caddy proxy

Caddyfile

(cors) {
  @cors_preflight method OPTIONS
  @cors header Origin {args.0}

  handle @cors_preflight {
    header Access-Control-Allow-Origin "{args.0}"
    header Access-Control-Allow-Methods "GET, POST, PUT, PATCH, DELETE"
    header Access-Control-Allow-Headers "Content-Type"
    header Access-Control-Max-Age "3600"
    respond "" 204
  }

  handle @cors {
    header Access-Control-Allow-Origin "{args.0}"
    header Access-Control-Expose-Headers "Link"
  }
}

:8081 {
  import cors http://0.0.0.0:8081
  reverse_proxy localhost:3000
}

gistfile1.txt

:8081 {
    @options {
        method OPTIONS
    }
    header {
        Access-Control-Allow-Origin *
        Access-Control-Allow-Credentials true
        Access-Control-Allow-Methods *
        Access-Control-Allow-Headers *
        defer
    }
    reverse_proxy localhost:8080 {
        header_down -Access-Control-Allow-Origin
    }
    respond @options 204
}