Getting Started

# Set your region once -- paste this into every new terminal session
export AWS_REGION=ap-south-1

# Verify AWS CLI knows your region
aws configure get region

# List all available regions
aws ec2 describe-regions --query 'Regions[*].RegionName' --output table

# macOS (Homebrew)
brew install awscli

# Linux (apt)
sudo apt install awscli

# Verify installation
aws --version
# Expected: aws-cli/2.x.x Python/3.x.x ...

aws configure
# AWS Access Key ID: paste your key ID
# AWS Secret Access Key: paste your secret key
# Default region name: ap-south-1
# Default output format: json

# Verify it works
aws sts get-caller-identity

# Export variables so you don't retype them
export AWS_REGION=ap-south-1
export ACCOUNT_ID=$(aws sts get-caller-identity --query Account --output text)

# --query filters the JSON response (JMESPath syntax)
aws ec2 describe-instances --query 'Reservations[*].Instances[*].InstanceId'

# --output controls the format: json (default), text, table
aws s3 ls --output table

# --region overrides your configured region for one command
aws s3 ls --region us-east-1

# Billing metrics are always in us-east-1 regardless of your working region
aws cloudwatch put-metric-alarm \
  --alarm-name billing-alert-5usd \
  --alarm-description "Alert when AWS charges exceed USD 5" \
  --namespace AWS/Billing \
  --metric-name EstimatedCharges \
  --dimensions Name=Currency,Value=USD \
  --statistic Maximum \
  --period 86400 \
  --evaluation-periods 1 \
  --threshold 5 \
  --comparison-operator GreaterThanOrEqualToThreshold \
  --treat-missing-data notBreaching \
  --region us-east-1

# Create SNS topic for the alert (also in us-east-1)
BILLING_SNS=$(aws sns create-topic \
  --name billing-alerts \
  --region us-east-1 \
  --query 'TopicArn' --output text)

# Subscribe your email
aws sns subscribe \
  --topic-arn $BILLING_SNS \
  --protocol email \
  --notification-endpoint your-email@example.com \
  --region us-east-1

# Attach SNS to the alarm
aws cloudwatch put-metric-alarm \
  --alarm-name billing-alert-5usd \
  --alarm-description "Alert when AWS charges exceed USD 5" \
  --namespace AWS/Billing \
  --metric-name EstimatedCharges \
  --dimensions Name=Currency,Value=USD \
  --statistic Maximum \
  --period 86400 \
  --evaluation-periods 1 \
  --threshold 5 \
  --comparison-operator GreaterThanOrEqualToThreshold \
  --treat-missing-data notBreaching \
  --alarm-actions $BILLING_SNS \
  --region us-east-1

echo "Billing alert set. Confirm the subscription in your email."

cat > /tmp/budget.json << 'EOF'
{
  "BudgetName": "aws-learning-monthly",
  "BudgetLimit": {
    "Amount": "10",
    "Unit": "USD"
  },
  "TimeUnit": "MONTHLY",
  "BudgetType": "COST"
}
EOF

cat > /tmp/notifications.json << 'EOF'
[
  {
    "Notification": {
      "NotificationType": "ACTUAL",
      "ComparisonOperator": "GREATER_THAN",
      "Threshold": 50,
      "ThresholdType": "PERCENTAGE"
    },
    "Subscribers": [
      {"SubscriptionType": "EMAIL", "Address": "your-email@example.com"}
    ]
  },
  {
    "Notification": {
      "NotificationType": "ACTUAL",
      "ComparisonOperator": "GREATER_THAN",
      "Threshold": 80,
      "ThresholdType": "PERCENTAGE"
    },
    "Subscribers": [
      {"SubscriptionType": "EMAIL", "Address": "your-email@example.com"}
    ]
  }
]
EOF

aws budgets create-budget \
  --account-id $ACCOUNT_ID \
  --budget file:///tmp/budget.json \
  --notifications-with-subscribers file:///tmp/notifications.json

echo "Budget created: USD 10/month with alerts at 50% and 80%"

export AWS_REGION=ap-south-1

echo "=== Running EC2 Instances ==="
aws ec2 describe-instances \
  --filters Name=instance-state-name,Values=running \
  --query 'Reservations[*].Instances[*].{ID:InstanceId,Type:InstanceType,Name:Tags[?Key==`Name`].Value|[0]}' \
  --region $AWS_REGION --output table

echo "=== RDS Instances ==="
aws rds describe-db-instances \
  --query 'DBInstances[*].{ID:DBInstanceIdentifier,Class:DBInstanceClass,Status:DBInstanceStatus}' \
  --region $AWS_REGION --output table

echo "=== Elastic IPs ==="
aws ec2 describe-addresses \
  --query 'Addresses[*].{IP:PublicIp,AssociatedInstance:InstanceId}' \
  --region $AWS_REGION --output table

echo "=== NAT Gateways ==="
aws ec2 describe-nat-gateways \
  --filter Name=state,Values=available \
  --query 'NatGateways[*].{ID:NatGatewayId,State:State}' \
  --region $AWS_REGION --output table

echo "=== S3 Buckets ==="
aws s3 ls

# See your current identity
aws sts get-caller-identity

# List policies attached to your IAM user
aws iam list-attached-user-policies --user-name aws-learning-admin

# See what a policy allows (example: AWSLambdaBasicExecutionRole)
aws iam get-policy-version \
  --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole \
  --version-id v1 \
  --query 'PolicyVersion.Document'

# 1. AWS CLI (already installed in Part 3)
aws --version

# 2. jq -- JSON processor, used in every lab to parse CLI output
brew install jq          # macOS
sudo apt install jq      # Ubuntu/Debian

jq --version

# 3. Python 3 -- used in a few labs for quick calculations
python3 --version

# 4. zip -- needed for packaging Lambda functions
zip --version

# Add this block to your ~/.bashrc or ~/.zshrc
# So these are set automatically in every new terminal

export AWS_REGION=ap-south-1
export ACCOUNT_ID=$(aws sts get-caller-identity --query Account --output text 2>/dev/null)

# Handy alias to check your current AWS identity
alias whoami-aws='aws sts get-caller-identity'

# Alias for the region you use most
alias aws-region='echo $AWS_REGION'