Merge pull request #37 from balena-io-modules/data-directory-false

Support using memory storage by passing dataDirectory: false

README.md

@@ -50,7 +50,7 @@ Documentation
 | Param | Type | Description |
 | --- | --- | --- |
 | options | <code>Object</code> | options |
-| options.dataDirectory | <code>string</code> | the directory to use for storage in Node.js. Ignored in the browser. |
+| [options.dataDirectory] | <code>String</code> \| <code>False</code> | the directory to use for storage in Node.js or false to create an isolated in memory instance. Values other than false are ignored in the browser. |
 
 **Example**  
 ```js

lib/index.browser.ts

@@ -1,15 +1,22 @@
 import * as localStore from './stores/local-storage';
 import * as virtualStore from './stores/virtual-storage';
 import { getStorage as $getStorage } from './storage';
-import type { BalenaSettingsStorage } from './types';
+import type {
+	BalenaSettingsStorageOptions,
+	BalenaSettingsStorage,
+} from './types';
 
-export type { BalenaSettingsStorage } from './types';
+export type {
+	BalenaSettingsStorageOptions,
+	BalenaSettingsStorage,
+} from './types';
 
-export const getStorage = (options: {
-	dataDirectory?: string;
-}): BalenaSettingsStorage => {
-	const store = localStore.isSupported()
-		? localStore.createStorage(options?.dataDirectory)
-		: virtualStore.createStore(options?.dataDirectory);
+export const getStorage = (
+	options: BalenaSettingsStorageOptions,
+): BalenaSettingsStorage => {
+	const store =
+		options?.dataDirectory === false || !localStore.isSupported()
+			? virtualStore.createStore()
+			: localStore.createStorage(options?.dataDirectory);
 	return $getStorage(store);
 };

lib/index.ts

@@ -1,25 +1,42 @@
-import * as nodeStore from './stores/node-storage';
 import { getStorage as $getStorage } from './storage';
-import type { BalenaSettingsStorage, StorageLike } from './types';
+import type {
+	BalenaSettingsStorage,
+	BalenaSettingsStorageOptions,
+	StorageLike,
+} from './types';
 
-export type { BalenaSettingsStorage } from './types';
+export type {
+	BalenaSettingsStorageOptions,
+	BalenaSettingsStorage,
+} from './types';
 
-export const getStorage = (options: {
-	dataDirectory?: string;
-}): BalenaSettingsStorage => {
+// use dynamic imports so that node apps have less files to read on startup.
+const lazyImport = {
+	virtual: () =>
+		require('./stores/virtual-storage') as typeof import('./stores/virtual-storage'),
+	local: () =>
+		require('./stores/local-storage') as typeof import('./stores/local-storage'),
+	node: () =>
+		require('./stores/node-storage') as typeof import('./stores/node-storage'),
+};
+
+export const getStorage = (
+	options: BalenaSettingsStorageOptions,
+): BalenaSettingsStorage => {
 	let store: StorageLike;
-	if (typeof window !== 'undefined') {
-		// use dynamic imports so that node apps have less files to read on startup.
-		const localStore =
-			require('./stores/local-storage') as typeof import('./stores/local-storage');
+	if (options?.dataDirectory === false) {
+		store = lazyImport.virtual().createStore();
+	} else if (typeof window !== 'undefined') {
+		// Even though we specify an alternative file for this in the package.json's `browser` field
+		// we still need to handle the `isBrowser` case in the default file for the case that the
+		// bundler doesn't support/use the `browser` field.
+		const localStore = lazyImport.local();
 		store = localStore.isSupported()
 			? localStore.createStorage(options?.dataDirectory)
-			: (
-					require('./stores/virtual-storage') as typeof import('./stores/virtual-storage')
-			  ).createStore(options?.dataDirectory);
+			: lazyImport.virtual().createStore(options?.dataDirectory);
 	} else {
 		// Fallback to filesystem based storage if not in the browser.
-		store = nodeStore.createStorage(options?.dataDirectory);
+		store = lazyImport.node().createStorage(options?.dataDirectory);
 	}
 	return $getStorage(store);
 };

lib/storage.ts

@@ -14,21 +14,21 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import { BalenaSettingsStorage, StorageLike } from './types';
+import { BalenaSettingsPermissionError } from 'balena-errors';
+
 /**
  * @module storage
  */
 
-import { BalenaSettingsStorage, StorageLike } from './types';
-import { BalenaSettingsPermissionError } from 'balena-errors';
-
 /**
  * @summary Get an instance of storage module
  * @function
  * @static
  * @public
  *
- * @param {Object?} options - options
- * @param {string?} options.dataDirectory - the directory to use for storage in Node.js. Ignored in the browser.
+ * @param {Object} options - options
+ * @param {String|False} [options.dataDirectory] - the directory to use for storage in Node.js or false to create an isolated in memory instance. Values other than false are ignored in the browser.
  *
  * @return {storage}
  * @example

lib/types.ts

@@ -1,3 +1,7 @@
+export interface BalenaSettingsStorageOptions {
+	dataDirectory?: string | false;
+}
+
 export interface BalenaSettingsStorage {
 	set: (name: string, value: any) => Promise<void>;
 	get: (name: string) => Promise<string | number | object | undefined>;