feat: add support to load env file

docs/reference/cli.md

@@ -181,6 +181,28 @@ tsdown --env.NODE_ENV=production
 
 Note that environment variables defined with `--env.VAR_NAME` can only be accessed as `import.meta.env.VAR_NAME` or `process.env.VAR_NAME`.
 
+## `--env-file <file>`
+
+Load environment variables from a file. When used together with `--env`, variables in `--env` take precedence.
+
+:::tip
+To prevent accidental exposure of sensitive information, only environment variables prefixed with `TSDOWN_` are injected by default. You can customize this behavior using the [`--env-prefix`](#env-prefix) flag.
+:::
+
+```bash
+tsdown --env-file .env.production
+```
+
+## `--env-prefix <prefix>` {#env-prefix}
+
+When loading environment variables from a file via `--env-file`, only include variables that start with these prefixes.
+
+- **Default:** `TSDOWN_`
+
+```bash
+tsdown --env-file .env --env-prefix APP_ --env-prefix TSDOWN_
+```
+
 ## `--debug-logs [feat]`
 
 Show debug logs.

docs/zh-CN/reference/cli.md

@@ -181,6 +181,28 @@ tsdown --env.NODE_ENV=production
 
 注意，通过 `--env.VAR_NAME` 定义的环境变量只能通过 `import.meta.env.VAR_NAME` 或 `process.env.VAR_NAME` 访问。
 
+## `--env-file <file>`
+
+从文件加载环境变量。当与 `--env` 一起使用时，`--env` 中的变量优先生效。
+
+:::tip
+为防止敏感信息意外暴露，默认仅注入以 `TSDOWN_` 前缀开头的环境变量。您可以通过 [`--env-prefix`](#env-prefix) 标志自定义此行为。
+:::
+
+```bash
+tsdown --env-file .env.production
+```
+
+## `--env-prefix <prefix>` {#env-prefix}
+
+通过 `--env-file` 加载环境变量时，仅包含以这些前缀开头的变量。
+
+- **默认值：** `TSDOWN_`
+
+```bash
+tsdown --env-file .env --env-prefix APP_ --env-prefix TSDOWN_
+```
+
 ## `--debug-logs [feat]`
 
 显示调试日志。

dts.snapshot.json

@@ -122,10 +122,10 @@
     "NoExternalFn": "type NoExternalFn = (_: string, _: string | undefined) => boolean | null | undefined | void",
     "CIOption": "type CIOption = 'ci-only' | 'local-only'",
     "WithEnabled": "type WithEnabled<T> = boolean | undefined | CIOption | (T & { enabled?: boolean | CIOption })",
-    "UserConfig": "interface UserConfig {\n entry?: TsdownInputOption\n external?: ExternalOption\n noExternal?: Arrayable<string | RegExp> | NoExternalFn\n inlineOnly?: Arrayable<string | RegExp>\n skipNodeModulesBundle?: boolean\n alias?: Record<string, string>\n tsconfig?: string | boolean\n platform?: 'node' | 'neutral' | 'browser'\n target?: string | string[] | false\n env?: Record<string, any>\n define?: Record<string, string>\n shims?: boolean\n treeshake?: boolean | TreeshakingOptions\n loader?: ModuleTypes\n removeNodeProtocol?: boolean\n nodeProtocol?: 'strip' | boolean\n plugins?: InputOptions['plugins']\n inputOptions?: InputOptions | ((_: InputOptions, _: NormalizedFormat, _: { cjsDts: boolean }) => Awaitable<InputOptions | void | null>)\n format?: Format | Format[] | Partial<Record<Format, Partial<ResolvedConfig>>>\n globalName?: string\n outDir?: string\n write?: boolean\n sourcemap?: Sourcemap\n clean?: boolean | string[]\n minify?: boolean | 'dce-only' | MinifyOptions\n footer?: ChunkAddon\n banner?: ChunkAddon\n unbundle?: boolean\n bundle?: boolean\n fixedExtension?: boolean\n outExtensions?: OutExtensionFactory\n hash?: boolean\n cjsDefault?: boolean\n outputOptions?: OutputOptions | ((_: OutputOptions, _: NormalizedFormat, _: { cjsDts: boolean }) => Awaitable<OutputOptions | void | null>)\n cwd?: string\n name?: string\n silent?: boolean\n logLevel?: LogLevel\n failOnWarn?: boolean | CIOption\n customLogger?: Logger\n fromVite?: boolean | 'vitest'\n watch?: boolean | Arrayable<string>\n ignoreWatch?: Arrayable<string | RegExp>\n debug?: WithEnabled<DebugOptions>\n onSuccess?: string | ((_: ResolvedConfig, _: AbortSignal) => void | Promise<void>)\n dts?: WithEnabled<DtsOptions>\n unused?: WithEnabled<UnusedOptions>\n publint?: WithEnabled<PublintOptions>\n attw?: WithEnabled<AttwOptions>\n report?: WithEnabled<ReportOptions>\n globImport?: boolean\n exports?: WithEnabled<ExportsOptions>\n publicDir?: CopyOptions | CopyOptionsFn\n copy?: CopyOptions | CopyOptionsFn\n hooks?: Partial<TsdownHooks> | ((_: Hookable<TsdownHooks>) => Awaitable<void>)\n workspace?: Workspace | Arrayable<string> | true\n}",
+    "UserConfig": "interface UserConfig {\n entry?: TsdownInputOption\n external?: ExternalOption\n noExternal?: Arrayable<string | RegExp> | NoExternalFn\n inlineOnly?: Arrayable<string | RegExp>\n skipNodeModulesBundle?: boolean\n alias?: Record<string, string>\n tsconfig?: string | boolean\n platform?: 'node' | 'neutral' | 'browser'\n target?: string | string[] | false\n env?: Record<string, any>\n envFile?: string\n envPrefix?: string | string[]\n define?: Record<string, string>\n shims?: boolean\n treeshake?: boolean | TreeshakingOptions\n loader?: ModuleTypes\n removeNodeProtocol?: boolean\n nodeProtocol?: 'strip' | boolean\n plugins?: InputOptions['plugins']\n inputOptions?: InputOptions | ((_: InputOptions, _: NormalizedFormat, _: { cjsDts: boolean }) => Awaitable<InputOptions | void | null>)\n format?: Format | Format[] | Partial<Record<Format, Partial<ResolvedConfig>>>\n globalName?: string\n outDir?: string\n write?: boolean\n sourcemap?: Sourcemap\n clean?: boolean | string[]\n minify?: boolean | 'dce-only' | MinifyOptions\n footer?: ChunkAddon\n banner?: ChunkAddon\n unbundle?: boolean\n bundle?: boolean\n fixedExtension?: boolean\n outExtensions?: OutExtensionFactory\n hash?: boolean\n cjsDefault?: boolean\n outputOptions?: OutputOptions | ((_: OutputOptions, _: NormalizedFormat, _: { cjsDts: boolean }) => Awaitable<OutputOptions | void | null>)\n cwd?: string\n name?: string\n silent?: boolean\n logLevel?: LogLevel\n failOnWarn?: boolean | CIOption\n customLogger?: Logger\n fromVite?: boolean | 'vitest'\n watch?: boolean | Arrayable<string>\n ignoreWatch?: Arrayable<string | RegExp>\n debug?: WithEnabled<DebugOptions>\n onSuccess?: string | ((_: ResolvedConfig, _: AbortSignal) => void | Promise<void>)\n dts?: WithEnabled<DtsOptions>\n unused?: WithEnabled<UnusedOptions>\n publint?: WithEnabled<PublintOptions>\n attw?: WithEnabled<AttwOptions>\n report?: WithEnabled<ReportOptions>\n globImport?: boolean\n exports?: WithEnabled<ExportsOptions>\n publicDir?: CopyOptions | CopyOptionsFn\n copy?: CopyOptions | CopyOptionsFn\n hooks?: Partial<TsdownHooks> | ((_: Hookable<TsdownHooks>) => Awaitable<void>)\n workspace?: Workspace | Arrayable<string> | true\n}",
     "InlineConfig": "interface InlineConfig extends UserConfig {\n config?: boolean | string\n configLoader?: 'auto' | 'native' | 'unrun'\n filter?: RegExp | Arrayable<string>\n}",
     "UserConfigFn": "type UserConfigFn = (_: InlineConfig, _: { ci: boolean }) => Awaitable<Arrayable<UserConfig>>",
     "UserConfigExport": "type UserConfigExport = Awaitable<Arrayable<UserConfig> | UserConfigFn>",
-    "ResolvedConfig": "type ResolvedConfig = Overwrite<MarkPartial<Omit<UserConfig, 'workspace' | 'fromVite' | 'publicDir' | 'silent' | 'bundle' | 'removeNodeProtocol' | 'logLevel' | 'failOnWarn' | 'customLogger'>, 'globalName' | 'inputOptions' | 'outputOptions' | 'minify' | 'define' | 'alias' | 'external' | 'onSuccess' | 'outExtensions' | 'hooks' | 'copy' | 'loader' | 'name' | 'banner' | 'footer'>, { entry: Record<string, string>; nameLabel: string | undefined; format: NormalizedFormat; target?: string[]; clean: string[]; pkg?: PackageJsonWithPath; nodeProtocol: 'strip' | boolean; logger: Logger; ignoreWatch: Array<string | RegExp>; noExternal?: NoExternalFn; inlineOnly?: Array<string | RegExp>; dts: false | DtsOptions; report: false | ReportOptions; tsconfig: false | string; exports: false | ExportsOptions; debug: false | DebugOptions; publint: false | PublintOptions; attw: false | AttwOptions; unused: false | UnusedOptions }>"
+    "ResolvedConfig": "type ResolvedConfig = Overwrite<MarkPartial<Omit<UserConfig, 'workspace' | 'fromVite' | 'publicDir' | 'silent' | 'bundle' | 'removeNodeProtocol' | 'logLevel' | 'failOnWarn' | 'customLogger' | 'envFile' | 'envPrefix'>, 'globalName' | 'inputOptions' | 'outputOptions' | 'minify' | 'define' | 'alias' | 'external' | 'onSuccess' | 'outExtensions' | 'hooks' | 'copy' | 'loader' | 'name' | 'banner' | 'footer'>, { entry: Record<string, string>; nameLabel: string | undefined; format: NormalizedFormat; target?: string[]; clean: string[]; pkg?: PackageJsonWithPath; nodeProtocol: 'strip' | boolean; logger: Logger; ignoreWatch: Array<string | RegExp>; noExternal?: NoExternalFn; inlineOnly?: Array<string | RegExp>; dts: false | DtsOptions; report: false | ReportOptions; tsconfig: false | string; exports: false | ExportsOptions; debug: false | DebugOptions; publint: false | PublintOptions; attw: false | AttwOptions; unused: false | UnusedOptions }>"
   }
 }

src/cli.ts

@@ -56,6 +56,15 @@ cli
   .option('--from-vite [vitest]', 'Reuse config from Vite or Vitest')
   .option('--report', 'Size report', { default: true })
   .option('--env.* <value>', 'Define compile-time env variables')
+  .option(
+    '--env-file <file>',
+    'Load environment variables from a file, when used together with --env, variables in --env take precedence',
+  )
+  .option(
+    '--env-prefix <prefix>',
+    'Prefix for env variables to inject into the bundle',
+    { default: 'TSDOWN_' },
+  )
   .option('--on-success <command>', 'Command to run on success')
   .option('--copy <dir>', 'Copy files to output dir')
   .option('--public-dir <dir>', 'Alias for --copy, deprecated')

src/config/options.ts

@@ -1,5 +1,7 @@
+import { readFile } from 'node:fs/promises'
 import path from 'node:path'
 import process from 'node:process'
+import { parseEnv } from 'node:util'
 import { blue } from 'ansis'
 import { createDefu } from 'defu'
 import isInCi from 'is-in-ci'
@@ -62,6 +64,8 @@ export async function resolveUserConfig(
     report = true,
     target,
     env = {},
+    envFile,
+    envPrefix = 'TSDOWN_',
     copy,
     publicDir,
     hash = true,
@@ -164,6 +168,28 @@ export async function resolveUserConfig(
     }
   }
 
+  envPrefix = toArray(envPrefix)
+  if (envPrefix.includes('')) {
+    logger.warn(
+      '`envPrefix` includes an empty string; filtering is disabled. All environment variables from the env file and process.env will be injected into the build. Ensure this is intended to avoid accidental leakage of sensitive information.',
+    )
+  }
+  const envFromProcess = filterEnv(process.env, envPrefix)
+  if (envFile) {
+    const resolvedPath = path.resolve(cwd, envFile)
+    logger.info(nameLabel, `env file: ${color(resolvedPath)}`)
+
+    const parsed = parseEnv(await readFile(resolvedPath, 'utf8'))
+    const envFromFile = filterEnv(parsed, envPrefix)
+
+    // precedence: env file < process.env < tsdown option
+    env = { ...envFromFile, ...envFromProcess, ...env }
+  } else {
+    // precedence: process.env < tsdown option
+    env = { ...envFromProcess, ...env }
+  }
+  debugLog(`Environment variables: %O`, env)
+
   if (fromVite) {
     const viteUserConfig = await loadViteConfig(
       fromVite === true ? 'vite' : fromVite,
@@ -278,6 +304,23 @@ export async function resolveUserConfig(
   })
 }
 
+/** filter env variables by prefixes */
+function filterEnv(
+  envDict: Record<string, string | undefined>,
+  envPrefixes: string[],
+) {
+  const env: Record<string, string> = {}
+  for (const [key, value] of Object.entries(envDict)) {
+    if (
+      envPrefixes.some((prefix) => key.startsWith(prefix)) &&
+      value !== undefined
+    ) {
+      env[key] = value
+    }
+  }
+  return env
+}
+
 const defu = createDefu((obj, key, value) => {
   if (Array.isArray(obj[key]) && Array.isArray(value)) {
     obj[key] = value

src/config/types.ts

@@ -208,7 +208,7 @@ export interface UserConfig {
   target?: string | string[] | false
 
   /**
-   * Compile-time env variables.
+   * Compile-time env variables, which can be accessed via `import.meta.env` or `process.env`.
    * @example
    * ```json
    * {
@@ -218,6 +218,17 @@ export interface UserConfig {
    * ```
    */
   env?: Record<string, any>
+  /**
+   * Path to env file providing compile-time env variables.
+   * @example
+   * `.env`, `.env.production`, etc.
+   */
+  envFile?: string
+  /**
+   * When loading env variables from `envFile`, only include variables with these prefixes.
+   * @default 'TSDOWN_'
+   */
+  envPrefix?: string | string[]
   define?: Record<string, string>
 
   /** @default false */
@@ -565,6 +576,8 @@ export type ResolvedConfig = Overwrite<
       | 'logLevel' // merge to `logger`
       | 'failOnWarn' // merge to `logger`
       | 'customLogger' // merge to `logger`
+      | 'envFile' // merged to `env`
+      | 'envPrefix' // merged to `env`
     >,
     | 'globalName'
     | 'inputOptions'

tests/__snapshots__/env-file-flag.snap.md

@@ -0,0 +1,12 @@
+## index.mjs
+
+```mjs
+//#region index.ts
+const foo = "bar";
+const bar = "override";
+const custom = "tsdown";
+const debug = true;
+
+//#endregion
+export { bar, custom, debug, foo };
+```

tests/__snapshots__/env-prefix-flag.snap.md

@@ -0,0 +1,11 @@
+## index.mjs
+
+```mjs
+//#region index.ts
+const foo = "foo";
+const bar = "bar";
+const custom = import.meta.env.CUSTOM;
+
+//#endregion
+export { bar, custom, foo };
+```

tests/index.test.ts

@@ -333,6 +333,67 @@ test('env flag', async (context) => {
   expect(snapshot).contains('const debug = true')
 })
 
+test('env-file flag', async (context) => {
+  const files = {
+    'index.ts': `export const foo = import.meta.env.TSDOWN_FOO
+    export const bar = import.meta.env.TSDOWN_BAR
+    export const custom = import.meta.env.CUSTOM
+    export const debug = process.env.DEBUG
+    `,
+    '.env': `TSDOWN_FOO=bar
+    TSDOWN_BAR=baz`,
+  }
+  const { snapshot } = await testBuild({
+    context,
+    files,
+    options: {
+      env: {
+        CUSTOM: 'tsdown',
+        DEBUG: true,
+        TSDOWN_BAR: 'override',
+      },
+      envFile: '.env',
+    },
+  })
+  expect(snapshot).contains('const foo = "bar"')
+  expect(snapshot).contains(
+    'const bar = "override"',
+    'Env var from --env should override .env file',
+  )
+  expect(snapshot).contains('const custom = "tsdown"')
+  expect(snapshot).contains('const debug = true')
+})
+
+test('env-prefix flag', async (context) => {
+  const files = {
+    'index.ts': `export const foo = import.meta.env.MYAPP_FOO
+    export const bar = import.meta.env.TSDOWN_BAR
+    export const custom = import.meta.env.CUSTOM
+    `,
+    '.env': `MYAPP_FOO=foo
+    TSDOWN_BAR=bar
+    `,
+  }
+  const { snapshot } = await testBuild({
+    context,
+    files,
+    options: {
+      env: {
+        MYAPP_FOO: 'foo',
+        TSDOWN_BAR: 'bar',
+      },
+      envFile: '.env',
+      envPrefix: ['MYAPP_', 'TSDOWN_'],
+    },
+  })
+  expect(snapshot).contains('const foo = "foo"')
+  expect(snapshot).contains('const bar = "bar"')
+  expect(snapshot).contains(
+    'const custom = import.meta.env.CUSTOM',
+    'Unmatched prefix env var should not be replaced',
+  )
+})
+
 test('minify', async (context) => {
   const files = { 'index.ts': `export const foo = true` }
   const { snapshot } = await testBuild({