gRPC - Request/Response body as byte array/JSON

[ashoke-cube]

I have set up a lua filter for accessing the request/response details [headers and body] for a gRPC service. I am able to see proper headers data. The request/response data is of the form 'userdata : xxxxxxxxxxx'

For example:

print (request_handle:body()) -> userdata: 0x40dae6a0

1. Is there a utility to get the data in byte array/JSON format?
2. I understand the conversion requires .proto files, how do I specify it in the filter?

[dio]

I'm started to think probably we need to consolidate C++ implemented utilities (that is exposed to the Lua world) into a dedicated "wrapper", either to be attached to the stream handle or available globally.

We see e.g.

1. lua API: add base64Escape function to stream handle #12552 to add base64 encoding helper
2. lua: timestamp in millis #10329 to add timestamping helper
3. This issue to add get JSON string from a protobuf message (this request also can be implemented in C++, using MessageUtil::getJsonStringFromMessage)

If attaching to stream handler wrapper is preferred (this is in line with httpCall):

function envoy_on_request(request_handle) {
  request_handle:utility():base64Encode("ok");
  request_handle:utility():currentTimestamp();
  request_handle:utility():getJsonStringFromProtoMessageBuffer(request_handle.body());
}

Or if we prefer it to be available globally, since the functionality doesn't need access to the current stream.

function envoy_on_request(request_handle) {
  envoyBase64Encode("ok");
  envoyCurrentTimestamp();
  envoyGetJsonStringFromProtoMessageBuffer(request_handle.body());
}

cc. @mattklein123 @mpuncel

[mattklein123]

Sure all of that SGTM @dio

[paawan01]

Is there anything currently available to achieve this in lua filter ?

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This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or other activity occurs. Thank you for your contributions.

[dio]

@paawan01 you can get the data "bytes", via getBytes() API.

request_handle:body() doesn't return a string. It returns a buffer wrapper.

Hence a call to it ends up with a value that looks like userdata: 0x40dae6a0

Try this instead:

local body = request_handle:body()
local bytes = tostring(body:getBytes(0, body:length()))

But yeah you can't really work with the encoded protobuf messages in Lua yet, but you can forward that data to another service.

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[github-actions]

This issue has been automatically closed because it has not had activity in the last 37 days. If this issue is still valid, please ping a maintainer and ask them to label it as "help wanted" or "no stalebot". Thank you for your contributions.