The gRPC proxy module.

The module allows passing requests to upstream gRPC servers.
The module is built by default as long as HTTP/2 support is compiled in.
Example configuration:

    grpc_pass 127.0.0.1:9000;

Alternatively, the "grpc://" scheme can be used:

    grpc_pass grpc://127.0.0.1:9000;

Keepalive support is available via the upstream keepalive module.  Note
that keepalive connections won't currently work with grpc-go as it fails
to handle SETTINGS_HEADER_TABLE_SIZE.

To use with SSL:

    grpc_pass grpcs://127.0.0.1:9000;

SSL connections use ALPN "h2" when available.  At least grpc-go works fine
without ALPN, so if ALPN is not available we just establish a connection
without it.

Tested with grpc-c++ and grpc-go.

auto/modules

@@ -744,6 +744,17 @@ if [ $HTTP = YES ]; then
         . auto/module
     fi
 
+    if [ $HTTP_GRPC = YES -a $HTTP_V2 = YES ]; then
+        ngx_module_name=ngx_http_grpc_module
+        ngx_module_incs=
+        ngx_module_deps=
+        ngx_module_srcs=src/http/modules/ngx_http_grpc_module.c
+        ngx_module_libs=
+        ngx_module_link=$HTTP_GRPC
+
+        . auto/module
+    fi
+
     if [ $HTTP_PERL != NO ]; then
         ngx_module_name=ngx_http_perl_module
         ngx_module_incs=src/http/modules/perl

auto/options

@@ -86,6 +86,7 @@ HTTP_PROXY=YES
 HTTP_FASTCGI=YES
 HTTP_UWSGI=YES
 HTTP_SCGI=YES
+HTTP_GRPC=YES
 HTTP_PERL=NO
 HTTP_MEMCACHED=YES
 HTTP_LIMIT_CONN=YES
@@ -262,6 +263,7 @@ $0: warning: the \"--with-ipv6\" option is deprecated"
         --without-http_fastcgi_module)   HTTP_FASTCGI=NO            ;;
         --without-http_uwsgi_module)     HTTP_UWSGI=NO              ;;
         --without-http_scgi_module)      HTTP_SCGI=NO               ;;
+        --without-http_grpc_module)      HTTP_GRPC=NO               ;;
         --without-http_memcached_module) HTTP_MEMCACHED=NO          ;;
         --without-http_limit_conn_module) HTTP_LIMIT_CONN=NO        ;;
         --without-http_limit_req_module) HTTP_LIMIT_REQ=NO         ;;