GSP067 — App Engine: Qwik Start (Python) / App Engine 快速入門（Python）

Lab ID: GSP067
Platform: Google Skills / Qwiklabs
Level: Introductory
Main Service: App Engine Standard Environment
Runtime: Python 3 / Flask
Final App Message: Hello, Cruel World!
Region Used: us-east1

1. Lab Objectives / 實驗目標

English: Deploy a simple Python Flask application to Google App Engine Standard Environment, test locally, modify the response, and deploy to production.

繁體中文： 將 Python Flask 應用程式部署至 Google App Engine Standard Environment，包含本機測試、修改回應內容與正式部署。

完成後應能：

Enable the App Engine Admin API / 啟用 App Engine Admin API
Clone the official Python sample repository / 下載官方 Python 範例程式庫
Set up a Python virtual environment / 建立 Python 虛擬環境
Test the Flask app locally on port 5000 / 在本機 port 5000 測試 Flask
Modify the app response text / 修改應用程式回應內容
Deploy with gcloud app deploy / 使用 gcloud app deploy 部署
Browse the deployed URL / 瀏覽已部署的 App Engine URL
Handle constraints/gcp.resourceLocations in Qwiklabs / 處理 Qwiklabs 區域限制政策

2. What Is App Engine? / App Engine 是什麼？

English: App Engine is Google Cloud's fully managed serverless application platform. Developers focus on application code — Google manages operating systems, VMs, web servers, load balancing, and scaling.

繁體中文： App Engine 是 Google Cloud 的全代管 serverless 應用平台。開發者只需專注於應用程式程式碼，作業系統、VM、Web 伺服器、負載平衡與擴縮由 Google 代管。

You manage / 你負責	Google manages / Google 負責
Application code	OS, VMs, patching
`app.yaml` config	Load balancing, scaling
Dependencies	Infrastructure monitoring

3. App Engine vs Other Serverless / 與其他 Serverless 比較

Service	Best for / 適用場景
App Engine	Full web apps with managed runtime / 完整 Web 應用，代管 runtime
Cloud Functions	Event-driven short tasks / 事件驅動的短任務
Cloud Run	Containerized apps, more flexibility / 容器化應用，彈性更高

4. Lab Architecture / 實驗架構

Cloud Shell
    │ git clone sample repo
    ▼
Flask Hello World app (local test :5000)
    │ modify main.py → "Hello, Cruel World!"
    ▼
gcloud app create --region=us-east1
    │
    ▼
gcloud app deploy
    │
    ▼
https://PROJECT_ID.appspot.com

5. Key Files / 重要檔案

File	Purpose / 用途
`main.py`	Flask app with route handlers / Flask 路由主程式
`requirements.txt`	Python dependencies (Flask) / Python 依賴套件
`app.yaml`	App Engine deployment config / App Engine 部署設定

Sample path / 範例路徑:

python-docs-samples/appengine/standard_python3/hello_world/

6. Step-by-Step Instructions / 操作步驟

Step 1 — Enable App Engine Admin API / 啟用 API

Console: Navigation menu → APIs & Services → Library → search App Engine Admin API → Enable

CLI:

gcloud services enable appengine.googleapis.com
gcloud services enable cloudbuild.googleapis.com
gcloud services enable storage.googleapis.com

Step 2 — Clone and set up / 下載並設定環境

git clone https://github.com/GoogleCloudPlatform/python-docs-samples.git
cd python-docs-samples/appengine/standard_python3/hello_world

sudo apt update && sudo apt install -y python3-venv python3-pip
python3 -m venv myenv
source myenv/bin/activate
pip install -r requirements.txt

Step 3 — Local test / 本機測試

flask --app main run --host=0.0.0.0 --port=5000

Verify / 驗證:

curl http://127.0.0.1:5000/
# Expected: Hello World!

Stop with Ctrl + C.

Step 4 — Modify the app / 修改應用程式

sed -i 's/Hello World!/Hello, Cruel World!/g' main.py
sed -i 's/Hello, World!/Hello, Cruel World!/g' main.py

Re-test locally / 再次本機測試:

flask --app main run --host=0.0.0.0 --port=5000
curl http://127.0.0.1:5000/
# Expected: Hello, Cruel World!

Step 5 — Create App Engine app / 建立 App Engine 應用

gcloud app create --region=us-east1

Warning / 警告: App Engine region is irreversible — it cannot be changed after creation.
App Engine 區域建立後不可更改，正式環境部署前需審慎評估。

Step 6 — Deploy / 部署

gcloud app deploy app.yaml --quiet

Expected output / 預期輸出:

Deployed service [default] to [https://PROJECT_ID.appspot.com]

Step 7 — Verify / 驗證

gcloud app browse
curl https://PROJECT_ID.appspot.com
# Expected: Hello, Cruel World!

7. Region Policy (`constraints/gcp.resourceLocations`) / 區域限制

English: Qwiklabs projects often restrict which regions you can use. Always check the effective org policy before gcloud app create.

繁體中文： Qwiklabs 專案常限制可使用的區域。執行 gcloud app create 前，務必先查詢有效的組織政策。

PROJECT_ID="$(gcloud config get-value project)"
gcloud resource-manager org-policies describe constraints/gcp.resourceLocations \
  --project="$PROJECT_ID" \
  --effective

App Engine Region	Underlying location checked / 底層檢查位置
`us-central`	`us-central1`
`europe-west`	`europe-west1`
`us-east1`	`us-east1`

Tip: Use exact region names from allowedValues, not broad values like US or us.
提示： 使用 allowedValues 中的具體 region 名稱，不要用 US、us 等寬泛值。

8. Troubleshooting / 疑難排解

Issue	Cause / 原因	Fix / 解法
`violates constraint gcp.resourceLocations`	Region not in allowedValues	Query policy, pick allowed region
`No App Engine application`	`gcloud app create` not run	Run `gcloud app create --region=VALID`
`Unable to retrieve P4SA`	Transient deploy error	Retry `gcloud app deploy --quiet`
`Regional Access Boundary` warning	Qwiklabs transient warning	Ignore if resource created successfully
Flask won't start	Wrong directory or missing venv	`cd` to app dir, `source myenv/bin/activate`

9. gcloud Quick Reference / 指令速查

# Project & region
gcloud config get-value project
gcloud config set compute/region us-east1

# App Engine
gcloud app regions list
gcloud app create --region=us-east1
gcloud app deploy app.yaml --quiet
gcloud app browse
gcloud app describe --format='value(defaultHostname)'
gcloud app logs tail -s default

10. Quiz Notes / 測驗筆記

Question	Answer
What do developers focus on with App Engine?	Application code
Supported runtimes?	Python, Java, PHP, Go, Node.js, Ruby
Similar serverless platforms?	Cloud Functions, Cloud Run

11. Summary / 總結

English: GSP067 walks through the full App Engine workflow — clone a Flask sample, test locally, modify the response, create an App Engine app, deploy, and verify. Key takeaways: app.yaml drives deployment, App Engine region is permanent, and Qwiklabs org policies may restrict region choice.

繁體中文： GSP067 涵蓋 App Engine 完整流程：複製 Flask 範例 → 本機測試 → 修改回應 → 建立 App Engine 應用 → 部署 → 驗證。重點：app.yaml 是部署核心、App Engine 區域不可更改、Qwiklabs 可能限制 region 選擇。