Merge pull request #17 from kpumuk/custom-tls

Added option to use custom TLS certificates instead of ACME

README.md

@@ -89,6 +89,15 @@ applications. To enable this, add the `--tls` flag when deploying an instance:
     kamal-proxy deploy service1 --target web-1:3000 --host app1.example.com --tls
 
 
+### Custom TLS certificate
+
+When you obtained your TLS certificate manually, manage your own certificate authority,
+or need to install Cloudflare origin certificate, you can manually specify path to
+your certificate file and the corresponding private key:
+
+    kamal-proxy deploy service1 --target web-1:3000 --host app1.example.com --tls --tls-certificate-path cert.pem --tls-private-key-path key.pem
+
+
 ## Specifying `run` options with environment variables
 
 In some environments, like when running a Docker container, it can be convenient

internal/cmd/deploy.go

@@ -31,6 +31,8 @@ func newDeployCommand() *deployCommand {
 
 	deployCommand.cmd.Flags().BoolVar(&deployCommand.args.ServiceOptions.TLSEnabled, "tls", false, "Configure TLS for this target (requires a non-empty host)")
 	deployCommand.cmd.Flags().BoolVar(&deployCommand.tlsStaging, "tls-staging", false, "Use Let's Encrypt staging environment for certificate provisioning")
+	deployCommand.cmd.Flags().StringVar(&deployCommand.args.ServiceOptions.TLSCertificatePath, "tls-certificate-path", "", "Configure custom TLS certificate path (PEM format)")
+	deployCommand.cmd.Flags().StringVar(&deployCommand.args.ServiceOptions.TLSPrivateKeyPath, "tls-private-key-path", "", "Configure custom TLS private key path (PEM format)")
 
 	deployCommand.cmd.Flags().DurationVar(&deployCommand.args.DeployTimeout, "deploy-timeout", server.DefaultDeployTimeout, "Maximum time to wait for the new target to become healthy")
 	deployCommand.cmd.Flags().DurationVar(&deployCommand.args.DrainTimeout, "drain-timeout", server.DefaultDrainTimeout, "Maximum time to allow existing connections to drain before removing old target")
@@ -53,6 +55,7 @@ func newDeployCommand() *deployCommand {
 	deployCommand.cmd.Flags().BoolVar(&deployCommand.args.TargetOptions.ForwardHeaders, "forward-headers", false, "Forward X-Forwarded headers to target (default false if TLS enabled; otherwise true)")
 
 	deployCommand.cmd.MarkFlagRequired("target")
+	deployCommand.cmd.MarkFlagsRequiredTogether("tls-certificate-path", "tls-private-key-path")
 
 	return deployCommand
 }

internal/server/cert.go

@@ -0,0 +1,61 @@
+package server
+
+import (
+	"crypto/tls"
+	"log/slog"
+	"net/http"
+	"sync"
+)
+
+type CertManager interface {
+	GetCertificate(hello *tls.ClientHelloInfo) (*tls.Certificate, error)
+	HTTPHandler(handler http.Handler) http.Handler
+}
+
+// StaticCertManager is a certificate manager that loads certificates from disk.
+type StaticCertManager struct {
+	tlsCertificateFilePath string
+	tlsPrivateKeyFilePath  string
+	cert                   *tls.Certificate
+	lock                   sync.RWMutex
+}
+
+func NewStaticCertManager(tlsCertificateFilePath, tlsPrivateKeyFilePath string) *StaticCertManager {
+	return &StaticCertManager{
+		tlsCertificateFilePath: tlsCertificateFilePath,
+		tlsPrivateKeyFilePath:  tlsPrivateKeyFilePath,
+	}
+}
+
+func (m *StaticCertManager) GetCertificate(*tls.ClientHelloInfo) (*tls.Certificate, error) {
+	m.lock.RLock()
+	if m.cert != nil {
+		defer m.lock.RUnlock()
+		return m.cert, nil
+	}
+	m.lock.RUnlock()
+
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	if m.cert != nil { // Double-check locking
+		return m.cert, nil
+	}
+
+	slog.Info(
+		"Loading custom TLS certificate",
+		"tls-certificate-path", m.tlsCertificateFilePath,
+		"tls-private-key-path", m.tlsPrivateKeyFilePath,
+	)
+
+	cert, err := tls.LoadX509KeyPair(m.tlsCertificateFilePath, m.tlsPrivateKeyFilePath)
+	if err != nil {
+		return nil, err
+	}
+	m.cert = &cert
+
+	return m.cert, nil
+}
+
+func (m *StaticCertManager) HTTPHandler(handler http.Handler) http.Handler {
+	return handler
+}

internal/server/cert_test.go

@@ -0,0 +1,105 @@
+package server
+
+import (
+	"crypto/tls"
+	"os"
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+const certPem = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`
+
+const keyPem = `-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIIrYSSNQFaA2Hwf1duRSxKtLYX5CB04fSeQ6tF1aY/PuoAoGCCqGSM49
+AwEHoUQDQgAEPR3tU2Fta9ktY+6P9G0cWO+0kETA6SFs38GecTyudlHz6xvCdz8q
+EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
+-----END EC PRIVATE KEY-----`
+
+func TestCertificateLoading(t *testing.T) {
+	certPath, keyPath, err := prepareTestCertificateFiles(t)
+	require.NoError(t, err)
+
+	manager := NewStaticCertManager(certPath, keyPath)
+	cert, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.NoError(t, err)
+	require.NotNil(t, cert)
+}
+
+func TestCertificateLoadingRaceCondition(t *testing.T) {
+	certPath, keyPath, err := prepareTestCertificateFiles(t)
+	require.NoError(t, err)
+
+	manager := NewStaticCertManager(certPath, keyPath)
+	go func() {
+		_, err2 := manager.GetCertificate(&tls.ClientHelloInfo{})
+		require.NoError(t, err2)
+	}()
+	cert, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.NoError(t, err)
+	require.NotNil(t, cert)
+}
+
+func TestCachesLoadedCertificate(t *testing.T) {
+	certPath, keyPath, err := prepareTestCertificateFiles(t)
+	require.NoError(t, err)
+
+	manager := NewStaticCertManager(certPath, keyPath)
+	cert1, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.NoError(t, err)
+	require.NotNil(t, cert1)
+
+	require.Nil(t, os.Remove(certPath))
+	require.Nil(t, os.Remove(keyPath))
+
+	cert2, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.Equal(t, cert1, cert2)
+}
+
+func TestErrorWhenFileDoesNotExist(t *testing.T) {
+	manager := NewStaticCertManager("testdata/cert.pem", "testdata/key.pem")
+	cert1, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.ErrorContains(t, err, "no such file or directory")
+	require.Nil(t, cert1)
+}
+
+func TestErrorWhenKeyFormatIsInvalid(t *testing.T) {
+	certPath, keyPath, err := prepareTestCertificateFiles(t)
+	require.NoError(t, err)
+
+	manager := NewStaticCertManager(keyPath, certPath)
+	cert1, err := manager.GetCertificate(&tls.ClientHelloInfo{})
+	require.ErrorContains(t, err, "failed to find certificate PEM data in certificate input")
+	require.Nil(t, cert1)
+}
+
+func prepareTestCertificateFiles(t *testing.T) (string, string, error) {
+	t.Helper()
+
+	dir := t.TempDir()
+	certFile := path.Join(dir, "example-cert.pem")
+	keyFile := path.Join(dir, "example-key.pem")
+
+	err := os.WriteFile(certFile, []byte(certPem), 0644)
+	if err != nil {
+		return "", "", err
+	}
+
+	err = os.WriteFile(keyFile, []byte(keyPem), 0644)
+	if err != nil {
+		return "", "", err
+	}
+
+	return certFile, keyFile, nil
+}

internal/server/service.go

@@ -60,10 +60,12 @@ type HealthCheckConfig struct {
 }
 
 type ServiceOptions struct {
-	TLSEnabled    bool   `json:"tls_enabled"`
-	ACMEDirectory string `json:"acme_directory"`
-	ACMECachePath string `json:"acme_cache_path"`
-	ErrorPagePath string `json:"error_page_path"`
+	TLSEnabled         bool   `json:"tls_enabled"`
+	TLSCertificatePath string `json:"tls_certificate_path"`
+	TLSPrivateKeyPath  string `json:"tls_private_key_path"`
+	ACMEDirectory      string `json:"acme_directory"`
+	ACMECachePath      string `json:"acme_cache_path"`
+	ErrorPagePath      string `json:"error_page_path"`
 }
 
 func (so ServiceOptions) ScopedCachePath() string {
@@ -90,7 +92,7 @@ type Service struct {
 
 	pauseController   *PauseController
 	rolloutController *RolloutController
-	certManager       *autocert.Manager
+	certManager       CertManager
 	middleware        http.Handler
 }
 
@@ -284,11 +286,15 @@ func (s *Service) initialize() {
 	s.middleware = s.createMiddleware()
 }
 
-func (s *Service) createCertManager() *autocert.Manager {
+func (s *Service) createCertManager() CertManager {
 	if !s.options.TLSEnabled {
 		return nil
 	}
 
+	if s.options.TLSCertificatePath != "" && s.options.TLSPrivateKeyPath != "" {
+		return NewStaticCertManager(s.options.TLSCertificatePath, s.options.TLSPrivateKeyPath)
+	}
+
 	return &autocert.Manager{
 		Prompt:     autocert.AcceptTOS,
 		Cache:      autocert.DirCache(s.options.ScopedCachePath()),

internal/server/service_test.go

@@ -42,6 +42,21 @@ func TestService_RedirectToHTTPWhenTLSRequired(t *testing.T) {
 	require.Equal(t, http.StatusOK, w.Result().StatusCode)
 }
 
+func TestService_UseStaticTLSCertificateWhenConfigured(t *testing.T) {
+	service := testCreateService(
+		t,
+		[]string{"example.com"},
+		ServiceOptions{
+			TLSEnabled:         true,
+			TLSCertificatePath: "cert.pem",
+			TLSPrivateKeyPath:  "key.pem",
+		},
+		defaultTargetOptions,
+	)
+
+	require.IsType(t, &StaticCertManager{}, service.certManager)
+}
+
 func TestService_RejectTLSRequestsWhenNotConfigured(t *testing.T) {
 	service := testCreateService(t, defaultEmptyHosts, defaultServiceOptions, defaultTargetOptions)