gRPC-Web Bridge for Caddy

This module implements a bridge from gRPC-Web clients to gRPC servers. It is similar to Envoy's envoy.filters.http.grpc_web filter. It is EXPERIMENTAL and subject to change.

To convert gRPC-Web requests to gRPC, simply add the grpc_web handler to your HTTP route. It should go before your reverse_proxy or any other handler that would expect a gRPC request.

Installation

A new Caddy server with this module needs to be built to support GRPC-web calls. Build it with:

docker build -t <account_name>/caddy-grpc .

Example

Caddyfile:

{
	order grpc_web before reverse_proxy
}

:5452 {
	grpc_web
	reverse_proxy h2c://127.0.0.1:50051
}

JSON:

{
	"apps": {
		"http": {
			"servers": {
				"srv0": {
					"listen": [
						":5452"
					],
					"routes": [
						{
							"handle": [
								{
									"handler": "grpc_web"
								},
								{
									"handler": "reverse_proxy",
									"transport": {
										"protocol": "http",
										"versions": [
											"h2c",
											"2"
										]
									},
									"upstreams": [
										{
											"dial": "127.0.0.1:50051"
										}
									]
								}
							]
						}
					]
				}
			}
		}
	}
}

You can also specify the websocket_ping parameter to an interval value >= 1s for websocket keep-alive pings to be enabled.