txeh command line utility

README.md

@@ -1,15 +1,35 @@
 ![txeh - /etc/hosts mangement](txeh.png)
 
 
-# Etc Hosts Management Library
+# Etc Hosts Management Utility & Go Library
 
 [![Go Report Card](https://goreportcard.com/badge/github.com/txn2/txeh)](https://goreportcard.com/report/github.com/txn2/txeh)
 [![GoDoc](https://godoc.org/github.com/txn2/irsync/txeh?status.svg)](https://godoc.org/github.com/txn2/txeh)
 
+## txeh Utility
 
+The txeh CLI application allows command line or scripted access to /etc/hosts file modification.
+
+Examples:
+```bash
+# point the hostnames "test" and "test.two" to local loopback
+sudo txeh add 127.0.0.1 test test.two
+
+# remove the hostname "test"
+sudo txeh remove test
+```
+
+
+
+
+### Motivation
+
+TXEH was build to support [kubefwd](https://github.com/txn2/kubefwd), a Kubernetes port-forwarding utility utilizing [/etc/hosts] to associate custom hostnames with local IP addresses. A computer's [/etc/hosts] file is a powerful utility for developers and system administrators to create localized, custom DNS entries.
 
 This small go library was developed to encapsulate the complexity of
-working with /etc/hosts by providing a simple interface to load, create, remove and save entries to an /etc/host file. No validation is done on the input data. Validation is considered out of scope for this project, use with caution.
+working with /etc/hosts by providing a simple interface to load, create, remove and save entries to an /etc/host file. No validation is done on the input data. **Validation is considered out of scope for this project, use with caution**.
+
+
 
 Basic implemention:
 ```go
@@ -55,3 +75,5 @@ func main() {
 }
 
 ```
+
+[/etc/hosts]:https://en.wikipedia.org/wiki/Hosts_(file)

util/cmd/add.go

@@ -0,0 +1,58 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(addCmd)
+}
+
+var addCmd = &cobra.Command{
+	Use:   "add [IP] [HOSTNAME] [HOSTNAME] [HOSTNAME]...",
+	Short: "Add hostnames to /etc/hosts",
+	Long:  `Add/Associate one or more hostnames to an IP address `,
+	Args: func(cmd *cobra.Command, args []string) error {
+		if len(args) < 2 {
+			return errors.New("the \"add\" command requires an IP address and at least one hostname")
+		}
+
+		if validateIPAddress(args[0]) == false {
+			return errors.New("the IP address provided is not a valid ipv4 or ipv6 address")
+		}
+
+		if ok, hn := validateHostnames(args[1:]); !ok {
+			return errors.New(fmt.Sprintf("\"%s\" is not a valid hostname", hn))
+		}
+
+		return nil
+	},
+	Run: func(cmd *cobra.Command, args []string) {
+		if !Quiet {
+			fmt.Printf("Adding host(s) \"%s\" to IP address %s\n", strings.Join(args[1:], " "), args[0])
+		}
+
+		AddHosts(args[0], args[1:])
+	},
+}
+
+func AddHosts(ip string, hosts []string) {
+
+	etcHosts.AddHosts(ip, hosts)
+
+	if DryRun {
+		fmt.Print(etcHosts.RenderHostsFile())
+		return
+	}
+
+	err := etcHosts.Save()
+	if err != nil {
+		fmt.Printf("Error: could not save %s. Reason: %s\n", etcHosts.WriteFilePath, err.Error())
+		os.Exit(1)
+	}
+}

util/cmd/remove.go

@@ -0,0 +1,28 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(removeCmd)
+}
+
+var removeCmd = &cobra.Command{
+	Use:   "remove [TYPE] [HOSTNAME|IP] [HOSTNAME|IP] [HOSTNAME|IP]...",
+	Short: "Remove a hostname or ip address",
+	Long:  `Remove one or more hostnames or ip addresses from /etc/hosts`,
+	Run: func(cmd *cobra.Command, args []string) {
+		err := cmd.Help()
+		if err != nil {
+			fmt.Printf("Error: can not display help, reason: %s\n", err.Error())
+			os.Exit(1)
+		}
+
+		fmt.Println("Please specify a sub-command such as \"host\" or \"ip\"")
+		os.Exit(1)
+	},
+}

util/cmd/remove_host.go

@@ -0,0 +1,54 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	removeCmd.AddCommand(removeHostCmd)
+}
+
+var removeHostCmd = &cobra.Command{
+	Use:   "host [HOSTNAME] [HOSTNAME] [HOSTNAME]...",
+	Short: "Remove hostnames from /etc/hosts",
+	Long:  `Remove one or more hostnames from /etc/hosts`,
+	Args: func(cmd *cobra.Command, args []string) error {
+		if len(args) < 1 {
+			return errors.New("the \"remove hosts\" command requires at least one hostname to remove")
+		}
+
+		if ok, hn := validateHostnames(args); !ok {
+			return errors.New(fmt.Sprintf("\"%s\" is not a valid hostname", hn))
+		}
+
+		return nil
+	},
+	Run: func(cmd *cobra.Command, args []string) {
+		if !Quiet {
+			fmt.Printf("Removing host(s) \"%s\"\n", strings.Join(args, " "))
+		}
+
+		RemoveHosts(args)
+	},
+}
+
+func RemoveHosts(hosts []string) {
+
+	etcHosts.RemoveHosts(hosts)
+
+	if DryRun {
+		fmt.Print(etcHosts.RenderHostsFile())
+		return
+	}
+
+	err := etcHosts.Save()
+	if err != nil {
+		fmt.Printf("Error: could not save %s. Reason: %s\n", etcHosts.WriteFilePath, err.Error())
+		os.Exit(1)
+	}
+}

util/cmd/remove_ip.go

@@ -0,0 +1,54 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	removeCmd.AddCommand(removeIpCmd)
+}
+
+var removeIpCmd = &cobra.Command{
+	Use:   "ip [IP] [IP] [IP]...",
+	Short: "Remove IP addresses from /etc/hosts",
+	Long:  `Remove one or more IP addresses from /etc/hosts`,
+	Args: func(cmd *cobra.Command, args []string) error {
+		if len(args) < 1 {
+			return errors.New("the \"remove ip\" command requires at least one IP address to remove")
+		}
+
+		if ok, ip := validateIPAddresses(args); !ok {
+			return errors.New(fmt.Sprintf("\"%s\" is not a valid ip address", ip))
+		}
+
+		return nil
+	},
+	Run: func(cmd *cobra.Command, args []string) {
+		if !Quiet {
+			fmt.Printf("Removing ip(s) \"%s\"\n", strings.Join(args, " "))
+		}
+
+		RemoveIPs(args)
+	},
+}
+
+func RemoveIPs(ips []string) {
+
+	etcHosts.RemoveAddresses(ips)
+
+	if DryRun {
+		fmt.Print(etcHosts.RenderHostsFile())
+		return
+	}
+
+	err := etcHosts.Save()
+	if err != nil {
+		fmt.Printf("Error: could not save %s. Reason: %s\n", etcHosts.WriteFilePath, err.Error())
+		os.Exit(1)
+	}
+}

util/cmd/root.go

@@ -0,0 +1,120 @@
+package cmd
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"regexp"
+
+	"github.com/spf13/cobra"
+	"github.com/txn2/txeh"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "txeh",
+	Short: "txeh is a /etc/hosts manager",
+	Long: ` _            _
+| |___  _____| |__
+| __\ \/ / _ \ '_ \
+| |_ >  <  __/ | | |
+ \__/_/\_\___|_| |_| v` + VERSION + `
+
+Add, remove and re-associate hostname entries in your /etc/hosts file.
+Read more including useage as a Go library at https://github.com/txn2/txeh`,
+	Run: func(cmd *cobra.Command, args []string) {
+		err := cmd.Help()
+		if err != nil {
+			fmt.Printf("Error: can not display help, reason: %s\n", err.Error())
+			os.Exit(1)
+		}
+
+		fmt.Println("Please specify a sub-command such as \"add\" or \"remove\"")
+		os.Exit(1)
+	},
+	PersistentPreRun: func(cmd *cobra.Command, args []string) {
+		initEtcHosts()
+	},
+}
+
+var Quiet bool
+var HostsFileReadPath string
+var HostsFileWritePath string
+var DryRun bool
+
+var etcHosts *txeh.Hosts
+var hostnameRegex *regexp.Regexp
+
+func init() {
+	rootCmd.PersistentFlags().BoolVarP(&DryRun, "dryrun", "d", false, "dry run, output to stdout (ignores quiet)")
+	rootCmd.PersistentFlags().BoolVarP(&Quiet, "quiet", "q", false, "no output")
+	rootCmd.PersistentFlags().StringVarP(&HostsFileReadPath, "read", "r", "", "(override) Path to read /etc/hosts file.")
+	rootCmd.PersistentFlags().StringVarP(&HostsFileWritePath, "write", "w", "", "(override) Path to write /etc/hosts file.")
+
+	// validate hostnames (allow underscore for service records)
+	hostnameRegex = regexp.MustCompile(`^([A-Za-z]|[0-9]|-|_|\.)+$`)
+}
+
+func validateIPAddresses(ips []string) (bool, string) {
+	for _, ip := range ips {
+		if validateIPAddress(ip) == false {
+			return false, ip
+		}
+	}
+
+	return true, ""
+}
+
+func validateIPAddress(ip string) bool {
+
+	if net.ParseIP(ip) == nil {
+		return false
+	}
+
+	return true
+}
+
+func validateHostnames(hostnames []string) (bool, string) {
+	for _, hn := range hostnames {
+		if validateHostname(hn) != true {
+			return false, hn
+		}
+	}
+
+	return true, ""
+}
+
+func validateHostname(hostname string) bool {
+	return hostnameRegex.MatchString(hostname)
+}
+
+func initEtcHosts() {
+	if HostsFileReadPath == "" && HostsFileWritePath == "" {
+		hosts, err := txeh.NewHostsDefault()
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+
+		etcHosts = hosts
+		return
+	}
+
+	hosts, err := txeh.NewHosts(&txeh.HostsConfig{
+		ReadFilePath:  HostsFileReadPath,
+		WriteFilePath: HostsFileWritePath,
+	})
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	etcHosts = hosts
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	return
+}

util/cmd/version.go

@@ -0,0 +1,22 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+const VERSION = "0.0.0"
+
+func init() {
+	rootCmd.AddCommand(versionCmd)
+}
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Print the version number of txeh",
+	Long:  ``,
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("txeh Version %s", VERSION)
+	},
+}

util/txeh.go

@@ -0,0 +1,7 @@
+package main
+
+import "github.com/txn2/txeh/util/cmd"
+
+func main() {
+	cmd.Execute()
+}