AWS Certified Developer Associate Flashcards (DVA-C02)

1
# Synchronous invoke via CLI
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aws lambda invoke \
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  --function-name myFunction \
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  --payload '{"key":"value"}' \
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  response.json

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import os
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DB_HOST = os.environ['DB_HOST']
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API_KEY = os.environ['API_KEY']

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def handler(event, context):
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    print(context.function_name)
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    print(context.get_remaining_time_in_millis())
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    return {"statusCode": 200, "body": "OK"}

1
# Lambda ARN using stage variable
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arn:aws:lambda:us-east-1:123:function:myFunc:${stageVariables.lambdaAlias}

1
import boto3
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s3 = boto3.client('s3')
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url = s3.generate_presigned_url(
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    'get_object',
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    Params={'Bucket': 'mybucket', 'Key': 'file.txt'},
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    ExpiresIn=3600
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)

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# boto3 automatically uses the Lambda execution role
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import boto3
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s3 = boto3.client('s3')
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s3.list_buckets()

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sts = boto3.client('sts')
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response = sts.assume_role(
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    RoleArn='arn:aws:iam::123456789:role/MyRole',
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    RoleSessionName='MySession'
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)
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creds = response['Credentials']

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kms = boto3.client('kms')
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response = kms.generate_data_key(
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    KeyId='alias/mykey',
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    KeySpec='AES_256'
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)
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plaintext_key = response['Plaintext']
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encrypted_key = response['CiphertextBlob']

1
client = boto3.client('secretsmanager')
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secret = client.get_secret_value(SecretId='prod/db/password')
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password = secret['SecretString']

1
ssm = boto3.client('ssm')
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param = ssm.get_parameter(
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    Name='/myapp/db/password',
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    WithDecryption=True
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)
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value = param['Parameter']['Value']

1
# S3 CORS config
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[{"AllowedOrigins": ["https://myapp.com"],
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  "AllowedMethods": ["GET","PUT"],
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  "AllowedHeaders": ["*"]}]

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version: 0.0
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os: linux
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files:
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  - source: /
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    destination: /var/www/html
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hooks:
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  AfterInstall:
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    - location: scripts/install_deps.sh
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  ApplicationStart:
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    - location: scripts/start_server.sh

1
# Stack A export
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Outputs:
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  VpcId:
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    Value: !Ref MyVPC
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    Export:
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      Name: MyVPC-ID
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# Stack B import
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Resources:
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  MyInstance:
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    Properties:
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      VpcId: !ImportValue MyVPC-ID

1
# SAM canary deployment
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AutoPublishAlias: live
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DeploymentPreference:
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  Type: Canary10Percent10Minutes

1
# Python instrument boto3 with X-Ray
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from aws_xray_sdk.core import xray_recorder, patch_all
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patch_all()  # patches boto3, requests, etc.

1
import time, random
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for attempt in range(5):
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    try:
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        response = call_aws_api()
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        break
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    except ThrottlingException:
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        time.sleep((2 ** attempt) + random.random())

1
# Find Lambda errors in the last hour
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fields @timestamp, @message
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| filter @message like /ERROR/
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| sort @timestamp desc
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| limit 50

1
$ aws configure
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AWS Access Key ID: AKIA...
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AWS Secret Access Key: ****
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Default region name: us-east-1
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Default output format: json

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$ aws configure --profile dev
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$ aws s3 ls --profile dev
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$ export AWS_PROFILE=dev

1
$ aws ec2 describe-instances \
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    --query 'Reservations[*].Instances[*].InstanceId' \
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    --output text

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import boto3
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from botocore.config import Config
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config = Config(
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    retries={'max_attempts': 10, 'mode': 'standard'}
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)
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client = boto3.client('dynamodb', config=config)

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paginator = boto3.client('s3').get_paginator('list_objects_v2')
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for page in paginator.paginate(Bucket='mybucket'):
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    for obj in page['Contents']:
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        print(obj['Key'])

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ec2 = boto3.client('ec2')
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waiter = ec2.get_waiter('instance_running')
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waiter.wait(InstanceIds=['i-1234567890abcdef0'])
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print("Instance is running!")

1
# LocalStack local testing
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s3 = boto3.client(
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    's3',
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    region_name='us-east-1',
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    endpoint_url='http://localhost:4566'
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)

1
import { DynamoDBClient, GetItemCommand } from "@aws-sdk/client-dynamodb";
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const client = new DynamoDBClient({ region: "us-east-1" });
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const response = await client.send(
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  new GetItemCommand({ TableName: "Users", Key: { id: { S: "123" } } })
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);

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// SDK v3 with lib-dynamodb
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import { DynamoDBDocumentClient, GetCommand } from "@aws-sdk/lib-dynamodb";
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const docClient = DynamoDBDocumentClient.from(client);
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const result = await docClient.send(
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  new GetCommand({ TableName: "Users", Key: { id: "123" } })
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);

1
try:
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    table.get_item(Key={'id': '123'})
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except ClientError as e:
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    code = e.response['Error']['Code']
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    if code == 'ProvisionedThroughputExceededException':
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        time.sleep(2)

1
$ aws cloudformation deploy \
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    --template-file template.yaml \
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    --stack-name my-app \
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    --capabilities CAPABILITY_IAM \
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    --parameter-overrides Env=prod

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from aws_cdk import Stack, aws_lambda as _lambda
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class MyStack(Stack):
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    def __init__(self, scope, id, **kwargs):
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        super().__init__(scope, id, **kwargs)
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        _lambda.Function(self, "MyFunc",
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            runtime=_lambda.Runtime.PYTHON_3_11,
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            handler="app.handler",
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            code=_lambda.Code.from_asset("lambda"))

1
# boto3 handles multipart automatically with transfer config
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from boto3.s3.transfer import TransferConfig
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config = TransferConfig(multipart_threshold=1024*25)
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s3.upload_file('largefile.zip', 'mybucket', 'largefile.zip',
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               Config=config)

1
table.put_item(
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    Item={'id': '123', 'version': 1, 'name': 'Ali'},
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    ConditionExpression='attribute_not_exists(id)'
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)
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# Fails if item with id=123 already exists