support providing a configuration file for ip binding

cmd/kubefwd/kubefwd.go

@@ -48,6 +48,7 @@ func newRootCmd() *cobra.Command {
 			"  kubefwd svc -n default -l \"app in (ws, api)\"\n" +
 			"  kubefwd svc -n default -n the-project\n" +
 			"  kubefwd svc -n the-project -m 80:8080 -m 443:1443\n" +
+			"  kubefwd svc -n the-project -s path/to/conf.yml\n" +
 			"  kubefwd svc --all-namespaces",
 
 		Long: globalUsage,

cmd/kubefwd/services/services.go

@@ -56,6 +56,7 @@ var verbose bool
 var domain string
 var mappings []string
 var isAllNs bool
+var svcConfigurationPath string
 
 func init() {
 	// override error output from k8s.io/apimachinery/pkg/util/runtime
@@ -73,6 +74,7 @@ func init() {
 	Cmd.Flags().StringVarP(&domain, "domain", "d", "", "Append a pseudo domain name to generated host names.")
 	Cmd.Flags().StringSliceVarP(&mappings, "mapping", "m", []string{}, "Specify a port mapping. Specify multiple mapping by duplicating this argument.")
 	Cmd.Flags().BoolVarP(&isAllNs, "all-namespaces", "A", false, "Enable --all-namespaces option like kubectl.")
+	Cmd.Flags().StringVarP(&svcConfigurationPath, "fwd-conf", "z", "", "Define a forward configuration map")
 
 }
 
@@ -88,6 +90,7 @@ var Cmd = &cobra.Command{
 		"  kubefwd svc -n default -d internal.example.com\n" +
 		"  kubefwd svc -n the-project -x prod-cluster\n" +
 		"  kubefwd svc -n the-project -m 80:8080 -m 443:1443\n" +
+		"  kubefwd svc -n the-project -z path/to/conf.yml\n" +
 		"  kubefwd svc --all-namespaces",
 	Run: runCmd,
 }
@@ -439,6 +442,7 @@ func (opts *NamespaceOpts) AddServiceHandler(obj interface{}) {
 		SyncDebouncer:        debounce.New(5 * time.Second),
 		DoneChannel:          make(chan struct{}),
 		PortMap:              opts.ParsePortMap(mappings),
+		ServiceConfigPath:    svcConfigurationPath,
 	}
 
 	// Add the service to the catalog of services being forwarded

example.fwdconf.yml

@@ -0,0 +1,6 @@
+baseIP: 127.1.27.1
+serviceConfigurations:
+  - serviceName: service-name
+    finalOctet: 11 # 127.1.27.11
+  - serviceName: other-service-name
+    finalOctet: 99 # 127.1.27.99

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/spf13/cobra v1.1.1
 	github.com/txn2/txeh v1.2.1
 	golang.org/x/sys v0.0.0-20201112073958-5cba982894dd
+	gopkg.in/yaml.v2 v2.2.8 // indirect
 	k8s.io/api v0.20.4
 	k8s.io/apimachinery v0.20.4
 	k8s.io/cli-runtime v0.20.4

pkg/fwdIp/fwdIp.go

@@ -3,7 +3,13 @@ package fwdIp
 import (
 	"fmt"
 	"net"
+	"os"
+	"strconv"
+	"strings"
 	"sync"
+
+	log "github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v2"
 )
 
 // Registry is a structure to create and hold all of the
@@ -14,7 +20,20 @@ type Registry struct {
 	reg   map[string]net.IP
 }
 
+type ForwardConfiguration struct {
+	BaseIP                string                 `yaml:"baseIP"`
+	ServiceConfigurations []ServiceConfiguration `yaml:"serviceConfigurations"`
+}
+
+type ServiceConfiguration struct {
+	ServiceName   string `yaml:"serviceName"`
+	FinalOctet    int    `yaml:"finalOctet"`
+	FailOnOverlap bool   `yaml:"failOnOverlap"`
+}
+
 var ipRegistry *Registry
+var forwardConfiguration *ForwardConfiguration
+var defaultConfiguration = &ForwardConfiguration{BaseIP: "127.1.27.1"}
 
 // Init
 func init() {
@@ -26,7 +45,7 @@ func init() {
 	}
 }
 
-func GetIp(svcName string, podName string, clusterN int, NamespaceN int) (net.IP, error) {
+func GetIp(svcName string, podName string, clusterN int, NamespaceN int, forwardConfigurationPath string) (net.IP, error) {
 	ipRegistry.mutex.Lock()
 	defer ipRegistry.mutex.Unlock()
 
@@ -36,18 +55,97 @@ func GetIp(svcName string, podName string, clusterN int, NamespaceN int) (net.IP
 		return ip, nil
 	}
 
+	return determineIP(regKey, svcName, podName, clusterN, NamespaceN, forwardConfigurationPath), nil
+}
+
+func determineIP(regKey string, svcName string, podName string, clusterN int, NamespaceN int, forwardConfigurationPath string) net.IP {
+	baseIP := getBaseIP(forwardConfigurationPath)
+
+	// if a configuration exists use it
+	svcConf := getConfigurationForService(svcName, forwardConfigurationPath)
+	if svcConf != nil {
+		ip := net.IP{baseIP[0], baseIP[1], baseIP[2], byte(svcConf.FinalOctet)}.To4()
+		ipRegistry.reg[regKey] = ip
+		return ip
+	}
+
+	// fall back to previous implementation
 	if ipRegistry.inc[clusterN] == nil {
 		ipRegistry.inc[clusterN] = map[int]int{0: 0}
 	}
 
 	// @TODO check ranges
-	ip := net.IP{127, 1, 27, 1}.To4()
+	ip := net.IP{baseIP[0], baseIP[1], baseIP[2], baseIP[3]}.To4()
 	ip[1] += byte(clusterN)
 	ip[2] += byte(NamespaceN)
 	ip[3] += byte(ipRegistry.inc[clusterN][NamespaceN])
 
 	ipRegistry.inc[clusterN][NamespaceN]++
 	ipRegistry.reg[regKey] = ip
 
-	return ip, nil
+	return ip
+}
+
+func getBaseIP(forwardConfigurationPath string) []byte {
+	fwdCfg := getForwardConfiguration(forwardConfigurationPath)
+	ipParts := strings.Split(fwdCfg.BaseIP, ".")
+
+	octet0, err := strconv.Atoi(ipParts[0])
+	if err != nil {
+		panic("Unable to parse BaseIP octet 0")
+	}
+	octet1, err := strconv.Atoi(ipParts[1])
+	if err != nil {
+		panic("Unable to parse BaseIP octet 1")
+	}
+	octet2, err := strconv.Atoi(ipParts[2])
+	if err != nil {
+		panic("Unable to parse BaseIP octet 2")
+	}
+	octet3, err := strconv.Atoi(ipParts[3])
+	if err != nil {
+		panic("Unable to parse BaseIP octet 3")
+	}
+	return []byte{byte(octet0), byte(octet1), byte(octet2), byte(octet3)}
+}
+
+func getConfigurationForService(serviceName string, forwardConfigurationPath string) *ServiceConfiguration {
+	fwdCfg := getForwardConfiguration(forwardConfigurationPath)
+	for _, c := range fwdCfg.ServiceConfigurations {
+		if c.ServiceName == serviceName {
+			return &c
+		}
+	}
+	return nil
+}
+
+func getForwardConfiguration(forwardConfigurationPath string) *ForwardConfiguration {
+	if forwardConfiguration != nil {
+		return forwardConfiguration
+	}
+
+	if forwardConfigurationPath == "" {
+		forwardConfiguration = defaultConfiguration
+		return forwardConfiguration
+	}
+
+	dat, err := os.ReadFile(forwardConfigurationPath)
+	if err != nil {
+		// fall back to existing kubefwd base
+		log.Error(fmt.Sprintf("ForwardConfiguration read error %s", err))
+		forwardConfiguration = defaultConfiguration
+		return forwardConfiguration
+	}
+
+	conf := &ForwardConfiguration{}
+	err = yaml.Unmarshal(dat, conf)
+	if err != nil {
+		// fall back to existing kubefwd base
+		log.Error(fmt.Sprintf("ForwardConfiguration parse error %s", err))
+		forwardConfiguration = defaultConfiguration
+		return forwardConfiguration
+	}
+
+	forwardConfiguration = conf
+	return forwardConfiguration
 }

pkg/fwdnet/fwdnet.go

@@ -13,9 +13,9 @@ import (
 
 // ReadyInterface prepares a local IP address on
 // the loopback interface.
-func ReadyInterface(svcName string, podName string, clusterN int, namespaceN int, port string) (net.IP, error) {
+func ReadyInterface(svcName string, podName string, clusterN int, namespaceN int, port string, forwardConfigurationPath string) (net.IP, error) {
 
-	ip, _ := fwdIp.GetIp(svcName, podName, clusterN, namespaceN)
+	ip, _ := fwdIp.GetIp(svcName, podName, clusterN, namespaceN, forwardConfigurationPath)
 
 	// lo means we are probably on linux and not mac
 	_, err := net.InterfaceByName("lo")

pkg/fwdservice/fwdservice.go

@@ -1,11 +1,11 @@
 package fwdservice
 
 import (
+	"context"
 	"fmt"
 	"strconv"
 	"sync"
 	"time"
-	"context"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/txn2/kubefwd/pkg/fwdnet"
@@ -70,6 +70,8 @@ type ServiceFWD struct {
 	// key = podName
 	PortForwards map[string]*fwdport.PortForwardOpts
 	DoneChannel  chan struct{} // After shutdown is complete, this channel will be closed
+
+	ServiceConfigPath string
 }
 
 /**
@@ -232,7 +234,7 @@ func (svcFwd *ServiceFWD) LoopPodsToForward(pods []v1.Pod, includePodNameInHost
 			svcName = pod.Name + "." + svcFwd.Svc.Name
 		}
 
-		localIp, err := fwdnet.ReadyInterface(svcName, pod.Name, svcFwd.ClusterN, svcFwd.NamespaceN, podPort)
+		localIp, err := fwdnet.ReadyInterface(svcName, pod.Name, svcFwd.ClusterN, svcFwd.NamespaceN, podPort, svcFwd.ServiceConfigPath)
 		if err != nil {
 			log.Warnf("WARNING: error readying interface: %s\n", err)
 		}
@@ -282,10 +284,10 @@ func (svcFwd *ServiceFWD) LoopPodsToForward(pods []v1.Pod, includePodNameInHost
 				svcName,
 			)
 
-			log.Printf("Port-Forward: %s %s:%d to pod %s:%s\n",
+			// 30 chars is a pretty long service name
+			log.Printf("Port-Forward: %-30s %s to pod %s:%s\n",
+				fmt.Sprintf("%s:%d", serviceHostName, port.Port),
 				localIp.String(),
-				serviceHostName,
-				port.Port,
 				pod.Name,
 				podPort,
 			)