How can I get gRPC Metadata (or said Response trailers) in Kong plugin ?

[jluncc]

what i had try:

1. kong.response.get_header(name)
2. kong.service.response.get_header(name)
3. ngx.header[name]

both can not work, so if anyone konw how to get the gRPC response Metadata value (Response trailers value) in the Kong plugin ?

[StarlightIbuki]

The metadata could be located in trailers, which PDK does not support to extract for now. A workaround could be to get the raw socket, read the raw request/response stream and parse the body.

[jluncc]

thanks for your answer

i am new to lua and kong plugin develop, can u give me some example code or key words to search ?

[StarlightIbuki]

https://github.com/openresty/lua-nginx-module#ngxreqsocket
It's pretty tricky to do this manually, a starting point could be: https://github.com/brimworks/lua-http-parser

[jluncc]

i will study it first, thank you

[jenstroeger]

@StarlightIbuki any plans to add support for reading trailing metadata of gRPC response messages?