add days option

cert.go

@@ -47,7 +47,7 @@ func init() {
 	}
 }
 
-func (m *mkcert) makeCert(hosts []string) {
+func (m *mkcert) makeCert(hosts []string, days int) {
 	if m.caKey == nil {
 		log.Fatalln("ERROR: can't create new certificates because the CA key (rootCA-key.pem) is missing")
 	}
@@ -59,7 +59,7 @@ func (m *mkcert) makeCert(hosts []string) {
 	// Certificates last for 2 years and 3 months, which is always less than
 	// 825 days, the limit that macOS/iOS apply to all certificates,
 	// including custom roots. See https://support.apple.com/en-us/HT210176.
-	expiration := time.Now().AddDate(2, 3, 0)
+	expiration := time.Now().AddDate(0, 0, days)
 
 	tpl := &x509.Certificate{
 		SerialNumber: randomSerialNumber(),

main.go

@@ -54,6 +54,9 @@ const advancedUsage = `Advanced options:
 	-client
 	    Generate a certificate for client authentication.
 
+	-days DAYS
+	    Set the duration that the certificate is valid for. (default: 820 days)
+
 	-ecdsa
 	    Generate a certificate with an ECDSA key.
 
@@ -102,6 +105,7 @@ func main() {
 		certFileFlag  = flag.String("cert-file", "", "")
 		keyFileFlag   = flag.String("key-file", "", "")
 		p12FileFlag   = flag.String("p12-file", "", "")
+		daysFlag      = flag.Int("days", 820, "")
 		versionFlag   = flag.Bool("version", false, "")
 	)
 	flag.Usage = func() {
@@ -146,7 +150,7 @@ func main() {
 		installMode: *installFlag, uninstallMode: *uninstallFlag, csrPath: *csrFlag,
 		pkcs12: *pkcs12Flag, ecdsa: *ecdsaFlag, client: *clientFlag,
 		certFile: *certFileFlag, keyFile: *keyFileFlag, p12File: *p12FileFlag,
-	}).Run(flag.Args())
+	}).Run(flag.Args(), *daysFlag)
 }
 
 const rootName = "rootCA.pem"
@@ -168,7 +172,7 @@ type mkcert struct {
 	ignoreCheckFailure bool
 }
 
-func (m *mkcert) Run(args []string) {
+func (m *mkcert) Run(args []string, days int) {
 	m.CAROOT = getCAROOT()
 	if m.CAROOT == "" {
 		log.Fatalln("ERROR: failed to find the default CA location, set one as the CAROOT env var")
@@ -234,7 +238,7 @@ func (m *mkcert) Run(args []string) {
 		}
 	}
 
-	m.makeCert(args)
+	m.makeCert(args, days)
 }
 
 func getCAROOT() string {