環境変数とレイヤー
環境変数と、共有コードに利用するLambda Layersを使って、設定と依存関係を効率的に管理します。
「環境変数とレイヤー」はCoddyKit上の無料Serverless Backend with AWS Lambda & API Gatewayレッスンです。 これはレッスン2/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはServerless Backend with AWS Lambda & API Gateway学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Serverless Backend with AWS Lambda & API Gatewayコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
Configuring Lambda Functions
When building serverless applications, you often need to configure your Lambda functions. This includes settings that change between development, testing, and production environments.
Think about database connection strings, API endpoints, or feature flags. Hardcoding these values is a bad practice!
What are Environment Variables?
Environment variables are key-value pairs that you define for your Lambda function. Your function's code can then access these variables at runtime.
- They provide a simple way to change your function's behavior without modifying its code.
- Each function has its own set of environment variables.
Setting Environment Variables
You can set environment variables directly in the AWS Management Console when configuring your Lambda function. They can also be defined using Infrastructure as Code tools like AWS SAM or CloudFormation.
Important: While convenient, avoid storing sensitive information like database passwords directly in environment variables. Use AWS Secrets Manager for that!
Accessing Env Vars in Python
In Python, you can access environment variables using the os module, specifically os.environ.get(). This method allows you to provide a default value if the variable isn't set.
Try running this example:
import os
def lambda_handler(event, context):
# Get GREETING_MESSAGE env var, default to 'Hello'
greeting = os.environ.get('GREETING_MESSAGE', 'Hello')
# Get 'name' from the event, default to 'World'
name = event.get('name', 'World')
message = f"{greeting}, {name}!"
print(message)
return {
'statusCode': 200,
'body': message
}
# --- Local testing simulation ---
if __name__ == '__main__':
# Simulate setting an environment variable locally
os.environ['GREETING_MESSAGE'] = 'Hola'
# Simulate a Lambda event
test_event = {'name': 'CoddyKit User'}
print("\nRunning lambda_handler locally...")
result = lambda_handler(test_event, None)
print(f"Local Lambda response: {result}")
# Clean up simulated env var
del os.environ['GREETING_MESSAGE']
Env Var Best Practices
Using environment variables wisely can greatly improve your function's maintainability:
- Non-sensitive config: Use for API keys (for non-critical services), log levels, feature flags.
- Integration with Secrets Manager: For truly sensitive data (e.g., database credentials), store them in AWS Secrets Manager and retrieve them at runtime using your function's IAM role.
- Separate environments: Easily switch configs for dev, staging, and production.
Introducing Lambda Layers
As your serverless applications grow, you might find multiple Lambda functions needing the same libraries, dependencies, or utility code.
Lambda Layers solve this by allowing you to package and share common components across multiple functions.
Benefits of Lambda Layers
Layers offer several advantages for managing your Lambda functions:
- Smaller deployment packages: Your function code only contains your business logic, not large libraries.
- Code reusability: Share common functions, helper modules, or SDKs across many Lambdas.
- Faster deployments: Only upload your small function code, not entire dependency sets.
- Consistent dependencies: Ensure all functions use the same version of a library.
How Lambda Layers Work
When you attach a layer to a Lambda function, AWS extracts its contents into the /opt directory in the function's execution environment.
Your function code can then import modules or use binaries from this /opt directory as if they were part of its own deployment package.
Using a Shared Layer (Python)
Once a layer is attached, your Python function can simply import modules from it. For example, if your layer contains my_utilities.py at python/my_utilities.py, you can import it like any other module:
from my_utilities import format_message
import json
def lambda_handler(event, context):
user_name = event.get('name', 'Guest')
# Assuming format_message is in our layer
response_message = format_message(user_name)
return {
'statusCode': 200,
'body': json.dumps({'message': response_message})
}
This code isn't runnable on its own as the layer isn't defined here, but it shows how you'd import from it.
from my_utilities import format_message
import json
def lambda_handler(event, context):
user_name = event.get('name', 'Guest')
# Assuming format_message is in our layer
response_message = format_message(user_name)
return {
'statusCode': 200,
'body': json.dumps({'message': response_message})
}
Quick Check: Env Vars & Layers
Let's test your understanding of Lambda environment variables and layers.
Recap: Env Vars & Layers
In this lesson, we learned how to manage Lambda function configurations and dependencies effectively:
- Environment Variables: Key-value pairs for non-sensitive configuration, accessed via
os.environin Python. - Lambda Layers: Mechanisms for packaging and sharing common code, libraries, and dependencies across multiple functions.
- Layers lead to smaller deployment packages, improved reusability, and faster deployments.
Next up: Dive into logging and monitoring your Lambda functions with CloudWatch!
よくある質問
「環境変数とレイヤー」レッスンは無料ですか？
はい。「環境変数とレイヤー」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Serverless Backend with AWS Lambda & API Gatewayコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Serverless Backend with AWS Lambda & API Gatewayコースには全4レッスンが含まれています。
「環境変数とレイヤー」で何を学びますか？
環境変数と、共有コードに利用するLambda Layersを使って、設定と依存関係を効率的に管理します。 ブラウザで直接実行するハンズオンコードでServerless Backend with AWS Lambda & API Gatewayを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
Serverless Backend with AWS Lambda & API Gatewayを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのServerless Backend with AWS Lambda & API Gatewayは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン2/4です。
「環境変数とレイヤー」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このServerless Backend with AWS Lambda & API Gatewayレッスンでコードを書いて実行できますか？
はい。すべてのServerless Backend with AWS Lambda & API Gatewayレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。