add cli option to update ip based on the dyndns

cli/main.go

@@ -178,7 +178,7 @@ func run() error {
 		currIP, newIP := publicDNSIps[0], dynamicDNSIps[0]
 		if currIP.Equal(newIP) {
 			glog.Infof("IPs of dyndns and current ip match, nothing to do: current=%s, dyndns=%s", currIP, newIP)
-			// return nil // TODO: uncomment
+			return nil
 		}
 		// setup git repo
 		gitFs, err := NewGitFS(repository)

cli/update_viktorbarzin_me.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"net"
 	"os"
+	"strings"
 
 	"github.com/pkg/errors"
 )
@@ -13,20 +15,61 @@ const (
 	publicDomainFlagName          = "public-domain"
 	updatePublicIPUseCaseFlagName = "kek"
 
-	tfvarsFileRelative = "/terraform.tfvars"
+	maintfFileRelative = "/main.tf"
 )
 
 func updatePublicIP(gitFs *GitFS, currIp, newIp net.IP) error {
-	println(currIp.String())
+	/* Steps to update:
-	println(newIp.String())
+	1. Read main.tf where we update the bind config with the public ip (replace all occurrences of the public ip)
+		1.1) read the line where the variable is specified i.e
+			bind_db_viktorbarzin_me  = replace(var.bind_db_viktorbarzin_me, "<current_ip>", "<new_ip>")
+		1.2) switch <new_ip> and <currenct_ip>
+		1.3) replace second ip (<new_ip> or after the switch <current_ip>) with the new_ip
+	2. Update godaddy glue record
 
-	f, err := (*gitFs.fs).OpenFile(tfvarsFileRelative, os.O_RDONLY, 0644)
+	*/
+	newMainTfContents, err := getNewContent(gitFs, currIp, newIp)
+	if err != nil {
+		return errors.Wrapf(err, "failed to get updated main.tf contents")
+	}
+	f, err := (*gitFs.fs).OpenFile(maintfFileRelative, os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		return errors.Wrapf(err, "failed to open file %s for writing", maintfFileRelative)
+	}
+	if _, err = f.Write([]byte(newMainTfContents)); err != nil {
+		return errors.Wrapf(err, "failed to write back new contents to %s:\n %s", maintfFileRelative, newMainTfContents)
+	}
+	return nil
+}
+
+// Get updated contents of main.tf
+func getNewContent(gitFs *GitFS, currIp, newIp net.IP) (string, error) {
+	f, err := (*gitFs.fs).OpenFile(maintfFileRelative, os.O_RDONLY, 0644)
 	defer f.Close()
 	if err != nil {
-		return errors.Wrapf(err, "failed to open tfvars file: %s", tfvarsFileRelative)
+		return "", errors.Wrapf(err, "failed to open tfvars file: %s", maintfFileRelative)
 	}
 	bytes, err := ioutil.ReadAll(f)
-	println(string(bytes))
+	contents := string(bytes)
 
-	return errors.New("test")
+	newLines := []string{}
+	for _, line := range strings.Split(contents, "\n") {
+		lineToAdd := line
+		// if line is the one that sets un the bind config
+		if strings.HasPrefix(line, "  bind_db_viktorbarzin_me") {
+			// extract old and new ip
+			// line example:
+			//  bind_db_viktorbarzin_me  = replace(var.bind_db_viktorbarzin_me, "<current_ip>", "<new_ip>")
+			lineToAdd = strings.Replace(lineToAdd, "\"", "", -1) // remove all quotes
+			lineToAdd = strings.Replace(lineToAdd, ")", "", -1)  // remove the trailing closing bracket
+			splitByComma := strings.Split(lineToAdd, ",")
+			if len(splitByComma) != 3 {
+				return "", fmt.Errorf("invalid line; got: %s", line)
+			}
+			newIpStr := strings.ReplaceAll(splitByComma[2], " ", "")
+			lineToAdd = fmt.Sprintf("  bind_db_viktorbarzin_me  = replace(var.bind_db_viktorbarzin_me, \"%s\", \"%s\")", newIpStr, newIp.String())
+		}
+		newLines = append(newLines, lineToAdd)
+	}
+	return strings.Join(newLines, "\n"), nil
 }