Cloud Functions は global 変数から Function Name などを取得できる

Cloud Functions で以下のコードを実行して見ると、現在実行している関数の名前を取得できる。

console.log(global.process.env.FUNCTION_NAME) // -> createUser

他にも GCP_PROJECT, FUNCTION_MEMORY_MB, FUNCTION_TIMEOUT_SEC などが env から取得できる。実際に取得できる env は以下。

env { X_GOOGLE_CODE_LOCATION: '/user_code',
  WORKER_PORT: '8091',
  X_GOOGLE_SUPERVISOR_INTERNAL_PORT: '8081',
  X_GOOGLE_WORKER_PORT: '8091',
  FUNCTION_IDENTITY: 'hoge@appspot.gserviceaccount.com',
  X_GOOGLE_FUNCTION_REGION: 'us-central1',
  GCLOUD_PROJECT: 'hoge',
  FUNCTION_NAME: 'functionName',
  X_GOOGLE_FUNCTION_MEMORY_MB: '256',
  SUPERVISOR_HOSTNAME: '192.168.1.1',
  PATH: '/usr/local/bin:/usr/bin:/bin',
  X_GOOGLE_GCLOUD_PROJECT: 'hoge',
  FUNCTION_REGION: 'us-central1',
  PWD: '/user_code',
  FUNCTION_TRIGGER_TYPE: 'OTHER_EVENT_TRIGGER',
  FUNCTION_TIMEOUT_SEC: '60',
  X_GOOGLE_FUNCTION_TRIGGER_TYPE: 'OTHER_EVENT_TRIGGER',
  NODE_ENV: 'production',
  SHLVL: '1',
  X_GOOGLE_FUNCTION_NAME: 'functionName',
  X_GOOGLE_ENTRY_POINT: 'functionName',
  X_GOOGLE_FUNCTION_IDENTITY: 'hoge@appspot.gserviceaccount.com',
  X_GOOGLE_GCP_PROJECT: 'hoge',
  CODE_LOCATION: '/user_code',
  GCP_PROJECT: 'hoge',
  FUNCTION_MEMORY_MB: '256',
  X_GOOGLE_SUPERVISOR_HOSTNAME: '192.168.1.1',
  PORT: '8080',
  SUPERVISOR_INTERNAL_PORT: '8081',
  X_GOOGLE_FUNCTION_TIMEOUT_SEC: '60',
  ENTRY_POINT: 'payOrder',
  OLDPWD: '/var/tmp/worker/',
  _: '/usr/bin/env',
  HOME: '/tmp' }

これらを使うと、メタ的に Function Name を取得できるので、ライブラリ側で関数名を読み取ることができる。
starhoshi/fire-slack では明示的に関数名を指定しないでも勝手に Slack 通知に関数名を載せるようにした。

await Slack.send(
  { webhook: {}, ref: reference, error: Error('Invalid Request') }
)

このコードだけでこんな通知を送れる。

env 以外にもこんなのが取得できるが、使い道はなさそう。

global { global: [Circular],
  process: 
   process {
     title: '/nodejs/bin/node',
     version: 'v6.11.5',
     moduleLoadList: 
      [ 'Binding contextify',
        'Binding natives',
        'Binding config',
        'NativeModule events',
        'NativeModule util',
        'Binding uv',
        'NativeModule buffer',
        'Binding buffer',
        'Binding util',
        'NativeModule internal/util',
        'NativeModule timers',
        'Binding timer_wrap',
        'NativeModule internal/linkedlist',
        'NativeModule assert',
        'NativeModule internal/process',
        'NativeModule internal/process/warning',
        'NativeModule internal/process/next_tick',
        'NativeModule internal/process/promises',
        'NativeModule internal/process/stdio',
        'Binding constants',
        'NativeModule path',
        'NativeModule module',
        'NativeModule internal/module',
        'NativeModule vm',
        'NativeModule fs',
        'Binding fs',
        'NativeModule stream',
        'NativeModule internal/streams/legacy',
        'NativeModule _stream_readable',
        'NativeModule internal/streams/BufferList',
        'NativeModule _stream_writable',
        'NativeModule _stream_duplex',
        'NativeModule _stream_transform',
        'NativeModule _stream_passthrough',
        'Binding fs_event_wrap',
        'NativeModule domain',
        'NativeModule tty',
        'NativeModule net',
        'NativeModule internal/net',
        'Binding cares_wrap',
        'Binding tty_wrap',
        'Binding tcp_wrap',
        'Binding pipe_wrap',
        'Binding stream_wrap',
        'NativeModule http',
        'NativeModule _http_incoming',
        'NativeModule _http_common',
        'Binding http_parser',
        'NativeModule internal/freelist',
        'NativeModule _http_outgoing',
        'NativeModule _http_server',
        'NativeModule _http_agent',
        'NativeModule _http_client',
        'NativeModule url',
        'Binding icu',
        'NativeModule querystring',
        'NativeModule crypto',
        'Binding crypto',
        'NativeModule internal/streams/lazy_transform',
        'NativeModule string_decoder',
        'NativeModule console',
        'NativeModule zlib',
        'Binding zlib',
        'NativeModule cluster',
        'NativeModule dgram',
        'Binding udp_wrap',
        'NativeModule child_process',
        'Binding spawn_sync',
        'NativeModule internal/child_process',
        'Binding process_wrap',
        'NativeModule internal/socket_list',
        'NativeModule internal/cluster',
        'Binding signal_wrap',
        'NativeModule os',
        'Binding os',
        'NativeModule https',
        'NativeModule tls',
        'NativeModule _tls_common',
        'NativeModule _tls_wrap',
        'NativeModule _stream_wrap',
        'Binding js_stream',
        'Binding tls_wrap',
        'NativeModule _tls_legacy',
        'NativeModule punycode',
        'NativeModule dns',
        'NativeModule constants' ],
     versions: 
      { http_parser: '2.7.0',
        node: '6.11.5',
        v8: '5.1.281.108',
        uv: '1.11.0',
        zlib: '1.2.11',
        ares: '1.10.1-DEV',
        icu: '58.2',
        modules: '48',
        openssl: '1.0.2l' },
     arch: 'x64',
     platform: 'linux',
     release: 
      { name: 'node',
        lts: 'Boron',
        sourceUrl: 'https://nodejs.org/download/release/v6.11.5/node-v6.11.5.tar.gz',
        headersUrl: 'https://nodejs.org/download/release/v6.11.5/node-v6.11.5-headers.tar.gz' },
     argv: [ '/nodejs/bin/node', '/var/tmp/worker/worker.js' ],
     execArgv: [ '--max-old-space-size=256' ],
     env: ...