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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.


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


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

Proposed Caddyfile 
grpc localhost:9090

The first line 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_tls_ca_files path_to_ca_file1 path_to_ca_file2 


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


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


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 localhost:9090


This plugin is in BETA

grpc-web client implementations/examples

Javascript and Typescript




Extending Caddy

Writing a Plugin: Directives




gRPC-Web protocol

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