa303c89b109b57e8889655b53a/bazel/README.md#building-envoy-with-bazel on building it, or the short one here (if you're on Linux (Debian-based) and want to use clang): https://gist.github.com/dio/9a7c826a2dbf004a81112db0d167d209.

[nic-chen]

@dio
OK. Thanks so much.

I will try to build and make some test.

It may take some time. There should be issues in this process that need your help, if so, I will ping you here. : )

[nic-chen]

@dio

I works on macOS, so took some time to build..

I think i could submit a pr today or tomorrow.