feat: add support for routing an app to a specified host:port

This is useful when there is a service not managed by Dokku but should be exposed via the Dokku routing layer. As an example, some binaries (consul, nomad, vault) expose web uis, and are traditionally run on the host directly vs in a container.

Closes #4665

plugins/network/network.go

@@ -3,6 +3,7 @@ package network
 import (
 	"fmt"
 	"io/ioutil"
+	"net"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -17,18 +18,19 @@ import (
 var (
 	// DefaultProperties is a map of all valid network properties with corresponding default property values
 	DefaultProperties = map[string]string{
-		"bind-all-interfaces": "",
 		"attach-post-create":  "",
 		"attach-post-deploy":  "",
+		"bind-all-interfaces": "",
 		"initial-network":     "",
+		"static-web-listener": "",
 		"tld":                 "",
 	}
 
 	// GlobalProperties is a map of all valid global network properties
 	GlobalProperties = map[string]bool{
-		"bind-all-interfaces": true,
 		"attach-post-create":  true,
 		"attach-post-deploy":  true,
+		"bind-all-interfaces": true,
 		"initial-network":     true,
 		"tld":                 true,
 	}
@@ -40,6 +42,10 @@ func BuildConfig(appName string) error {
 		return nil
 	}
 
+	if staticWebListener := reportStaticWebListener(appName); staticWebListener != "" {
+		return nil
+	}
+
 	appRoot := common.AppRoot(appName)
 	s, err := common.PlugnTriggerOutput("ps-current-scale", []string{appName}...)
 	if err != nil {
@@ -97,6 +103,22 @@ func BuildConfig(appName string) error {
 
 // GetContainerIpaddress returns the ipaddr for a given app container
 func GetContainerIpaddress(appName, processType, containerID string) (ipAddr string) {
+	if processType == "web" {
+		if staticWebListener := reportStaticWebListener(appName); staticWebListener != "" {
+			ip, _, err := net.SplitHostPort(staticWebListener)
+			if err == nil {
+				return ip
+			}
+
+			ip2 := net.ParseIP(staticWebListener)
+			if ip2 != nil {
+				return ip2.String()
+			}
+
+			return "127.0.0.1"
+		}
+	}
+
 	if b, err := common.DockerInspect(containerID, "{{ .HostConfig.NetworkMode }}"); err == nil {
 		if string(b[:]) == "host" {
 			return "127.0.0.1"
@@ -123,6 +145,17 @@ func GetContainerIpaddress(appName, processType, containerID string) (ipAddr str
 
 // GetContainerPort returns the port for a given app container
 func GetContainerPort(appName, processType string, containerID string, isHerokuishContainer bool) (port string) {
+	if processType == "web" {
+		if staticWebListener := reportStaticWebListener(appName); staticWebListener != "" {
+			_, port, err := net.SplitHostPort(staticWebListener)
+			if err == nil {
+				return port
+			}
+
+			return "80"
+		}
+	}
+
 	dockerfilePorts := make([]string, 0)
 	if !isHerokuishContainer {
 		configValue := config.GetWithDefault(appName, "DOKKU_DOCKERFILE_PORTS", "")
@@ -156,6 +189,12 @@ func GetContainerPort(appName, processType string, containerID string, isHerokui
 
 // GetListeners returns a string array of app listeners
 func GetListeners(appName string, processType string) []string {
+	if processType == "web" {
+		if staticWebListener := reportStaticWebListener(appName); staticWebListener != "" {
+			return []string{staticWebListener}
+		}
+	}
+
 	appRoot := common.AppRoot(appName)
 
 	ipPrefix := fmt.Sprintf("/IP.%s.", processType)