GCSFilesystem

Stores files in Google Cloud Storage.

info

For interface details, see WorkspaceFilesystem Interface.

Installation

npm install @mastra/gcs

Usage

Add a GCSFilesystem to a workspace and assign it to an agent:

import { Agent } from '@mastra/core/agent';
import { Workspace } from '@mastra/core/workspace';
import { GCSFilesystem } from '@mastra/gcs';

const workspace = new Workspace({
  filesystem: new GCSFilesystem({
    bucket: 'my-gcs-bucket',
    projectId: 'my-project-id',
    credentials: JSON.parse(process.env.GCS_SERVICE_ACCOUNT_KEY),
  }),
});

const agent = new Agent({
  name: 'file-agent',
  model: 'anthropic/claude-opus-4-5',
  workspace,
});

Using Application Default Credentials

If running on Google Cloud or with gcloud CLI configured, you can omit credentials:

import { GCSFilesystem } from '@mastra/gcs';

const filesystem = new GCSFilesystem({
  bucket: 'my-gcs-bucket',
  // Uses Application Default Credentials automatically
});

Application Default Credentials (ADC) automatically discovers credentials in this order:

1. GOOGLE_APPLICATION_CREDENTIALS environment variable (path to a service account key file)
2. Default service account when running on GCP (Compute Engine, Cloud Run, GKE, etc.)
3. User credentials from gcloud auth application-default login (for local development)

Using a Key File Path

You can also pass a path to a service account key file:

import { GCSFilesystem } from '@mastra/gcs';

const filesystem = new GCSFilesystem({
  bucket: 'my-gcs-bucket',
  projectId: 'my-project-id',
  credentials: '/path/to/service-account-key.json',
});

Constructor parameters

bucket:

string

GCS bucket name

projectId?:

string

GCS project ID. Required when using service account credentials.

credentials?:

object | string

Service account key JSON object or path to key file. If not provided, uses Application Default Credentials.

prefix?:

string

Optional prefix for all keys (acts like a subdirectory)

id?:

string

= Auto-generated

Unique identifier for this filesystem instance

displayName?:

string

Human-friendly display name for the UI

readOnly?:

boolean

= false

When true, all write operations are blocked

endpoint?:

string

Custom API endpoint URL. Used for local development with emulators.

Properties

id:

string

Filesystem instance identifier

name:

string

Provider name ('GCSFilesystem')

provider:

string

Provider identifier ('gcs')

bucket:

string

The GCS bucket name

readOnly:

boolean | undefined

Whether the filesystem is in read-only mode

Methods

GCSFilesystem implements the WorkspaceFilesystem interface, providing all standard filesystem methods:

• readFile(path, options?) - Read file contents
• writeFile(path, content, options?) - Write content to a file
• appendFile(path, content) - Append content to a file
• deleteFile(path, options?) - Delete a file
• copyFile(src, dest, options?) - Copy a file
• moveFile(src, dest, options?) - Move or rename a file
• mkdir(path, options?) - Create a directory
• rmdir(path, options?) - Remove a directory
• readdir(path, options?) - List directory contents
• exists(path) - Check if a path exists
• stat(path) - Get file or directory metadata

init()

Initialize the filesystem. Verifies bucket access and credentials.

await filesystem.init();

getInfo()

Returns metadata about this filesystem instance.

const info = filesystem.getInfo();
// { id: '...', name: 'GCSFilesystem', provider: 'gcs', status: 'ready' }

getMountConfig()

Returns the mount configuration for sandboxes that support mounting this filesystem type.

const config = filesystem.getMountConfig();
// { type: 'gcs', bucket: 'my-bucket', ... }

Mounting in E2B Sandboxes

GCSFilesystem can be mounted into E2B sandboxes, making the bucket accessible as a local directory:

import { Workspace } from '@mastra/core/workspace';
import { GCSFilesystem } from '@mastra/gcs';
import { E2BSandbox } from '@mastra/e2b';

const workspace = new Workspace({
  mounts: {
    '/data': new GCSFilesystem({
      bucket: 'my-gcs-bucket',
      projectId: 'my-project-id',
      credentials: JSON.parse(process.env.GCS_SERVICE_ACCOUNT_KEY),
    }),
  },
  sandbox: new E2BSandbox({ id: 'dev-sandbox' }),
});

See E2BSandbox reference for more details on mounting.

Related

• WorkspaceFilesystem interface
• S3Filesystem reference
• E2BSandbox reference
• Workspace overview