make env vars a bit easier to understand/follow in adapter-node (#4360)

* make env vars a bit easier to understand/follow in adapter-node

* tidy up types

* fail noisily if opts.env is provided

* changeset

* update docs

* lint

* rename env in README

* custom prefix instead of names themselves

* tweak changeset

* typo

* oops

* lint

* error if env var namespace is already occupied

* Update packages/adapter-node/tsconfig.json

Co-authored-by: Maurício Kishi <mrkishi@users.noreply.github.com>

Co-authored-by: mrkishi <mauriciokishi@gmail.com>
Co-authored-by: Maurício Kishi <mrkishi@users.noreply.github.com>

.changeset/thirty-kings-yell.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-node': patch
+---
+
+[breaking] Replace `options.env` with `options.envPrefix`

packages/adapter-node/README.md

@@ -83,18 +83,7 @@ export default {
 			// default options are shown
 			out: 'build',
 			precompress: false,
-			env: {
-				path: 'SOCKET_PATH',
-				host: 'HOST',
-				port: 'PORT',
-				origin: 'ORIGIN',
-				xffDepth: 'XFF_DEPTH',
-				headers: {
-					address: 'ADDRESS_HEADER',
-					protocol: 'PROTOCOL_HEADER',
-					host: 'HOST_HEADER'
-				}
-			}
+			envPrefix: ''
 		})
 	}
 };
@@ -108,28 +97,18 @@ The directory to build the server to. It defaults to `build` — i.e. `node buil
 
 Enables precompressing using gzip and brotli for assets and prerendered pages. It defaults to `false`.
 
-### env
+### envPrefix
 
-If you need to change the name of the environment variables used to configure the deployment (for example, you need to run multiple deployments from a single environment), you can tell the app to expect custom environment variables using the `env` option:
+If you need to change the name of the environment variables used to configure the deployment (for example, to deconflict with environment variables you don't control), you can specify a prefix:
 
 ```js
-env: {
-	host: 'MY_HOST_VARIABLE',
-	port: 'MY_PORT_VARIABLE',
-	origin: 'MY_ORIGINURL',
-	xffDepth: 'MY_XFF_DEPTH',
-	headers: {
-		address: 'MY_ADDRESS_HEADER',
-		protocol: 'MY_PROTOCOL_HEADER',
-		host: 'MY_HOST_HEADER'
-	}
-}
+envPrefix: 'MY_CUSTOM_';
 ```
 
 ```
-MY_HOST_VARIABLE=127.0.0.1 \
-MY_PORT_VARIABLE=4000 \
-MY_ORIGINURL=https://my.site \
+MY_CUSTOM_HOST=127.0.0.1 \
+MY_CUSTOM_PORT=4000 \
+MY_CUSTOM_ORIGIN=https://my.site \
 node build
 ```
 

packages/adapter-node/index.d.ts

@@ -1,26 +1,13 @@
 import { Adapter } from '@sveltejs/kit';
 
 declare global {
-	const HOST_ENV: string;
-	const PATH_ENV: string;
-	const PORT_ENV: string;
+	const ENV_PREFIX: string;
 }
 
 interface AdapterOptions {
 	out?: string;
 	precompress?: boolean;
-	env?: {
-		path?: string;
-		host?: string;
-		port?: string;
-		origin?: string;
-		xffDepth?: string;
-		headers?: {
-			address?: string;
-			protocol?: string;
-			host?: string;
-		};
-	};
+	envPrefix?: string;
 }
 
 declare function plugin(options?: AdapterOptions): Adapter;

packages/adapter-node/index.js

@@ -10,22 +10,17 @@ const pipe = promisify(pipeline);
 const files = fileURLToPath(new URL('./files', import.meta.url).href);
 
 /** @type {import('.')} */
-export default function ({
-	out = 'build',
-	precompress,
-	env: {
-		path: path_env = 'SOCKET_PATH',
-		host: host_env = 'HOST',
-		port: port_env = 'PORT',
-		origin: origin_env = 'ORIGIN',
-		xffDepth: xff_depth_env = 'XFF_DEPTH',
-		headers: {
-			address: address_header_env = 'ADDRESS_HEADER',
-			protocol: protocol_header_env = 'PROTOCOL_HEADER',
-			host: host_header_env = 'HOST_HEADER'
-		} = {}
-	} = {}
-} = {}) {
+export default function (opts = {}) {
+	// TODO remove for 1.0
+	// @ts-expect-error
+	if (opts.env) {
+		throw new Error(
+			'options.env has been removed in favour of options.envPrefix. Consult the adapter-node README: https://github.com/sveltejs/kit/tree/master/packages/adapter-node'
+		);
+	}
+
+	const { out = 'build', precompress, envPrefix = '' } = opts;
+
 	return {
 		name: '@sveltejs/adapter-node',
 
@@ -49,14 +44,7 @@ export default function ({
 				replace: {
 					SERVER: './server/index.js',
 					MANIFEST: './manifest.js',
-					PATH_ENV: JSON.stringify(path_env),
-					HOST_ENV: JSON.stringify(host_env),
-					PORT_ENV: JSON.stringify(port_env),
-					ORIGIN: origin_env ? `process.env[${JSON.stringify(origin_env)}]` : 'undefined',
-					XFF_DEPTH_ENV: xff_depth_env,
-					PROTOCOL_HEADER: JSON.stringify(protocol_header_env),
-					HOST_HEADER: JSON.stringify(host_header_env),
-					ADDRESS_HEADER: JSON.stringify(address_header_env)
+					ENV_PREFIX: JSON.stringify(envPrefix)
 				}
 			});
 

packages/adapter-node/src/env.js

@@ -0,0 +1,34 @@
+/* global ENV_PREFIX */
+
+const expected = new Set([
+	'SOCKET_PATH',
+	'HOST',
+	'PORT',
+	'ORIGIN',
+	'XFF_DEPTH',
+	'ADDRESS_HEADER',
+	'PROTOCOL_HEADER',
+	'HOST_HEADER'
+]);
+
+if (ENV_PREFIX) {
+	for (const name in process.env) {
+		if (name.startsWith(ENV_PREFIX)) {
+			const unprefixed = name.slice(ENV_PREFIX.length);
+			if (!expected.has(unprefixed)) {
+				throw new Error(
+					`You should change envPrefix (${ENV_PREFIX}) to avoid conflicts with existing environment variables — unexpectedly saw ${name}`
+				);
+			}
+		}
+	}
+}
+
+/**
+ * @param {string} name
+ * @param {any} fallback
+ */
+export function env(name, fallback) {
+	const prefixed = ENV_PREFIX + name;
+	return prefixed in process.env ? process.env[prefixed] : fallback;
+}

packages/adapter-node/src/handler.js

@@ -6,16 +6,17 @@ import { fileURLToPath } from 'url';
 import { getRequest, setResponse } from '@sveltejs/kit/node';
 import { Server } from 'SERVER';
 import { manifest } from 'MANIFEST';
+import { env } from './env.js';
 
-/* global ORIGIN, ADDRESS_HEADER, PROTOCOL_HEADER, HOST_HEADER, XFF_DEPTH_ENV */
+/* global ENV_PREFIX */
 
 const server = new Server(manifest);
-const origin = ORIGIN;
-const xff_depth = XFF_DEPTH_ENV ? parseInt(process.env[XFF_DEPTH_ENV]) : 1;
+const origin = env('ORIGIN', undefined);
+const xff_depth = parseInt(env('XFF_DEPTH', '1'));
 
-const address_header = ADDRESS_HEADER && (process.env[ADDRESS_HEADER] || '').toLowerCase();
-const protocol_header = PROTOCOL_HEADER && process.env[PROTOCOL_HEADER];
-const host_header = (HOST_HEADER && process.env[HOST_HEADER]) || 'host';
+const address_header = env('ADDRESS_HEADER', '').toLowerCase();
+const protocol_header = env('PROTOCOL_HEADER', '').toLowerCase();
+const host_header = env('HOST_HEADER', 'host').toLowerCase();
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
@@ -51,7 +52,9 @@ const ssr = async (req, res) => {
 
 	if (address_header && !(address_header in req.headers)) {
 		throw new Error(
-			`Address header was specified with ${ADDRESS_HEADER}=${process.env[ADDRESS_HEADER]} but is absent from request`
+			`Address header was specified with ${
+				ENV_PREFIX + 'ADDRESS_HEADER'
+			}=${address_header} but is absent from request`
 		);
 	}
 
@@ -66,12 +69,14 @@ const ssr = async (req, res) => {
 						const addresses = value.split(',');
 
 						if (xff_depth < 1) {
-							throw new Error(`${XFF_DEPTH_ENV} must be a positive integer`);
+							throw new Error(`${ENV_PREFIX + 'XFF_DEPTH'} must be a positive integer`);
 						}
 
 						if (xff_depth > addresses.length) {
 							throw new Error(
-								`${XFF_DEPTH_ENV} is ${xff_depth}, but only found ${addresses.length} addresses`
+								`${ENV_PREFIX + 'XFF_DEPTH'} is ${xff_depth}, but only found ${
+									addresses.length
+								} addresses`
 							);
 						}
 						return addresses[addresses.length - xff_depth].trim();

packages/adapter-node/src/index.js

@@ -1,12 +1,11 @@
 import { handler } from './handler.js';
+import { env } from './env.js';
 import compression from 'compression';
 import polka from 'polka';
 
-/* global PATH_ENV, HOST_ENV, PORT_ENV */
-
-export const path = process.env[PATH_ENV] || false;
-export const host = process.env[HOST_ENV] || '0.0.0.0';
-export const port = process.env[PORT_ENV] || (!path && '3000');
+export const path = env('SOCKET_PATH', false);
+export const host = env('HOST', '0.0.0.0');
+export const port = env('PORT', !path && '3000');
 
 const server = polka().use(
 	// https://github.com/lukeed/polka/issues/173