Add proxy preset: transparent (#881)

* Add reverse_proxy preset

* Update to 'transparent' preset instead of 'reverse_proxy'

caddyhttp/proxy/upstream.go

@@ -260,6 +260,10 @@ func parseBlock(c *caddyfile.Dispenser, u *staticUpstream) error {
 			return c.ArgErr()
 		}
 		u.downstreamHeaders.Add(header, value)
+	case "transparent":
+		u.upstreamHeaders.Add("Host", "{host}")
+		u.upstreamHeaders.Add("X-Real-IP", "{remote}")
+		u.upstreamHeaders.Add("X-Forwarded-Proto", "{scheme}")
 	case "websocket":
 		u.upstreamHeaders.Add("Connection", "{>Connection}")
 		u.upstreamHeaders.Add("Upgrade", "{>Upgrade}")

caddyhttp/proxy/upstream_test.go

 package proxy
 
 import (
+	"strings"
 	"testing"
 	"time"
+
+	"github.com/mholt/caddy/caddyfile"
 )
 
 func TestNewHost(t *testing.T) {
@@ -133,3 +136,40 @@ func TestAllowedPaths(t *testing.T) {
 		}
 	}
 }
+
+func TestParseBlock(t *testing.T) {
+	tests := []struct {
+		config string
+	}{
+		// Test #1: transparent preset
+		{"proxy / localhost:8080 {\n transparent \n}"},
+
+		// Test #2: transparent preset with another param
+		{"proxy / localhost:8080 {\n transparent \nproxy_header X-Test Tester \n}"},
+
+		// Test #3: transparent preset on multiple sites
+		{"proxy / localhost:8080 {\n transparent \n} \nproxy /api localhost:8081 { \ntransparent \n}"},
+	}
+
+	for i, test := range tests {
+		upstreams, err := NewStaticUpstreams(caddyfile.NewDispenser("Testfile", strings.NewReader(test.config)))
+		if err != nil {
+			t.Error("Expected no error. Got:", err.Error())
+		}
+		for _, upstream := range upstreams {
+			headers := upstream.Select().UpstreamHeaders
+
+			if _, ok := headers["Host"]; !ok {
+				t.Errorf("Test %d: Could not find the Host header", i+1)
+			}
+
+			if _, ok := headers["X-Real-Ip"]; !ok {
+				t.Errorf("Test %d: Could not find the X-Real-Ip header", i+1)
+			}
+
+			if _, ok := headers["X-Forwarded-Proto"]; !ok {
+				t.Errorf("Test %d: Could not find the X-Forwarded-Proto header", i+1)
+			}
+		}
+	}
+}