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Caddy grpc

grpc plugin for Caddy Server

grpc makes it possible for gRPC services to be consumed from browsers using the gRPC-Web protocol and normal gRPC clients. (If the request is not a grpc-web request, it will be served as a normal grpc request)

The plugin is meant to serve the same purpose as grpcwebproxy by Improbable, but as a Caddy middleware plugin instead of a standalone Go application.

Downloading

The plugin will be available to download as a plugin from Caddy's Download page. Click on Add plugins option and scroll down to the section where you can tick the http.grpc box.

To verify the plugin is part of your downloaded instance of Caddy, run Caddy with the -plugins command line flag: caddy -plugins

http.grpc should be listed under Other plugins along with http and any other plugins also included.

Note, because the plugin is still in development it's not yet available on the Caddy download page

Roadmap/TODO

  • Inject Go gRPC Middleware into the underlying gRPC proxy using the Caddyfile.
  • Load balancing features

Proposed Caddyfile

example.com 
grpc localhost:9090

The first line example.com is the hostname/address of the site to serve. The second line is a directive called grpc where the backend gRPC service endpoint address (i.e localhost:9090 as in the example) can be specified. (Note: The above configuration will default to having TLS 1.2 to the backend gRPC service)

Caddyfile syntax

grpc backend_addr {
    backend_is_insecure 
    backend_tls_noverify
    backend_tls_ca_files path_to_ca_file1 path_to_ca_file2 
}

backend_is_insecure

By default the proxy will connect to backend using TLS, however if the backend is serving in plaintext this option need to be added

backend_tls_noverify

By default the TLS to the backend will be verified, however if this is not the case then this option need to be added

backend_tls_ca_files

Paths (comma separated) to PEM certificate chains used for verification of backend certificates. If empty, host CA chain will be used.

Caddyfile example with other directives

grpc.example.com 
prometheus
log
grpc localhost:9090

Status

This plugin is in BETA

grpc-web client implementations/examples

Javascript and Typescript

Vue.js

GopherJS

References

Extending Caddy

Writing a Plugin: Directives

Caddyfile

gRPC

grpcwebproxy

gRPC-Web protocol

gRPC-Web: Moving past REST+JSON towards type-safe Web APIs