chore(spanner): migrate grpc-gcp into google-cloud-java

.github/CODEOWNERS

@@ -9,6 +9,7 @@
 /java-vertexai/   @googleapis/vertexai-team @googleapis/cloud-sdk-java-team
 /java-bigquerystorage/ @googleapis/bigquery-team @googleapis/cloud-sdk-java-team
 /java-bigquery/ @googleapis/bigquery-team @googleapis/cloud-sdk-java-team
+/grpc-gcp-java/ @googleapis/spanner-team @googleapis/cloud-sdk-java-team
 /java-spanner/ @googleapis/spanner-team @googleapis/cloud-sdk-java-team
 /java-spanner-jdbc/ @googleapis/spanner-team @googleapis/cloud-sdk-java-team
 /google-auth-library-java/ @googleapis/cloud-sdk-auth-team @googleapis/cloud-sdk-java-team @googleapis/aion-team

.github/workflows/ci.yaml

@@ -36,8 +36,8 @@ jobs:
       with:
         filters: |
           src:
-            - '!(google-auth-library-java|java-bigquery|java-bigquerystorage|java-bigtable|java-datastore|java-firestore|java-logging|java-logging-logback|java-pubsub|java-spanner|java-storage)/**/*.java'
-            - '!(google-auth-library-java|java-bigquery|java-bigquerystorage|java-bigtable|java-datastore|java-firestore|java-logging|java-logging-logback|java-pubsub|java-spanner|java-storage)/**/pom.xml'
+            - '!(google-auth-library-java|grpc-gcp-java|java-bigquery|java-bigquerystorage|java-bigtable|java-datastore|java-firestore|java-logging|java-logging-logback|java-pubsub|java-spanner|java-storage)/**/*.java'
+            - '!(google-auth-library-java|grpc-gcp-java|java-bigquery|java-bigquerystorage|java-bigtable|java-datastore|java-firestore|java-logging|java-logging-logback|java-pubsub|java-spanner|java-storage)/**/pom.xml'
             - 'pom.xml'
           ci:
             - '.github/workflows/ci.yaml'
@@ -123,6 +123,8 @@ jobs:
         filters: |
           google-auth-library-java:
             - 'google-auth-library-java/**'
+          grpc-gcp-java:
+            - 'grpc-gcp-java/**'
           java-bigquery:
             - 'java-bigquery/**'
             - 'google-auth-library-java/**/*.java'
@@ -160,6 +162,7 @@ jobs:
             - 'sdk-platform-java/gapic-generator-java-pom-parent/pom.xml'
           java-spanner:
             - 'java-spanner/**'
+            - 'grpc-gcp-java/**'
             - 'google-auth-library-java/**/*.java'
             - 'google-auth-library-java/**/pom.xml'
             - 'sdk-platform-java/**/*.java'

generation/check_non_release_please_versions.sh

@@ -19,6 +19,7 @@ for pomFile in $(find . -mindepth 2 -name pom.xml | sort ); do
       [[ "${pomFile}" =~ .*java-spanner.* ]] || \
       [[ "${pomFile}" =~ .*java-spanner-jdbc.* ]] || \
       [[ "${pomFile}" =~ .*google-auth-library-java.* ]] || \
+      [[ "${pomFile}" =~ .*grpc-gcp.* ]] || \
       [[ "${pomFile}" =~ .*java-storage.* ]] || \
       [[ "${pomFile}" =~ .*java-storage-nio.* ]] || \
       [[ "${pomFile}" =~ .*java-pubsub.* ]] || \

grpc-gcp-java/.repo-metadata.json

@@ -0,0 +1,17 @@
+{
+  "api_shortname": "grpc-gcp",
+  "name_pretty": "gRPC GCP Extension",
+  "product_documentation": "https://github.com/GoogleCloudPlatform/grpc-gcp-java",
+  "api_description": "gRPC extension library for Google Cloud Platform clients.",
+  "client_documentation": "https://cloud.google.com/java/docs/reference/grpc-gcp/latest/overview",
+  "release_level": "stable",
+  "transport": "grpc",
+  "language": "java",
+  "repo": "googleapis/google-cloud-java",
+  "repo_short": "google-cloud-java",
+  "distribution_name": "com.google.cloud:grpc-gcp",
+  "library_type": "OTHER",
+  "codeowner_team": "@googleapis/cloud-sdk-java-team",
+  "recommended_package": "com.google.cloud.grpc",
+  "min_java_version": 8
+}

grpc-gcp-java/CHANGELOG.md

@@ -0,0 +1,125 @@
+# Changelog
+
+## 1.10.0 (2026-04-10)
+
+### Fixes
+
+* Use power-of-two random choices for channel selection to avoid thundering herd
+
+
+## 1.9.2 (2026-03-21)
+
+### Fixes
+
+* Use daemon threads for grpc-gcp background executors by default
+
+### Features
+
+* Support of Unbind manual affinity keys after terminal calls
+
+
+## 1.9.1 (2025-12-27)
+
+### Fixes
+
+* Fix race for metrics values (#228)
+
+## 1.9.0 (2025-12-15)
+
+### Features
+
+* Set channelID in call options for downstream interceptors (#225)
+
+## 1.8.0 (2025-12-12)
+
+### Features
+
+* End to end fallback (#221)
+* Migrate opencensus metrics to opentelemetry (#222)
+
+## 1.7.0 (2025-09-23)
+
+### Features
+
+* Dynamic channel pool scaling (#194)
+
+## 1.6.1 (2024-06-17)
+
+### Features
+
+* Log manual affinity and disabling affinity (#177)
+
+## 1.6.0 (2024-05-09)
+
+### Features
+
+* Affinity keys cleanup. Allow setting keys lifetime (#174)
+* Manual affinity via call options or context (#175)
+
+## 1.5.0 (2023-11-08)
+
+### Features
+
+* Add disable affinity feature (#167)
+
+## 1.4.1 (2023-01-30)
+
+### Fixes
+
+- Support common labels for multi-endpoint metrics (#160)
+
+## 1.4.0 (2023-01-27)
+
+### Features
+
+- MultiEndpoint metrics (#158)
+
+## 1.3.2 (2022-12-02)
+
+### Fixes
+
+* Fix race condition when running and adding state change callbacks. (#155)
+
+## 1.3.1 (2022-10-24)
+
+### Fixes
+
+* MultiEndpoint: allow specifying protocol in the endpoint. (#151)
+
+## 1.3.0 (2022-10-12)
+
+### Features
+
+* Add switching delay to GcpMultiEndpointChannel. (#145)
+* Look for a multi-endpoint specified in gRPC context. (#149)
+
+## 1.2.0 (2022-07-18)
+
+### Features
+
+* multi-endpoint (#135).
+* round-robin for bind calls (#127).
+* minSize of the channel pool (#134).
+* detailed logs (#133).
+* log metrics (#131).
+* map a key to current channel when bound call arrives but no mapping for the
+key exists (#132).
+* consolidate channel pool config in the GcpChannelPoolOptions (#109).
+
+## 1.1.0 (2021-07-20)
+
+### Features
+
+* improve bind/unbind logic.
+* improve getChannelRef performance for calls without channel affinity.
+* more accurate affinity counts.
+* allow to rebind a key to another channel and adjust affinity counts accordingly.
+
+## 1.0.0 (2021-06-11)
+
+### Features
+
+* gRPC channel pool with configurable channel affinity.
+* provide a channel with minimum active streams for a new call.
+* an optional fallback from non-ready channel to a ready channel.
+* an option to detect unresponsive channels.

grpc-gcp-java/README.md

@@ -0,0 +1,121 @@
+# gRPC-GCP for Java
+
+grpc-gcp provides gRPC support for Google Cloud Clients.
+
+This module is currently used by the Google Cloud Spanner client library to provide
+gRPC-GCP channel pooling and related transport behavior. It is published separately
+as `com.google.cloud:grpc-gcp` because Spanner exposes grpc-gcp types in its public
+API.
+
+## Usage
+
+Use Spanner API as an example.
+
+First, Create a json file defining API configuration, with ChannelPoolConfig and MethodConfig.
+
+```json
+{
+  "channelPool": {
+    "maxSize": 3,
+    "maxConcurrentStreamsLowWatermark": 0
+  },
+  "method": [
+    {
+      "name": [ "google.spanner.v1.Spanner/CreateSession" ],
+      "affinity": {
+        "command": "BIND",
+        "affinityKey": "name"
+      }
+    },
+    {
+      "name": [ "google.spanner.v1.Spanner/GetSession" ],
+      "affinity": {
+        "command": "BOUND",
+        "affinityKey": "name"
+      }
+    },
+    {
+      "name": [ "google.spanner.v1.Spanner/DeleteSession" ],
+      "affinity": {
+        "command": "UNBIND",
+        "affinityKey": "name"
+      }
+    }
+  ]
+}
+```
+
+Initialize `GcpManagedChannel` based on this API config file.
+
+```java
+String API_CONFIG_FILE = "api_config_file.json"
+String SPANNER_TARGET = "spanner.googleapis.com";
+...
+
+ManagedChannelBuilder delegateChannelBuilder = ManagedChannelBuilder.forAddress(SPANNER_TARGET, 443);
+GcpManagedChannelBuilder gcpBuilder = 
+  GcpManagedChannelBuilder.forDelegateBuilder(delegateChannelBuilder)
+                          .withApiConfigJsonFile(jsonApiConfig);
+ManagedChannel gcpChannel = gcpBuilder.build();
+```
+
+Create Cloud API stub using `GcpManagedChannel`.
+
+```java
+GoogleCredentials creds = getCreds();
+SpannerBlockingStub stub =
+    SpannerGrpc.newBlockingStub(gcpChannel)
+               .withCallCredentials(MoreCallCredentials.from(creds));
+```
+
+## Build from source
+
+Download source.
+
+```sh
+git clone https://github.com/googleapis/google-cloud-java.git && cd google-cloud-java/grpc-gcp-java
+```
+
+Build project with unit tests.
+
+```sh
+mvn verify
+```
+
+Install the jar to your local Maven repository.
+
+```sh
+mvn install
+```
+
+## Test
+
+Setup credentials. See [Getting Started With Authentication](https://cloud.google.com/docs/authentication/getting-started) for more details.
+
+```sh
+export GOOGLE_APPLICATION_CREDENTIALS=path/to/key.json
+```
+
+```sh
+export GCP_PROJECT_ID=project_id
+```
+
+Run unit tests.
+
+```sh
+mvn test
+```
+
+Integration tests are kept as source references but are not wired into the default monorepo Maven lifecycle.
+
+## Publish
+
+This artifact is released by the `google-cloud-java` monorepo release pipeline.
+
+## Code Format
+
+Run google-java-format
+
+```sh
+mvn fmt:format
+```