developer things

1 EC2 instant metadata API.

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2 aws profile

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3 CLI

• aws cli with MFA. : cli written in py(boto3)
• aws sts get-session-token
• --serial-number arn-of-the-mfa-device
• --tokencode code-from-token
• --duration-seconds 3600
• --region us-east-1 (default)

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4 aws sdk

• in-built retry mechanism (with exponential backoff)
• java py node.js

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5 Aws limits

on API call.

• ec2:describeInstance - 100/s
• s3:getObject - 5500/s

on Resources

• open ticket ?
• service Quota API

Exponential backoff

• while making api call, if get ThrottlingException or 5XX intermittently, use it.
• retry:1 after 1 sec
• retry:2 after 2 sec
• retry:3 after 4 sec
• retry:4 after 8 sec

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6 AWS CLI/SDK(java) Credentials Provider Chain

• The CLI will look for credentials in this order:
• CLI option – --profile, or
• SDK :: Java system properties – aws.accessKeyId and aws.secretKey
• Environment variables – AWS_ACCESS_KEY_ID,AWS_SECRET_ACCESS_KEY,AWS_SESSION_TOKEN
• ~/.aws/credentials
• ~/.aws/config
• Container credentials – for ECS tasks
• Instance profile credentials – for EC2 Instance Profiles

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7 signV4

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• AWS SDKs and AWS CLI handle SigV4 signing automatically