Added implementation for Google Cloud Store

.gitignore

@@ -2,6 +2,7 @@ bazel-*
 target/
 .vscode/
 .zed
+.idea/
 .cache
 .terraform*
 .config

nativelink-config/examples/gcs_backend.json5

@@ -0,0 +1,168 @@
+{
+  "stores": {
+    "CAS_MAIN_STORE": {
+      "verify": {
+        "backend": {
+          "dedup": {
+            "index_store": {
+              "fast_slow": {
+                "fast": {
+                  "filesystem": {
+                    "content_path": "/tmp/nativelink/data/content_path-index",
+                    "temp_path": "/tmp/nativelink/data/tmp_path-index",
+                    "eviction_policy": {
+                      // 500mb.
+                      "max_bytes": 500000000
+                    }
+                  }
+                },
+                "slow": {
+                  "experimental_gcs_store": {
+                    "project_id": "inbound-entity-447014-k2",
+                    "bucket": "test-bucket-aman-nativelink",
+                    "key_prefix": "test-prefix-index/",
+                    "retry": {
+                      "max_retries": 6,
+                      "delay": 0.3,
+                      "jitter": 0.5
+                    },
+                    "max_concurrent_uploads": 10
+                  }
+                }
+              }
+            },
+            "content_store": {
+              "compression": {
+                "compression_algorithm": {
+                  "lz4": {}
+                },
+                "backend": {
+                  "fast_slow": {
+                    "fast": {
+                      "filesystem": {
+                        "content_path": "/tmp/nativelink/data/content_path-content",
+                        "temp_path": "/tmp/nativelink/data/tmp_path-content",
+                        "eviction_policy": {
+                          "max_bytes": 2000000000
+                        }
+                      }
+                    },
+                    "slow": {
+                      "experimental_gcs_store": {
+                        "project_id": "inbound-entity-447014-k2",
+                        "bucket": "test-bucket-aman-nativelink",
+                        "key_prefix": "test-prefix-dedup-cas/",
+                        "retry": {
+                          "max_retries": 6,
+                          "delay": 0.3,
+                          "jitter": 0.5
+                        },
+                        "max_concurrent_uploads": 10
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        },
+        "verify_size": true
+      }
+    },
+    "AC_MAIN_STORE": {
+      "fast_slow": {
+        "fast": {
+          "memory": {
+            "eviction_policy": {
+              "max_bytes": 100000000
+            }
+          },
+          "filesystem": {
+            "content_path": "/tmp/nativelink/data/content_path-ac",
+            "temp_path": "/tmp/nativelink/data/tmp_path-ac",
+            "eviction_policy": {
+              // 500mb.
+              "max_bytes": 500000000
+            }
+          }
+        },
+        "slow": {
+          "experimental_gcs_store": {
+            "project_id": "inbound-entity-447014-k2",
+            // Name of the bucket to upload to.
+            "bucket": "test-bucket-aman-nativelink",
+            "key_prefix": "test-prefix-ac/",
+            "retry": {
+              "max_retries": 6,
+              "delay": 0.3,
+              "jitter": 0.5
+            },
+            "max_concurrent_uploads": 10
+          }
+        }
+      }
+    },
+  },
+  "schedulers": {
+    "MAIN_SCHEDULER": {
+      "simple": {
+        "supported_platform_properties": {
+          "cpu_count": "minimum",
+          "memory_kb": "minimum",
+          "network_kbps": "minimum",
+          "disk_read_iops": "minimum",
+          "disk_read_bps": "minimum",
+          "disk_write_iops": "minimum",
+          "disk_write_bps": "minimum",
+          "shm_size": "minimum",
+          "gpu_count": "minimum",
+          "gpu_model": "exact",
+          "cpu_vendor": "exact",
+          "cpu_arch": "exact",
+          "cpu_model": "exact",
+          "kernel_version": "exact",
+          "docker_image": "priority",
+          "lre-rs": "priority"
+        }
+      }
+    }
+  },
+  "servers": [{
+    "listener": {
+      "http": {
+        "socket_address": "0.0.0.0:50051"
+      }
+    },
+    "services": {
+      "cas": {
+        "main": {
+          "cas_store": "CAS_MAIN_STORE"
+        }
+      },
+      "ac": {
+        "main": {
+          "ac_store": "AC_MAIN_STORE"
+        }
+      },
+      "execution": {
+        "main": {
+          "cas_store": "CAS_MAIN_STORE",
+          "scheduler": "MAIN_SCHEDULER"
+        }
+      },
+      "capabilities": {
+        "main": {
+          "remote_execution": {
+            "scheduler": "MAIN_SCHEDULER"
+          }
+        }
+      },
+      "bytestream": {
+        "cas_stores": {
+          "main": "CAS_MAIN_STORE"
+        }
+      },
+      "health": {}
+    }
+  }]
+}

nativelink-config/src/stores.rs

@@ -78,6 +78,27 @@ pub enum StoreSpec {
     ///
     experimental_s3_store(S3Spec),
 
+    /// GCS store will use Google's GCS service as a backend to store
+    /// the files. This configuration can be used to share files
+    /// across multiple instances.
+    ///
+    /// **Example JSON Config:**
+    /// ```json
+    /// "experimental_gcs_store": {
+    ///   "project_id": "sample-project",
+    ///   "bucket": "test-bucket",
+    ///   "key_prefix": "test-prefix-index/",
+    ///   "retry": {
+    ///     "max_retries": 6,
+    ///     "delay": 0.3,
+    ///     "jitter": 0.5
+    ///   },
+    ///   "max_concurrent_uploads": 10
+    /// }
+    /// ```
+    ///
+    experimental_gcs_store(GcsSpec),
+
     /// Verify store is used to apply verifications to an underlying
     /// store implementation. It is strongly encouraged to validate
     /// as much data as you can before accepting data from a client,
@@ -787,6 +808,78 @@ pub struct S3Spec {
     pub disable_http2: bool,
 }
 
+#[derive(Serialize, Deserialize, Debug, Default, Clone)]
+#[serde(deny_unknown_fields)]
+pub struct GcsSpec {
+    /// Project ID for the GCS service
+    #[serde(default, deserialize_with = "convert_string_with_shellexpand")]
+    pub project_id: String,
+
+    /// Bucket name to use as the backend
+    #[serde(default, deserialize_with = "convert_string_with_shellexpand")]
+    pub bucket: String,
+
+    /// If you wish to prefix the location in GCS. If None, no prefix will be used.
+    #[serde(default)]
+    pub key_prefix: Option<String>,
+
+    /// Retry configuration to use when a network request fails.
+    #[serde(default)]
+    pub retry: Retry,
+
+    /// If the number of seconds since the `last_modified` time of the object
+    /// is greater than this value, the object will not be considered
+    /// "existing". This allows for external tools to delete objects that
+    /// have not been uploaded in a long time. If a client receives a `NotFound`
+    /// the client should re-upload the object.
+    ///
+    /// There should be sufficient buffer time between how long the expiration
+    /// configuration of the external tool is and this value. Keeping items
+    /// around for a few days is generally a good idea.
+    ///
+    /// Default: 0. Zero means never consider an object expired.
+    #[serde(default, deserialize_with = "convert_duration_with_shellexpand")]
+    pub consider_expired_after_s: u32,
+
+    /// The maximum buffer size to retain in case of a retryable error
+    /// during upload. Setting this to zero will disable upload buffering;
+    /// this means that in the event of a failure during upload, the entire
+    /// upload will be aborted and the client will likely receive an error.
+    ///
+    /// Default: 5MB.
+    pub max_retry_buffer_per_request: Option<usize>,
+
+    /// Size of chunks for resumeable uploads (in bytes).
+    /// Must be a multiple of 256 KB.
+    ///
+    /// Default: 8MB.
+    pub resumable_chunk_size: Option<usize>,
+
+    /// Maximum number of concurrent uploads for resumable operations
+    ///
+    /// Default: 10.
+    pub max_concurrent_uploads: Option<usize>,
+
+    /// Optional endpoint override for testing
+    /// Example: "localhost:8080" for local development
+    ///
+    /// Default: None (uses production GCS endpoint)
+    #[serde(default)]
+    pub endpoint: Option<String>,
+
+    /// Allow unencrypted HTTP connections. Only use this for local testing.
+    ///
+    /// Default: false
+    #[serde(default)]
+    pub insecure_allow_http: bool,
+
+    /// Disable http/2 connections and only use http/1.1.
+    ///
+    /// Default: false
+    #[serde(default)]
+    pub disable_http2: bool,
+}
+
 #[allow(non_camel_case_types)]
 #[derive(Serialize, Deserialize, Debug, Clone, Copy)]
 pub enum StoreType {