Add an option to use pre-encoded env vars

lib/moduleEncoding.js

@@ -24,6 +24,8 @@ const path = require('path');
 
 const DEFAULT_START_ALIGNMENT = 8;
 
+const MAX_ENV_VARS_ASSET_DATA_SIZE = 16 * 1024;
+
 function moduleFunctionToString(func) {
 	switch (func) {
 		case ModuleInfo.FunctionType.NONE: {
@@ -1683,8 +1685,6 @@ async function createProtectedModule(module, certificate) {
  * @returns {Promise<Buffer>} Asset data.
  */
 async function encodeEnvVarsAsset(vars, snapshot = undefined) {
-	const maxAssetSize = 16 * 1024;
-
 	if (!vars || typeof vars !== 'object') {
 		throw new Error('Expected variable values to be an object');
 	}
@@ -1700,7 +1700,7 @@ async function encodeEnvVarsAsset(vars, snapshot = undefined) {
 			throw new Error(`Variable value is not a string: ${name}`);
 		}
 		approxSize += name.length + val.length;
-		if (approxSize > maxAssetSize) {
+		if (approxSize > MAX_ENV_VARS_ASSET_DATA_SIZE) {
 			throw new Error('Asset exceeds the maximum size');
 		}
 	}
@@ -1733,7 +1733,7 @@ async function encodeEnvVarsAsset(vars, snapshot = undefined) {
 		updatedAt
 	})).finish();
 
-	if (assetData.length > maxAssetSize) {
+	if (assetData.length > MAX_ENV_VARS_ASSET_DATA_SIZE) {
 		throw new Error('Asset exceeds the maximum size');
 	}
 
@@ -1743,7 +1743,8 @@ async function encodeEnvVarsAsset(vars, snapshot = undefined) {
 /**
  * Create an asset module containing environment variables.
  *
- * @param {Object} vars Variable values.
+ * @param {Object|Buffer} vars Object with variable values or buffer with application variables
+ *        encoded via `encodeEnvVarsAsset()`.
  * @param {Object} [snapshot] Snapshot details. If not provided, the asset will be marked as
  *        containing application variables as opposed to a snapshot of cloud variables.
  * @param {String|Buffer} snapshot.hash Snapshot hash. Can be a buffer or hex-encoded string.
@@ -1752,7 +1753,18 @@ async function encodeEnvVarsAsset(vars, snapshot = undefined) {
  * @returns {Promise<Buffer>} Module binary.
  */
 async function createEnvVarsAssetModule(vars, snapshot = undefined) {
-	const assetData = await encodeEnvVarsAsset(vars, snapshot);
+	let assetData;
+	if (Buffer.isBuffer(vars)) {
+		if (vars.length > MAX_ENV_VARS_ASSET_DATA_SIZE) {
+			throw new Error('Asset exceeds the maximum size');
+		}
+		if (snapshot) {
+			throw new Error('Cannot set snapshot details in already encoded asset data');
+		}
+		assetData = vars;
+	} else {
+		assetData = await encodeEnvVarsAsset(vars, snapshot);
+	}
 
 	const assetModule = await createAssetModule(assetData, 'env-vars', {
 		type: snapshot ? ModuleInfo.AssetType.ENV_VARS_SNAPSHOT : ModuleInfo.AssetType.ENV_VARS_APP,

specs/lib/moduleEncoding.spec.js

@@ -16,6 +16,7 @@ const {
 	isAssetValid,
 	AssetLimitError,
 	createProtectedModule,
+	encodeEnvVarsAsset,
 	createEnvVarsAssetModule
 } = require('../../lib/moduleEncoding');
 
@@ -993,6 +994,16 @@ describe('moduleEncoding', () => {
 			await validateAsset(mod, {});
 		});
 
+		it('can take a buffer with pre-encoded variables', async () => {
+			const vars = {
+				'VAR1': 'abc',
+				'VAR2': '123'
+			};
+			const data = await encodeEnvVarsAsset(vars);
+			const mod = await createEnvVarsAssetModule(data);
+			await validateAsset(mod, vars);
+		});
+
 		describe('error handling', () => {
 			it('invalid variable name', async () => {
 				const msg = 'Invalid variable name: ';