Serverless Storage

Serverless Storage is an easy to use file service for your Serverless Cloud applications. It can be used for storing any sort of binary data, and can be read back at any time.

Access to Serverless Storage is automatically included in the runtime environment, just import the storage interface from @serverless/cloud. Note, all storage operations are asynchronous, so async/await or .then is required for their use.

// Require the storage interface - CommonJS
const { storage } = require("@serverless/cloud");

// ES Modules
import { storage } from "@serverless/cloud";

Storing Files

Files can be stored just by passing the binary string to the write function. This could either be files uploaded via an HTTP request, or modifying any existing files and saving the changes. Note that if a file exists at the provided path, it will be replaced with the new file.

You can optionally not pass a path for the file, which will save it at the "root" directory.

Metadata and custom mimetypes can also be passed to be saved alongside your file.

await storage.write("/your/path/binaryData.ext", binaryData);
await storage.write('/your/path/binaryData.ext', binaryData, { metadata: { isThisAFile: true } })
await storage.write('/your/path/binaryData.ext', binaryData, { type: ‘application/octet-stream’ })
// this goes to root
await storage.write('/', binaryData)

Reading Files

Files can be read into memory as either a ReadableStream or a Buffer. If no options are passed, a ReadableStream is returned by default. Also included is readBuffer for ease of use, if you want to only use buffers without any extra arguments. To read the file, the absolute directory must be passed. If the file does not exist, undefined is returned.

const stream = await storage.read("binaryData.ext");

const buffer = await storage.read("binaryData.ext", { buffer: true });
const buffer = await storage.readBuffer("/your/path/binaryData.ext");

Copying and Moving Files

Files can be moved or copied to any directory within storage. If a destination directory does not exist, it will be created.

await storage.move("binaryData.ext", "bin");
// binaryData is now located at bin/binaryData.ext

await storage.copy("/bin/binaryData.ext", "bin-copy");
// binaryData is now located at both bin/binaryData.ext and bin-copy/binaryData.ext

Checking File Existence

To avoid a read operation, you may want to just check if a file exists before going forward.

const exists = await storage.exists("/bin/binaryData.ext");

const doesNotExist = await storage.exists("/not-real/binaryData.ext");

File Information and Metadata

You can retrieve when a file was last modified, size, content type, and any saved metadata using stat.

const { lastModified, size, metadata, type } = await storage.stat(
  "/your/path/binaryData.ext"
);

Listing Files

Files can be listed either as a whole or per directory.

To list all subdirectories recursively, you can pass a recursive option to list everything in all subdirectories under the initial path. To control page size, you can pass in a pageSize value to control how many files are returned per page, the default size is 100.

list returns an async generator, allowing for controlled iteration through your files.

const list = await storage.list("bin", { pageSize: 1 });
const page1 = await list.next();
// ['binaryData.ext']

const pages = await storage.list("/", { recursive: true, pageSize: 10 });
const allFiles = [];
for await (const page of pages) {
  allFiles.push(...page);
}
// ['bin/binaryData.ext', 'bin-copy/binaryData.ext']

Removing Files

Files can be removed using the remove function.

await storage.remove("/bin/binaryData.ext");

Upload and Download URLs

URLs for both uploading and downloading files from Storage can be generated using getDownloadUrl and getUploadUrl. A second parameter can be passed to set the expiration period for a URL, as a number in seconds. The default is 1 hour (3600s).

const downloadUrl = await storage.getDownloadUrl("bin-copy/binaryData.ext");

const longDownloadUrl = await storage.getDownloadUrl(
  "bin-copy/binaryData.ext",
  7200
);

const uploadUrl = await storage.getUploadUrl("bin-copy/doesNotExistYet.ext");

Listeners

You can listen for certain Storage events with storage.on. As of now, you can fire side-effects for write and remove events. The listener accepts any glob file patterns, and will react to all events with an asterisk *.

Storage events contain both the path of the file, and the event name (write or remove).

storage.on("write:user-uploads/*", async (event) => {
  // event = { path: user-uploads/picture.jpeg, name: 'write' }
});

storage.on("*", async (event) => {
  // reacts to all write/remove events
});

storage.on("write:*.txt", async (event) => {
  // reacts to all .txt file writes
});

Cloud Integrations with Storage

Storage can be used in tandem with other Cloud services, such as the API.

• API