feat(dev-mode): add --reflection flag (#797)

Author: Weakky

src/cli/commands/dev.ts

@@ -18,6 +18,8 @@ const DEV_ARGS = {
   '--inspect-brk': String,
   '--entrypoint': String,
   '-e': '--entrypoint',
+  '--reflection': Boolean,
+  '-r': '--reflection',
   '--help': Boolean,
   '-h': '--help',
 }
@@ -52,8 +54,16 @@ export class Dev implements Command {
 
     log.info('start', { version: ownPackage.version })
 
-    const runDebouncedReflection = simpleDebounce((layout: Layout.Layout) => {
-      return Reflection.reflect(layout, { artifacts: true })
+    const runDebouncedReflection = simpleDebounce(async (layout: Layout.Layout) => {
+      const reflectionResult = await Reflection.reflect(layout, { artifacts: true })
+      if (args['--reflection']) {
+        if (reflectionResult.success) {
+          log.info('reflection done')
+          log.info('waiting for file changes to run reflection...')
+        } else {
+          log.error('reflection failed', { error: reflectionResult.error })
+        }
+      }
     })
 
     const devPlugin: Plugin.WorktimeHooks = {
@@ -74,6 +84,10 @@ export class Dev implements Command {
             layout = await Layout.create({ entrypointPath })
           }
 
+          if (args['--reflection']) {
+            log.info('running reflection')
+          }
+
           runDebouncedReflection(layout)
         },
       },
@@ -97,8 +111,14 @@ export class Dev implements Command {
       target: ts.ScriptTarget.ES2015,
     })
 
+    /**
+     * We use an empty script when in reflection mode so that the user's app doesn't run.
+     * The watcher will keep running though and so will reflection in the devPlugin.onBeforeWatcherStartOrRestart hook above
+     */
+    const entrypointScript = args['--reflection'] ? '' : transpiledStartModule
+
     const watcher = await createWatcher({
-      entrypointScript: transpiledStartModule,
+      entrypointScript,
       sourceRoot: layout.sourceRoot,
       cwd: process.cwd(),
       plugins: [devPlugin].concat(worktimePlugins.map((p) => p.hooks)),
@@ -116,6 +136,7 @@ export class Dev implements Command {
   
         Flags:
           -e, --entrypoint    Custom entrypoint to your app (default: app.ts)
+          -r, --reflection    Run dev mode for reflection only (eg: typegen, sdl file etc..)
           -h,       --help    Show this help message
       `
   }

src/lib/watcher/runner.ts

@@ -5,18 +5,19 @@ require('../tty-linker').create().child.install()
 import { rootLogger } from '../nexus-logger'
 import hook from './hook'
 import * as IPC from './ipc'
+import * as DevMode from '../../runtime/dev-mode'
 
 const log = rootLogger.child('dev').child('runner')
 
 main()
 
 async function main() {
-  if (!process.env.ENTRYPOINT_SCRIPT) {
+  if (process.env.ENTRYPOINT_SCRIPT === undefined) {
     throw new Error('process.env.ENTRYPOINT_SCRIPT needs to be defined')
   }
 
   // Enable dev mode code paths for IPC interaction
-  process.env.NEXUS_DEV_MODE = 'true'
+  process.env[DevMode.DEV_MODE_ENV_VAR_NAME] = 'true'
 
   // TODO perhaps we should move these unhandled error/rejections
   // to start module because we probably want them just as much from production as

src/lib/watcher/watcher.ts

@@ -51,7 +51,6 @@ export async function createWatcher(options: Options): Promise<Watcher> {
       }
 
       options.events?.({ type: 'server_listening' })
-      watcher.resume()
     },
     onRunnerStdioMessage({ stdio, data }) {
       options.events?.({ type: 'runner_stdio', stdio, data })
@@ -180,22 +179,25 @@ export async function createWatcher(options: Options): Promise<Watcher> {
     }
     restarting = true
     clearConsole()
-    log.trace('hook', { name: 'beforeWatcherStartOrRestart' })
+    log.info('restarting', change)
 
+    log.trace('hook', { name: 'beforeWatcherStartOrRestart' })
     for (const plugin of plugins) {
       const runnerChanges = await plugin.dev.onBeforeWatcherStartOrRestart?.(change)
       if (runnerChanges) {
         link.updateOptions(runnerChanges)
       }
     }
+
     log.trace('hook', { name: 'beforeWatcherRestart' })
     plugins.forEach((p) => {
       p.dev.onBeforeWatcherRestart?.()
     })
-    log.info('restarting', change)
+
     options.events?.({ type: 'restart', file: change.file, reason: change.type })
     await link.startOrRestart()
     restarting = false
+    watcher.resume()
   }
 
   let resolveWatcherPromise: null | (() => void) = null

src/runtime/dev-mode.ts

@@ -15,7 +15,7 @@ import { fatal } from '../lib/process'
 /**
  * Data
  */
-const DEV_MODE_ENV_VAR_NAME = 'NEXUS_DEV_MODE'
+export const DEV_MODE_ENV_VAR_NAME = 'NEXUS_DEV_MODE'
 
 /**
  * Eager integrity check.

src/runtime/server/server.ts

@@ -6,6 +6,7 @@ import * as Net from 'net'
 import stripAnsi from 'strip-ansi'
 import * as Plugin from '../../lib/plugin'
 import { AppState } from '../app'
+import * as DevMode from '../dev-mode'
 import { ContextContributor } from '../schema/schema'
 import { log } from './logger'
 import { createRequestHandlerPlayground } from './request-handler-playground'
@@ -88,6 +89,7 @@ export function create(appState: AppState) {
           path: settings.data.path,
           playgroundPath: settings.data.playground ? settings.data.playground.path : undefined,
         })
+        DevMode.sendServerReadySignalToDevModeMaster()
       },
       async stop() {
         if (!state.running) {