Varnish GRPC VCL

grpc.vcl

# GRPC VCL

vcl 4.0;

import bodyaccess;
import http;
import std;
import synthbackend;

backend default {
    .host = "0";
    .port = "0";
}

sub vcl_recv {
    set req.http.X-method = req.method;

    std.cache_req_body(1MB);

    if (req.method == "HEAD" || req.method == "GET" || req.method == "POST") {
        return (hash);
    }

    return (pass);
}

sub vcl_hash {
    hash_data(req.http.X-method);
    bodyaccess.hash_req_body();
}

sub vcl_backend_fetch {
    set bereq.method = bereq.http.X-method;

    http.init(0);
    http.req_set_method(0, bereq.method);
    http.req_set_url(0, "http://grpc_host:50051" + bereq.url);
    http.req_set_iparam(0, "HTTP_VERSION", 5);
    http.req_set_header(0, "te", "trailers");
    http.req_copy_headers(0);
    http.req_copy_body(0);

    http.req_send(0);
    http.resp_wait(0);

    if (http.resp_get_errorcode(0) != 0) {
        return (abandon);
    }

    set bereq.backend = synthbackend.from_blob(http.resp_get_body_blob(0));
}

sub vcl_backend_response {
    set beresp.status = http.resp_get_status(0);

    http.resp_copy_headers(0);

    if (!beresp.http.grpc-status) {
        set beresp.http.grpc-status = "0";
    }
}