Deploy Cloud Function via Serverless

今天才正式有時間來試著將cloud function推上到google cloud function。而本來認為用serverless可以省去不少時間，但不盡如此，故特地將過程記錄下來。

一開始最直覺的想法是到serverless官網上看有沒有範例，但在官網上利用filter的方式找GCP配合golang，會找不到任何範例。本想說那就找AWS配合golang，最找GCP配合nodejs，再折衷的把二個範例裡的部份內容抽出來，進行組合和運用。所幸在example裡找到了二年沒有更新的範例。就想直接將這個範例放到專案裡進行佈吏署的試驗，若是可以也就不用自行在那組合、折解、合併。不過沒想到這中間有一些文件沒有特別更新到的說明部份，讓整個deploy花了不少時間。

先來看原始的碼中放的serverless.yml和搭配範例的另一份文件，文件算是很詳細，主要就二部份要處理，一個是開啓API，另一個則是創立service account後給權限。

service: golang-simple-http-endpoint

frameworkVersion: ">=1.33.0 <2.0.0"

package:
  exclude:
    - node_modules/**
    - .gitignore
    - .git/**

plugins:
  - serverless-google-cloudfunctions

# The GCF credentials can be a little tricky to set up. Luckily we've documented this for you here:
# https://serverless.com/framework/docs/providers/google/guide/credentials/
#
# NOTE: the golang runtime is currently in alpha state, you must have access from google to use the alpha toolchain
provider:
  name: google
  runtime: go111                           # currently both vendored and go.mod repos are supported
  project: sborza-91                    # replace with your project name here
  credentials: ~/.gcloud/slsframework.json # path must be absolute, change to whichever keyfile you need

functions:
  hello:
    handler: Hello
    events:
      - http: path

為了要佈署而產生的一份Dockerfile，這份是依照其README.md的步驟寫的

# FROM node:latest

COPY . /app

WORKDIR /app

RUN npm install -g serverless

RUN serverless deploy -v

但執行時首先會碰到的問題是serverless版本，現在已經是2.1.x版了，所以要更新那。project不用說，肯定是要更新成目前GCP的project id。而runtime，從這份文件可以知道目前已到了1.13版，所以可以換成go113。那份slsframework.json就是service account產生出的json檔。

不過若是直接執行還是會有錯。參考了這二個討論，知道了是少了npmc install安裝相依性。

• Serverless plugin "serverless-google-cloudfunctions" not found. Make sure it's installed and listed in the "plugins" section of yourserverless config file.
• Serverless: Configuration error: Unrecognized provider 'google'

但修正完後還是會看到"cloudfunctions.v1beta2.function相關的錯誤訊息。找了一大堆的討論和文章，終於找到了，原來是serverless-google-cloudfunctions版本太舊

• Function does not exist error
• ServerlessError: Access Denied but no errors on CloudFormation events
• Permission error when using serverless deploy
• Migrate to CloudFunctions v1 API.
• Failed to Update the Existing Cloud Function through v2.4.2
• Migration Reference from v2 to v3
• Cloud Functions API Migration Guide

更新package.json到拿取最新的版本即可

"dependencies": {
  "serverless-google-cloudfunctions": "*"
}

調整之後可以用

serverless deploy

將範例的cloud function推上去。但使用

serverless logs --function hello

• AccessDeniedException: Caller does not have permissions to create a Service Linked Role

還是會得到

Error: The caller does not have permission

的訊息。只好先撇開這個錯誤，先往下試再加入一個範例，否可以正常的推上去。而這個範例就是Auth Trigger的cloud function。不過在serverless官方的網站上只看到pub sub event的範例，沒有auth的，而在討論裡也只有看到cloud storage的trigger寫法，當下並不清楚如果是auth event要怎麼寫。

還好找gcp官方文件裡可以看到

• Firebase Authentication Triggers
• Google Cloud Pub/Sub Triggers
• Google Cloud Storage Triggers

Pub/Sub

文件裡的這一段話很讓人在意，

The gcloud command below deploys a function that is triggered by legacy Pub/Sub notifications on a specific topic. These notifications are supported for legacy functions already consuming these events. However, we recommend using the --trigger-topic flag instead, as the legacy notifications might be removed at a future date.

gcloud functions deploy FUNCTION_NAME \
--trigger-resource TOPIC_NAME \
--trigger-event providers/cloud.pubsub/eventTypes/topic.publish \
FLAGS...

回看到serverless的文件，好像就是之前版本的用法，至於新的用法是可行的嗎？

利用serverless放到firebase後，原先的http function是不會有問題的，但auth則呈現出錯誤的圖示

"status": {
    "code": 3,
    "message": "Build failed: # serverless_function_app/main\nsrc/serverless_function_app/main/main.go:24:43: cannot refer to unexported name hello.helloAuth\nsrc/serverless_function_app/main/main.go:24:43: undefined: hello.helloAuth\nsrc/serverless_function_app/main/main.go:26:44: cannot refer to unexported name hello.helloAuth\nsrc/serverless_function_app/main/main.go:26:44: undefined: hello.helloAuth; Error ID: 6191efcd"
}

看樣子，只是一個大小寫的新手錯誤。順利的話，就可以開始進行撰寫實際行為的工作了。