feat(spanner): mTLS setup for spanner external host clients

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java

@@ -71,9 +71,13 @@
 import io.grpc.ExperimentalApi;
 import io.grpc.ManagedChannelBuilder;
 import io.grpc.MethodDescriptor;
+import io.grpc.netty.shaded.io.grpc.netty.GrpcSslContexts;
+import io.grpc.netty.shaded.io.grpc.netty.NettyChannelBuilder;
+import io.grpc.netty.shaded.io.netty.handler.ssl.SslContext;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.api.OpenTelemetry;
 import io.opentelemetry.api.common.Attributes;
+import java.io.File;
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -952,6 +956,7 @@ public static class Builder
     private boolean enableEndToEndTracing = SpannerOptions.environment.isEnableEndToEndTracing();
     private boolean enableBuiltInMetrics = SpannerOptions.environment.isEnableBuiltInMetrics();
     private String monitoringHost = SpannerOptions.environment.getMonitoringHost();
+    private SslContext mTLSContext = null;
 
     private static String createCustomClientLibToken(String token) {
       return token + " " + ServiceOptions.getGoogApiClientLibName();
@@ -1485,6 +1490,27 @@ public Builder setEmulatorHost(String emulatorHost) {
       return this;
     }
 
+    /**
+     * Configures mTLS authentication using the provided client certificate and key files. mTLS is
+     * only supported for external spanner hosts.
+     *
+     * @param clientCertificate Path to the client certificate file.
+     * @param clientCertificateKey Path to the client private key file.
+     * @throws SpannerException If an error occurs while configuring the mTLS context
+     */
+    @ExperimentalApi("https://github.com/googleapis/java-spanner/pull/3574")
+    public Builder useClientCert(String clientCertificate, String clientCertificateKey) {
+      try {
+        this.mTLSContext =
+            GrpcSslContexts.forClient()
+                .keyManager(new File(clientCertificate), new File(clientCertificateKey))
+                .build();
+      } catch (Exception e) {
+        throw SpannerExceptionFactory.asSpannerException(e);
+      }
+      return this;
+    }
+
     /**
      * Sets OpenTelemetry object to be used for Spanner Metrics and Traces. GlobalOpenTelemetry will
      * be used as fallback if this options is not set.
@@ -1594,6 +1620,15 @@ public SpannerOptions build() {
         // As we are using plain text, we should never send any credentials.
         this.setCredentials(NoCredentials.getInstance());
       }
+      if (mTLSContext != null) {
+        this.setChannelConfigurator(
+            builder -> {
+              if (builder instanceof NettyChannelBuilder) {
+                ((NettyChannelBuilder) builder).sslContext(mTLSContext);
+              }
+              return builder;
+            });
+      }
       if (this.numChannels == null) {
         this.numChannels =
             this.grpcGcpExtensionEnabled ? GRPC_GCP_ENABLED_DEFAULT_CHANNELS : DEFAULT_CHANNELS;

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionOptions.java

@@ -20,6 +20,8 @@
 import static com.google.cloud.spanner.connection.ConnectionProperties.AUTO_CONFIG_EMULATOR;
 import static com.google.cloud.spanner.connection.ConnectionProperties.AUTO_PARTITION_MODE;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CHANNEL_PROVIDER;
+import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_CERTIFICATE;
+import static com.google.cloud.spanner.connection.ConnectionProperties.CLIENT_KEY;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CREDENTIALS_PROVIDER;
 import static com.google.cloud.spanner.connection.ConnectionProperties.CREDENTIALS_URL;
 import static com.google.cloud.spanner.connection.ConnectionProperties.DATABASE_ROLE;
@@ -225,6 +227,8 @@ public String[] getValidValues() {
   static final boolean DEFAULT_USE_VIRTUAL_THREADS = false;
   static final boolean DEFAULT_USE_VIRTUAL_GRPC_TRANSPORT_THREADS = false;
   static final String DEFAULT_CREDENTIALS = null;
+  static final String DEFAULT_CLIENT_CERTIFICATE = null;
+  static final String DEFAULT_CLIENT_KEY = null;
   static final String DEFAULT_OAUTH_TOKEN = null;
   static final Integer DEFAULT_MIN_SESSIONS = null;
   static final Integer DEFAULT_MAX_SESSIONS = null;
@@ -263,6 +267,10 @@ public String[] getValidValues() {
   private static final String DEFAULT_EMULATOR_HOST = "http://localhost:9010";
   /** Use plain text is only for local testing purposes. */
   static final String USE_PLAIN_TEXT_PROPERTY_NAME = "usePlainText";
+  /** Client certificate path to establish mTLS */
+  static final String CLIENT_CERTIFICATE_PROPERTY_NAME = "clientCertificate";
+  /** Client key path to establish mTLS */
+  static final String CLIENT_KEY_PROPERTY_NAME = "clientKey";
   /** Name of the 'autocommit' connection property. */
   public static final String AUTOCOMMIT_PROPERTY_NAME = "autocommit";
   /** Name of the 'readonly' connection property. */
@@ -434,6 +442,12 @@ static boolean isEnableTransactionalConnectionStateForPostgreSQL() {
                       USE_PLAIN_TEXT_PROPERTY_NAME,
                       "Use a plain text communication channel (i.e. non-TLS) for communicating with the server (true/false). Set this value to true for communication with the Cloud Spanner emulator.",
                       DEFAULT_USE_PLAIN_TEXT),
+                  ConnectionProperty.createStringProperty(
+                      CLIENT_CERTIFICATE_PROPERTY_NAME,
+                      "Specifies the file path to the client certificate required for establishing an mTLS connection."),
+                  ConnectionProperty.createStringProperty(
+                      CLIENT_KEY_PROPERTY_NAME,
+                      "Specifies the file path to the client private key required for establishing an mTLS connection."),
                   ConnectionProperty.createStringProperty(
                       USER_AGENT_PROPERTY_NAME,
                       "The custom user-agent property name to use when communicating with Cloud Spanner. This property is intended for internal library usage, and should not be set by applications."),
@@ -1291,6 +1305,14 @@ boolean isUsePlainText() {
         || getInitialConnectionPropertyValue(USE_PLAIN_TEXT);
   }
 
+  String getClientCertificate() {
+    return getInitialConnectionPropertyValue(CLIENT_CERTIFICATE);
+  }
+
+  String getClientCertificateKey() {
+    return getInitialConnectionPropertyValue(CLIENT_KEY);
+  }
+
   /**
    * The (custom) user agent string to use for this connection. If <code>null</code>, then the
    * default JDBC user agent string will be used.

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ConnectionProperties.java

@@ -22,6 +22,8 @@
 import static com.google.cloud.spanner.connection.ConnectionOptions.AUTO_BATCH_DML_UPDATE_COUNT_VERIFICATION_PROPERTY_NAME;
 import static com.google.cloud.spanner.connection.ConnectionOptions.AUTO_PARTITION_MODE_PROPERTY_NAME;
 import static com.google.cloud.spanner.connection.ConnectionOptions.CHANNEL_PROVIDER_PROPERTY_NAME;
+import static com.google.cloud.spanner.connection.ConnectionOptions.CLIENT_CERTIFICATE_PROPERTY_NAME;
+import static com.google.cloud.spanner.connection.ConnectionOptions.CLIENT_KEY_PROPERTY_NAME;
 import static com.google.cloud.spanner.connection.ConnectionOptions.CREDENTIALS_PROPERTY_NAME;
 import static com.google.cloud.spanner.connection.ConnectionOptions.CREDENTIALS_PROVIDER_PROPERTY_NAME;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DATABASE_ROLE_PROPERTY_NAME;
@@ -33,6 +35,8 @@
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_AUTO_BATCH_DML_UPDATE_COUNT_VERIFICATION;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_AUTO_PARTITION_MODE;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_CHANNEL_PROVIDER;
+import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_CLIENT_CERTIFICATE;
+import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_CLIENT_KEY;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_CREDENTIALS;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_DATABASE_ROLE;
 import static com.google.cloud.spanner.connection.ConnectionOptions.DEFAULT_DATA_BOOST_ENABLED;
@@ -192,6 +196,20 @@ public class ConnectionProperties {
           BooleanConverter.INSTANCE,
           Context.STARTUP);
 
+  static final ConnectionProperty<String> CLIENT_CERTIFICATE =
+      create(
+          CLIENT_CERTIFICATE_PROPERTY_NAME,
+          "Specifies the file path to the client certificate required for establishing an mTLS connection.",
+          DEFAULT_CLIENT_CERTIFICATE,
+          StringValueConverter.INSTANCE,
+          Context.STARTUP);
+  static final ConnectionProperty<String> CLIENT_KEY =
+      create(
+          CLIENT_KEY_PROPERTY_NAME,
+          "Specifies the file path to the client private key required for establishing an mTLS connection.",
+          DEFAULT_CLIENT_KEY,
+          StringValueConverter.INSTANCE,
+          Context.STARTUP);
   static final ConnectionProperty<String> CREDENTIALS_URL =
       create(
           CREDENTIALS_PROPERTY_NAME,

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/SpannerPool.java

@@ -161,6 +161,8 @@ static class SpannerPoolKey {
     private final Boolean enableExtendedTracing;
     private final Boolean enableApiTracing;
     private final boolean enableEndToEndTracing;
+    private final String clientCertificate;
+    private final String clientCertificateKey;
 
     @VisibleForTesting
     static SpannerPoolKey of(ConnectionOptions options) {
@@ -192,6 +194,8 @@ private SpannerPoolKey(ConnectionOptions options) throws IOException {
       this.enableExtendedTracing = options.isEnableExtendedTracing();
       this.enableApiTracing = options.isEnableApiTracing();
       this.enableEndToEndTracing = options.isEndToEndTracingEnabled();
+      this.clientCertificate = options.getClientCertificate();
+      this.clientCertificateKey = options.getClientCertificateKey();
     }
 
     @Override
@@ -214,7 +218,9 @@ public boolean equals(Object o) {
           && Objects.equals(this.openTelemetry, other.openTelemetry)
           && Objects.equals(this.enableExtendedTracing, other.enableExtendedTracing)
           && Objects.equals(this.enableApiTracing, other.enableApiTracing)
-          && Objects.equals(this.enableEndToEndTracing, other.enableEndToEndTracing);
+          && Objects.equals(this.enableEndToEndTracing, other.enableEndToEndTracing)
+          && Objects.equals(this.clientCertificate, other.clientCertificate)
+          && Objects.equals(this.clientCertificateKey, other.clientCertificateKey);
     }
 
     @Override
@@ -233,7 +239,9 @@ public int hashCode() {
           this.openTelemetry,
           this.enableExtendedTracing,
           this.enableApiTracing,
-          this.enableEndToEndTracing);
+          this.enableEndToEndTracing,
+          this.clientCertificate,
+          this.clientCertificateKey);
     }
   }
 
@@ -393,6 +401,9 @@ Spanner createSpanner(SpannerPoolKey key, ConnectionOptions options) {
       // Set a custom channel configurator to allow http instead of https.
       builder.setChannelConfigurator(ManagedChannelBuilder::usePlaintext);
     }
+    if (key.clientCertificate != null && key.clientCertificateKey != null) {
+      builder.useClientCert(key.clientCertificate, key.clientCertificateKey);
+    }
     if (options.getConfigurator() != null) {
       options.getConfigurator().configure(builder);
     }