Function loadEnvConfig

packages/next-env/index.ts:114–180

(
  dir: string,
  dev?: boolean,
  log: Log = console,
  forceReload = false,
  onReload?: (envFilePath: string) => void
)

}

export function loadEnvConfig(
  dir: string,
  dev?: boolean,
  log: Log = console,
  forceReload = false,
  onReload?: (envFilePath: string) => void
): {
  combinedEnv: Env
  parsedEnv: Env | undefined
  loadedEnvFiles: LoadedEnvFiles
} {
  if (!initialEnv) {
    initialEnv = Object.assign({}, process.env)
  }
  // only reload env when forceReload is specified
  if (combinedEnv && !forceReload) {
    return { combinedEnv, parsedEnv, loadedEnvFiles: cachedLoadedEnvFiles }
  }
  replaceProcessEnv(initialEnv)
  previousLoadedEnvFiles = cachedLoadedEnvFiles
  cachedLoadedEnvFiles = []

  const isTest = process.env.NODE_ENV === 'test'
  const mode = isTest ? 'test' : dev ? 'development' : 'production'
  const dotenvFiles = [
    `.env.${mode}.local`,
    // Don't include `.env.local` for `test` environment
    // since normally you expect tests to produce the same
    // results for everyone
    mode !== 'test' && `.env.local`,
    `.env.${mode}`,
    '.env',
  ].filter(Boolean) as string[]

  for (const envFile of dotenvFiles) {
    // only load .env if the user provided has an env config file
    const dotEnvPath = path.join(dir, envFile)

    try {
      const stats = fs.statSync(dotEnvPath)

      // make sure to only attempt to read files or named pipes
      if (!stats.isFile() && !stats.isFIFO()) {
        continue
      }

      const contents = fs.readFileSync(dotEnvPath, 'utf8')
      cachedLoadedEnvFiles.push({
        path: envFile,
        contents,
        env: {}, // This will be populated in processEnv
      })
    } catch (err: any) {
      if (err.code !== 'ENOENT') {
        log.error(`Failed to load env from ${envFile}`, err)
      }
    }
  }