Add a helper function

monitor/mailutils.go

@@ -12,6 +12,7 @@ package monitor
 import (
 	"crypto/rand"
 	"encoding/hex"
+	"os"
 )
 
 const mailDateFormat = "Mon, 2 Jan 2006 15:04:05 -0700"
@@ -23,3 +24,11 @@ func generateMessageID() string {
 	}
 	return hex.EncodeToString(randomBytes[:]) + "@selfhosted.certspotter.org"
 }
+
+func sendmailPath() string {
+	if envVar := os.Getenv("SENDMAIL_PATH"); envVar != "" {
+		return envVar
+	} else {
+		return "/usr/sbin/sendmail"
+	}
+}

monitor/notify.go

@@ -67,11 +67,6 @@ func sendEmail(ctx context.Context, to []string, notif notification) error {
 	stdin := new(bytes.Buffer)
 	stderr := new(bytes.Buffer)
 
-	sendmailPath := "/usr/sbin/sendmail"
-	if envVar := os.Getenv("SENDMAIL_PATH"); envVar != "" {
-		sendmailPath = envVar
-	}
-
 	fmt.Fprintf(stdin, "To: %s\n", strings.Join(to, ", "))
 	fmt.Fprintf(stdin, "Subject: [certspotter] %s\n", notif.Summary())
 	fmt.Fprintf(stdin, "Date: %s\n", time.Now().Format(mailDateFormat))
@@ -85,7 +80,7 @@ func sendEmail(ctx context.Context, to []string, notif notification) error {
 	args := []string{"-i", "--"}
 	args = append(args, to...)
 
-	sendmail := exec.CommandContext(ctx, sendmailPath, args...)
+	sendmail := exec.CommandContext(ctx, sendmailPath(), args...)
 	sendmail.Stdin = stdin
 	sendmail.Stderr = stderr