Add helper function getHostnameAndSourceIP() (#97)

helpers.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"os"
 	"runtime"
 	"sync"
 	"syscall"
@@ -124,6 +125,31 @@ func getSourceIPAddress(domain string) (net.IP, error) {
 	return srcIP, nil
 }
 
+// getHostnameAndSourceIP returns the hostname and source IP address for the traffic destined to
+// the specified domain.
+func getHostnameAndSourceIP(domain string) (hostname, sourceIP string, err error) {
+	err = runInRootNS(func() error {
+		var joinedErr error
+
+		if name, hostnameErr := os.Hostname(); hostnameErr == nil {
+			hostname = name
+		} else {
+			joinedErr = fmt.Errorf("failed to get hostname: %v", hostnameErr)
+		}
+
+		if srcIP, ipErr := getSourceIPAddress(domain); ipErr == nil {
+			sourceIP = srcIP.String()
+		} else {
+			joinedErr = errors.Join(joinedErr,
+				fmt.Errorf("failed to get source IP: %v", ipErr))
+		}
+
+		return joinedErr
+	})
+
+	return hostname, sourceIP, err
+}
+
 // runInRootNS executes fetcher in the root namespace.
 func runInRootNS(fetcher func() error) error {
 	// We need to call the `setns` syscall to extract information (network route, hostname) from

main.go

@@ -164,25 +164,10 @@ func mainWithExitCode() exitCode {
 	metadataCollector.AddCustomData("os.kernel.release", kernelVersion)
 
 	// hostname and sourceIP will be populated from the root namespace.
-	var hostname, sourceIP string
-
-	if err = runInRootNS(func() error {
-		var hostnameErr error
-		hostname, hostnameErr = os.Hostname()
-		if hostnameErr != nil {
-			return fmt.Errorf("failed to get hostname: %v", hostnameErr)
-		}
-
-		srcIP, ipErr := getSourceIPAddress(args.collAgentAddr)
-		if ipErr != nil {
-			return fmt.Errorf("failed to get source IP: %v", ipErr)
-		}
-		sourceIP = srcIP.String()
-		return nil
-	}); err != nil {
+	hostname, sourceIP, err := getHostnameAndSourceIP(args.collAgentAddr)
+	if err != nil {
 		log.Warnf("Failed to fetch metadata information in the root namespace: %v", err)
 	}
-
 	metadataCollector.AddCustomData("host.name", hostname)
 	metadataCollector.AddCustomData("host.ip", sourceIP)