This is a small reverse proxy that can front existing gRPC servers and expose their functionality using gRPC-Web protocol, allowing for the gRPC services to be consumed from browsers.

Features:

• structured logging of proxied requests to stdout
• debug HTTP endpoint (default on port 8080)
• Prometheus monitoring of proxied requests (/metrics on debug endpoint)
• Request (/debug/requests) and connection tracing endpoints (/debug/events)
• TLS 1.2 serving (default on port 8443):
  • with option to enable client side certificate validation
• both secure (plaintext) and TLS gRPC backend connectivity:
  • with customizable CA certificates for connections

The indented use is as a companion process for gRPC server containers.

To install, you need to have Go >= 1.8, and call go get:

go get -u github.com/improbable-eng/grpc-web/go/grpcwebproxy

Here's a simple example that fronts a local, TLS gRPC server:

$GOPATH/bin/grpcwebproxy
    --server_tls_cert_file=../../misc/localhost.crt \
    --server_tls_key_file=../../misc/localhost.key \
    --backend_addr=localhost:9090 \
    --backend_tls_noverify

By default, grpcwebproxy will run both TLS and HTTP debug servers. To disable either one, set the --run_http_server or --run_tls_server flags to false.

For example, to only run the HTTP server, run the following:

$GOPATH/bin/grpcwebproxy
    --backend_addr=localhost:9090 \
    --run_tls_server=false

By default, grpcwebproxy will not use websockets as a transport layer. To enable websockets, set the --use_websockets flag to true.

$GOPATH/bin/grpcwebproxy \
    --backend_addr=localhost:9090 \
    --use_websockets