Mastering AWS CLI

AWS CLI v2 Quick Reference

A unified tool to manage AWS services from the terminal. This guide focuses on CLI v2 features, practical examples, and advanced patterns for experienced developers.

Quick Start

# Verify installation and version
aws --version

# Interactive configuration
aws configure                    # Access keys + region + output format
aws configure sso               # IAM Identity Center (SSO) - recommended

# Verify identity
aws sts get-caller-identity     # Shows Account, UserId, ARN

# Enable auto-prompt for command discovery
aws dynamodb --cli-auto-prompt

Power User Tips

# See all waiter commands for a service
aws ec2 wait help

# Generate command skeleton (fill in the blanks)
aws lambda create-function --generate-cli-skeleton > create-fn.json

# Create CLI alias for common commands
aws configure set cli_alias.whoami "sts get-caller-identity"
aws whoami  # Now works!

# Disable pager for scripting
export AWS_PAGER=""

See Advanced Patterns for JMESPath mastery and automation tricks.

Global Options

Decision Trees

Compute & Containers

Need compute?
├── Serverless functions ────────────► Lambda (references/lambda.md)
├── Docker containers
│   ├── Managed orchestration ───────► ECS (references/ecs.md)
│   ├── Kubernetes ──────────────────► EKS (references/eks.md)
│   └── Container registry ──────────► ECR (references/ecr.md)
└── Virtual machines ────────────────► EC2 (use aws ec2 commands)

Data & Storage

Need data storage?
├── Object/blob storage ─────────────► S3 (references/s3.md)
├── NoSQL (key-value/document) ──────► DynamoDB (references/dynamodb.md)
├── Relational SQL ──────────────────► Aurora/RDS (references/aurora.md)
├── Data catalog & ETL ──────────────► Glue (references/glue.md)
└── Data warehouse ──────────────────► Redshift (aws redshift commands)

Streaming & Messaging

Need streaming/messaging?
├── Kafka-compatible ────────────────► MSK (references/msk.md)
├── Real-time streams ───────────────► Kinesis (references/kinesis.md)
├── Message queues ──────────────────► SQS (aws sqs commands)
└── Pub/Sub notifications ───────────► SNS (aws sns commands)

Security & Access

Need security/access management?
├── Users, roles, policies ──────────► IAM (references/iam-security.md)
├── Secrets & credentials ───────────► Secrets Manager/SSM (references/private-parameters.md)
├── Private network access ──────────► VPC (references/vpc-networking.md)
└── Secure tunneling ────────────────► SSM/Bastion (references/bastion-tunneling.md)

Reference File Navigation

Environment Variables

Credential Precedence

The CLI resolves credentials in this order (first match wins):

1. Command-line options (--profile, explicit credentials)
2. Environment variables (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY)
3. Web identity token (EKS IRSA, OIDC)
4. SSO credentials (IAM Identity Center)
5. Credentials file (~/.aws/credentials)
6. Config file (~/.aws/config with credential_process)
7. Container credentials (ECS task role)
8. Instance metadata (EC2 instance profile, IMDSv2)

Common Patterns

Profile Switching

# Use specific profile for one command
aws s3 ls --profile production

# Set default profile for session
export AWS_PROFILE=production

# List configured profiles
aws configure list-profiles

Output Filtering with JMESPath

# Get specific fields
aws ec2 describe-instances \
    --query 'Reservations[*].Instances[*].[InstanceId,State.Name]' \
    --output table

# Filter running instances
aws ec2 describe-instances \
    --query 'Reservations[*].Instances[?State.Name==`running`].InstanceId' \
    --output text

Wait for Resource State

# Wait for instance to be running
aws ec2 wait instance-running --instance-ids i-1234567890abcdef0

# Wait for Lambda function update
aws lambda wait function-updated --function-name my-function

Best Practices

Common Errors Quick Reference

For detailed troubleshooting, see Setup.

When Not to Use

• AWS SDK code — For boto3, AWS SDK for JavaScript, etc., use programming documentation
• CloudFormation/Terraform — This skill covers CLI commands, not IaC templates
• Console UI steps — CLI-focused; use AWS documentation for console walkthroughs
• Pricing/billing — Use AWS pricing calculator or Cost Explorer documentation

Quick Command Reference

# Identity & Access
aws sts get-caller-identity
# → {"Account": "123456789012", "UserId": "AIDAEXAMPLE", "Arn": "arn:aws:iam::123456789012:user/dev"}

aws sts assume-role --role-arn arn:aws:iam::123456789012:role/Admin --role-session-name mysession
# → {"Credentials": {"AccessKeyId": "ASIA...", "SecretAccessKey": "...", "SessionToken": "..."}}

# S3
aws s3 ls
# → 2024-01-15 bucket-name-1
# → 2024-02-20 bucket-name-2

aws s3 sync ./local s3://bucket/prefix --delete

# Lambda
aws lambda invoke --function-name fn response.json
# → {"StatusCode": 200, "ExecutedVersion": "$LATEST"}

aws lambda update-function-code --function-name fn --zip-file fileb://code.zip
# → {"FunctionName": "fn", "LastModified": "2024-12-28T...", "State": "Active"}

# ECS
aws ecs list-clusters
# → {"clusterArns": ["arn:aws:ecs:us-east-1:123456789012:cluster/prod"]}

aws ecs update-service --cluster prod --service api --force-new-deployment

# EKS
aws eks update-kubeconfig --name my-cluster
# → Added new context arn:aws:eks:us-east-1:123456789012:cluster/my-cluster

aws eks list-clusters
# → {"clusters": ["my-cluster", "dev-cluster"]}

# Secrets
aws secretsmanager get-secret-value --secret-id prod/api/key --query SecretString --output text
# → sk_live_xxxxxxxxxxxxx

aws ssm get-parameter --name /app/prod/db/host --with-decryption --query Parameter.Value --output text
# → db.example.com

# Debugging
aws ssm start-session --target i-0123456789abcdef0
# → Starting session with SessionId: user-0a1b2c3d4e5f67890