How to enable external Caddy Plugins

The below explains how to enabled external caddy plugins. Here, caddyserver/forwardproxy plugin is being enabled.

First, get Golang:

cd /usr/local &&
curl -s -L -O https://dl.google.com/go/go1.10.1.linux-amd64.tar.gz
tar -xvzf go1.10.1.linux-amd64.tar.gz

Next, add the following ~/.bash_profile:

export GOPATH=$HOME/go
export GOBIN=$HOME/go/bin
export GOROOT=/usr/local/go

Also, add GOBIN to the PATH environment variable:

PATH=$GOBIN:$PATH
export PATH

After this step, you have Golang compiler ready in /usr/local/go/bin/ directory:

# /usr/local/go/bin/go version
go version go1.10.1 linux/amd64

Download the source code of caddy and caddyserver/forwardproxy plugin:

go get github.com/mholt/caddy/caddy
go get github.com/caddyserver/builds
go get github.com/caddyserver/forwardproxy

Add a reference to caddyserver/forwardproxy plugin in caddy source code. Find "This is where other plugins get plugged in" in $GOPATH/src/github.com/mholt/caddy/caddy/caddymain/run.go file and add a reference to the plugin.

_ "github.com/caddyserver/forwardproxy"

Finally, build caddy binary:

cd $GOPATH/src/github.com/mholt/caddy/caddy
go run build.go
caddy --version

The http.forwardproxy plugin is in the list of enabled plugins:

# caddy -plugins
Server types:
  http

Caddyfile loaders:
  short
  flag
  default

Other plugins:
  http.forwardproxy