feat: allow --watch to accept optional directory or list of directories

README.md

@@ -163,7 +163,7 @@ You can pass the following options via CLI arguments. You can also use `--config
 | Set the inspector port (default: 9320)                                                                                                  | `-I`          | `--debug-port`     | `FASTIFY_DEBUG_PORT`     |
 | Set the inspector host to listen on (default: loopback address or `0.0.0.0` inside Docker or Kubernetes)                                              |               | `--debug-host`     | `FASTIFY_DEBUG_HOST`     |
 | Prints pretty logs                                                                                                                      | `-P`          | `--pretty-logs`    | `FASTIFY_PRETTY_LOGS`    |
-| Watch process.cwd() directory for changes, recursively; when that happens, the process will auto reload                                 | `-w`          | `--watch`          | `FASTIFY_WATCH`          |
+| Watch for changes and auto reload. Optional dir(s) (e.g. `--watch api`) limit watch to those; default process.cwd(). | `-w`          | `--watch`          | `FASTIFY_WATCH`          |
 | Ignore changes to the specified files or directories when watch is enabled. (e.g. `--ignore-watch='node_modules .git logs/error.log'` ) |               | `--ignore-watch`   | `FASTIFY_IGNORE_WATCH`   |
 | Prints events triggered by watch listener (useful to debug unexpected reload when using `--watch` )                                     |     `-V`          | `--verbose-watch`  | `FASTIFY_VERBOSE_WATCH`   |
 | Use custom options                                                                                                                      | `-o`          | `--options`        | `FASTIFY_OPTIONS`        |

args.js

@@ -28,8 +28,8 @@ module.exports = function parseArgs (args) {
       'populate--': true
     },
     number: ['port', 'inspect-port', 'body-limit', 'plugin-timeout', 'close-grace-delay', 'trust-proxy-hop'],
-    string: ['log-level', 'address', 'socket', 'prefix', 'ignore-watch', 'logging-module', 'debug-host', 'lang', 'require', 'import', 'config', 'method', 'trust-proxy-ips'],
-    boolean: ['pretty-logs', 'options', 'watch', 'verbose-watch', 'debug', 'standardlint', 'common-prefix', 'include-hooks', 'trust-proxy-enabled'],
+    string: ['log-level', 'address', 'socket', 'prefix', 'ignore-watch', 'logging-module', 'debug-host', 'lang', 'require', 'import', 'config', 'method', 'trust-proxy-ips', 'watch'],
+    boolean: ['pretty-logs', 'options', 'verbose-watch', 'debug', 'standardlint', 'common-prefix', 'include-hooks', 'trust-proxy-enabled'],
     envPrefix: 'FASTIFY_',
     alias: {
       port: ['p'],
@@ -73,6 +73,21 @@ module.exports = function parseArgs (args) {
     : parsedArgs.trustProxyEnabled === true || parsedArgs.trustProxyEnabled === 'true'
   const trustProxy = trustProxyEnabled || parsedArgs.trustProxyIps || parsedArgs.trustProxyHop
 
+  const watchRequested = (parsedArgs.watch !== undefined && parsedArgs.watch !== false &&
+    (parsedArgs.watch === true || parsedArgs.watch === 'true' || parsedArgs.watch === '')) ||
+    args.includes('-w') || args.includes('--watch')
+  let watch = false
+  let watchPaths
+  if (watchRequested) {
+    watch = true
+    const watchVal = parsedArgs.watch
+    if (typeof watchVal === 'string' && watchVal !== '' && watchVal !== 'true') {
+      watchPaths = watchVal.split(/\s+/).map((s) => s.trim()).filter(Boolean)
+    } else {
+      watchPaths = []
+    }
+  }
+
   return {
     _: parsedArgs._,
     '--': additionalArgs,
@@ -83,7 +98,8 @@ module.exports = function parseArgs (args) {
     pluginOptions,
     prettyLogs: parsedArgs.prettyLogs,
     options: parsedArgs.options,
-    watch: parsedArgs.watch,
+    watch,
+    watchPaths,
     debug: parsedArgs.debug,
     debugPort: parsedArgs.debugPort,
     debugHost: parsedArgs.debugHost,

help/start.txt

@@ -38,9 +38,9 @@ OPTS
   [env: FASTIFY_OPTIONS]
       Use custom options
 
-  -w, --watch
+  -w, --watch [dirs...]
   [env: FASTIFY_WATCH]
-      Watch process.cwd() directory for changes, recursively; when that happens, the process will auto reload.
+      Watch for file changes and auto reload. With no value, watches process.cwd(); pass dir(s) (e.g. --watch api) to watch only those.
 
   -x, --prefix
   [env: FASTIFY_PREFIX]
@@ -74,3 +74,7 @@ Examples:
   start plugin.js passing custom options to it
 
     fastify start plugin.js -- --custom-plugin-option-1 --custom-plugin-option-2
+
+  watch only the api directory
+
+    fastify start --watch api api/server.js

lib/watch/index.js

@@ -11,7 +11,7 @@ const chokidar = require('chokidar')
 const { loadEnvQuitely } = require('../../env-loader.js')
 const forkPath = path.join(__dirname, './fork.js')
 
-const watch = function (args, ignoreWatch, verboseWatch) {
+const watch = function (args, ignoreWatch, verboseWatch, watchPaths = null) {
   const emitter = new EventEmitter()
   let allStop = false
   let childs = []
@@ -80,7 +80,10 @@ const watch = function (args, ignoreWatch, verboseWatch) {
   const ignoredArr = ignoreWatch.split(' ').map((item) => item.trim()).filter((item) => item.length)
   const ignoredPattern = arrayToRegExp(ignoredArr)
 
-  const watcher = chokidar.watch(process.cwd(), { ignored: ignoredPattern })
+  const watchTargets = (watchPaths && watchPaths.length > 0)
+    ? watchPaths.map((dir) => path.resolve(process.cwd(), dir))
+    : [process.cwd()]
+  const watcher = chokidar.watch(watchTargets, { ignored: ignoredPattern })
   watcher.on('ready', function () {
     watcher.on('all', function (event, filepath) {
       if (verboseWatch) {

start.js

@@ -52,7 +52,7 @@ async function start (args) {
   loadModules(opts)
 
   if (opts.watch) {
-    return watch(args, opts.ignoreWatch, opts.verboseWatch)
+    return watch(args, opts.ignoreWatch, opts.verboseWatch, opts.watchPaths)
   }
 
   return runFastify(args)

test/args.test.js

@@ -37,6 +37,7 @@ test('should parse args correctly', t => {
     prettyLogs: true,
     options: true,
     watch: true,
+    watchPaths: [],
     ignoreWatch: 'node_modules build dist .git bower_components logs .swp .nyc_output ignoreme.js',
     verboseWatch: true,
     port: 7777,
@@ -96,6 +97,7 @@ test('should parse args with = assignment correctly', t => {
     prettyLogs: true,
     options: true,
     watch: true,
+    watchPaths: [],
     ignoreWatch: 'node_modules build dist .git bower_components logs .swp .nyc_output ignoreme.js',
     verboseWatch: true,
     port: 7777,
@@ -175,6 +177,7 @@ test('should parse env vars correctly', t => {
     prettyLogs: true,
     options: true,
     watch: true,
+    watchPaths: [],
     ignoreWatch: 'node_modules build dist .git bower_components logs .swp .nyc_output ignoreme.js',
     verboseWatch: true,
     address: 'fastify.dev:9999',
@@ -201,7 +204,7 @@ test('should parse env vars correctly', t => {
 })
 
 test('should respect default values', t => {
-  t.plan(14)
+  t.plan(15)
 
   const argv = [
     'app.js'
@@ -213,6 +216,7 @@ test('should respect default values', t => {
   t.assert.equal(parsedArgs.options, false)
   t.assert.equal(parsedArgs.prettyLogs, false)
   t.assert.equal(parsedArgs.watch, false)
+  t.assert.equal(parsedArgs.watchPaths, undefined)
   t.assert.equal(parsedArgs.ignoreWatch, 'node_modules build dist .git bower_components logs .swp .nyc_output')
   t.assert.equal(parsedArgs.verboseWatch, false)
   t.assert.equal(parsedArgs.logLevel, 'fatal')
@@ -265,6 +269,7 @@ test('should parse custom plugin options', t => {
     prettyLogs: true,
     options: true,
     watch: true,
+    watchPaths: [],
     ignoreWatch: 'node_modules build dist .git bower_components logs .swp .nyc_output ignoreme.js',
     verboseWatch: true,
     port: 7777,
@@ -315,6 +320,7 @@ test('should parse config file correctly and prefer config values over default o
     prettyLogs: true,
     options: false,
     watch: true,
+    watchPaths: [],
     debug: false,
     debugPort: 4000,
     debugHost: '1.1.1.1',
@@ -359,6 +365,7 @@ test('should prefer command line args over config file options', t => {
     prettyLogs: true,
     options: false,
     watch: true,
+    watchPaths: [],
     debug: false,
     debugPort: 9320,
     debugHost: '1.1.1.1',
@@ -405,6 +412,7 @@ test('should favor trust proxy enabled over trust proxy ips and trust proxy hop'
     prettyLogs: false,
     options: false,
     watch: false,
+    watchPaths: undefined,
     debug: false,
     debugPort: 1111,
     debugHost: '1.1.1.1',
@@ -425,6 +433,29 @@ test('should favor trust proxy enabled over trust proxy ips and trust proxy hop'
   })
 })
 
+test('should parse --watch with single directory', t => {
+  t.plan(4)
+
+  const argv = ['--watch', 'api', 'api/server.js']
+  const parsedArgs = parseArgs(argv)
+
+  t.assert.deepStrictEqual(parsedArgs._, ['api/server.js'])
+  t.assert.equal(parsedArgs.watch, true)
+  t.assert.deepStrictEqual(parsedArgs.watchPaths, ['api'])
+  t.assert.equal(parsedArgs.ignoreWatch, 'node_modules build dist .git bower_components logs .swp .nyc_output')
+})
+
+test('should parse --watch with multiple space-separated directories', t => {
+  t.plan(3)
+
+  const argv = ['--watch', 'api lib', 'server.js']
+  const parsedArgs = parseArgs(argv)
+
+  t.assert.equal(parsedArgs.watch, true)
+  t.assert.deepStrictEqual(parsedArgs.watchPaths, ['api', 'lib'])
+  t.assert.deepStrictEqual(parsedArgs._[0], 'server.js')
+})
+
 test('should favor trust proxy ips over trust proxy hop', t => {
   t.plan(1)
 
@@ -450,6 +481,7 @@ test('should favor trust proxy ips over trust proxy hop', t => {
     prettyLogs: false,
     options: false,
     watch: false,
+    watchPaths: undefined,
     debug: false,
     debugPort: 1111,
     debugHost: '1.1.1.1',

test/watch.test.js

@@ -1,6 +1,8 @@
 'use strict'
 
+const path = require('node:path')
 const { arrayToRegExp } = require('../lib/watch/utils')
+const watch = require('../lib/watch')
 
 const { test } = require('node:test')
 
@@ -12,3 +14,15 @@ test('should equal expect RegExp', t => {
 
   t.assert.deepStrictEqual(regExp, expectRegExp)
 })
+
+test('should return emitter when called with watchPaths', t => {
+  t.plan(2)
+
+  const pluginPath = path.join(__dirname, 'plugindir', 'plugin.js')
+  const emitter = watch([pluginPath], 'node_modules', false, ['lib'])
+
+  t.assert.equal(typeof emitter.stop, 'function')
+  t.assert.equal(typeof emitter.on, 'function')
+
+  emitter.stop()
+})