From 0dc7d081834672fc5548fb87155e0c8f75d755bc Mon Sep 17 00:00:00 2001
From: Tero Saarni <tero.saarni@est.tech>
Date: Fri, 16 Oct 2020 19:11:30 +0300
Subject: [PATCH] Allow user to provide existing CA certificate and key

---
 pkg/certificate/certificate.go | 23 +++++++++++++++++++----
 pkg/certificate/manifest.go    | 11 ++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/pkg/certificate/certificate.go b/pkg/certificate/certificate.go
index 48f0497..bdf20aa 100644
--- a/pkg/certificate/certificate.go
+++ b/pkg/certificate/certificate.go
@@ -52,8 +52,9 @@ type Certificate struct {
 	NotAfter       *time.Time `yaml:"not_after"`
 
 	// generated at runtime, not read from yaml
-	Key  crypto.Signer `yaml:"-"`
-	Cert []byte        `yaml:"-"`
+	Key       crypto.Signer `yaml:"-"`
+	Cert      []byte        `yaml:"-"`
+	Generated bool          `hash:"-"`
 }
 
 // getKeyUsage converts key usage string representation to x509.KeyUsage
@@ -247,6 +248,9 @@ func (c *Certificate) Generate(ca *Certificate) error {
 
 	c.Cert, err = x509.CreateCertificate(rand.Reader, template, issuerCert, c.Key.Public(), issuerKey)
 
+	// Mark the state as valid
+	c.Generated = true
+
 	return err
 }
 
@@ -311,16 +315,27 @@ func (c *Certificate) Load(srcdir string) error {
 		return err
 	}
 	decoded, _ = pem.Decode(buf)
-	if decoded == nil || decoded.Type != "PRIVATE KEY" {
+	if decoded == nil {
+		return fmt.Errorf("Error while decoding %s", keyFilename)
+	}
+
+	var key interface{}
+	if decoded.Type == "PRIVATE KEY" {
+		key, err = x509.ParsePKCS8PrivateKey(decoded.Bytes)
+	} else if decoded.Type == "RSA PRIVATE KEY" {
+		key, err = x509.ParsePKCS1PrivateKey(decoded.Bytes)
+	} else {
 		return fmt.Errorf("Error while decoding %s", keyFilename)
 	}
 
-	key, err := x509.ParsePKCS8PrivateKey(decoded.Bytes)
 	if err != nil {
 		return err
 	}
 	c.Key = key.(crypto.Signer)
 
+	// Mark the state as valid
+	c.Generated = true
+
 	return nil
 }
 
diff --git a/pkg/certificate/manifest.go b/pkg/certificate/manifest.go
index 026bf08..19e54cd 100644
--- a/pkg/certificate/manifest.go
+++ b/pkg/certificate/manifest.go
@@ -67,11 +67,20 @@ func GenerateCertficatesFromManifest(manifestFilename, stateFilename, destinatio
 		allCerts[c.Subject] = &c
 
 		// compare hash from state file to has of loaded certificate
-		if state[c.Subject] == c.Hash() {
+		hash, ok := state[c.Subject]
+		if hash == c.Hash() {
 			fmt.Printf("No changes: skipping %s\n", c.Filename)
 			continue // continue to next certificate in manifest
 		}
 
+		// if certificate is already valid but it did not exist in state file:
+		// "adopt" the existing certificate like we would have generated it
+		if c.Generated && !ok {
+			fmt.Printf("Recognized existing certificate: skipping %s\n", c.Filename)
+			state[c.Subject] = c.Hash()
+			continue // continue to next certificate in manifest
+		}
+
 		ca, ok := allCerts[c.Issuer]
 		if c.Issuer != "" && !ok {
 			return fmt.Errorf("Issuer field defined but CA certificate `%s` not found", c.Issuer)