@@ -35,6 +35,7 @@
 import com.google.api.gax.rpc.ApiCallContext;
 import com.google.api.gax.rpc.ApiClientHeaderProvider;
 import com.google.api.gax.rpc.ApiException;
+import com.google.api.gax.rpc.FixedHeaderProvider;
 import com.google.api.gax.rpc.HeaderProvider;
 import com.google.api.gax.rpc.InstantiatingWatchdogProvider;
 import com.google.api.gax.rpc.OperationCallable;
@@ -70,6 +71,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.RateLimiter;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.iam.v1.GetIamPolicyRequest;
@@ -232,6 +234,8 @@ private void awaitTermination() throws InterruptedException {
 private static final int DEFAULT_TIMEOUT_SECONDS = 30 * 60;
 private static final int DEFAULT_PERIOD_SECONDS = 10;
 private static final int GRPC_KEEPALIVE_SECONDS = 2 * 60;
+private static final String USER_AGENT_KEY = "user-agent";
+private static final String CLIENT_LIBRARY_LANGUAGE = "spanner-java";
 
 // TODO(weiranf): Remove this temporary endpoint once DirectPath goes to public beta.
 private static final String DIRECT_PATH_ENDPOINT = "aa423245250f2bbf.sandbox.googleapis.com:443";
@@ -297,9 +301,20 @@ public GapicSpannerRpc(final SpannerOptions options) {
 .build();
 
 HeaderProvider mergedHeaderProvider = options.getMergedHeaderProvider(internalHeaderProvider);
+Map<String, String> headersWithUserAgent =
+ImmutableMap.<String, String>builder()
+.put(
+USER_AGENT_KEY,
+CLIENT_LIBRARY_LANGUAGE
++ "/"
++ GaxProperties.getLibraryVersion(GapicSpannerRpc.class))
+.putAll(mergedHeaderProvider.getHeaders())
+.build();
+final HeaderProvider headerProviderWithUserAgent =
+FixedHeaderProvider.create(headersWithUserAgent);
 this.metadataProvider =
 SpannerMetadataProvider.create(
-mergedHeaderProvider.getHeaders(),
+headerProviderWithUserAgent.getHeaders(),
 internalHeaderProviderBuilder.getResourceHeaderKey());
 this.callCredentialsProvider = options.getCallCredentialsProvider();
 this.compressorName = options.getCompressorName();
@@ -338,7 +353,7 @@ public GapicSpannerRpc(final SpannerOptions options) {
 options.getInterceptorProvider(),
 SpannerInterceptorProvider.createDefault()))
 .withEncoding(compressorName))
-.setHeaderProvider(mergedHeaderProvider);
+.setHeaderProvider(headerProviderWithUserAgent);
 
 // TODO(weiranf): Set to true by default once DirectPath goes to public beta.
 if (shouldAttemptDirectPath()) {
@@ -478,8 +493,10 @@ private static void checkEmulatorConnection(
 throw SpannerExceptionFactory.newSpannerException(
 ErrorCode.UNAVAILABLE,
 String.format(
-"The environment variable SPANNER_EMULATOR_HOST has been set to %s, but no running emulator could be found at that address.\n"
-+ "Did you forget to start the emulator, or to unset the environment variable?",
+"The environment variable SPANNER_EMULATOR_HOST has been set to %s, but no running"
++ " emulator could be found at that address.\n"
++ "Did you forget to start the emulator, or to unset the environment"
++ " variable?",
 emulatorHost));
 }
 }