Getting started with DynamoDB

#!/bin/bash

# DynamoDB Getting Started Tutorial Script
# This script demonstrates basic operations with Amazon DynamoDB:
# - Creating a table
# - Writing data to the table
# - Reading data from the table
# - Updating data in the table
# - Querying data in the table
# - Deleting the table (cleanup)

set -uo pipefail

# Set up logging with secure permissions
LOG_DIR="${XDG_STATE_HOME:-.}/dynamodb-tutorial-logs"
mkdir -p "$LOG_DIR"
LOG_FILE="$LOG_DIR/dynamodb-tutorial-$(date +%Y%m%d-%H%M%S).log"
chmod 700 "$LOG_DIR"
touch "$LOG_FILE"
chmod 600 "$LOG_FILE"
exec > >(tee -a "$LOG_FILE") 2>&1

echo "Starting DynamoDB Getting Started Tutorial at $(date)"
echo "Logging to $LOG_FILE"

# Validate AWS CLI is configured
if ! command -v aws &> /dev/null; then
    echo "ERROR: AWS CLI is not installed or not in PATH"
    exit 1
fi

# Check AWS credentials are available
if ! aws sts get-caller-identity &> /dev/null; then
    echo "ERROR: AWS credentials not configured or invalid"
    exit 1
fi

# Function to check for errors in command output
check_error() {
    local output=$1
    local cmd_name=$2
    
    if echo "$output" | grep -qi "error\|failed"; then
        echo "ERROR detected in $cmd_name command:" >&2
        echo "$output" >&2
        return 1
    fi
    return 0
}

# Function to wait for table to be in ACTIVE state
wait_for_table_active() {
    local table_name=$1
    local max_attempts=60
    local attempt=0
    local status=""
    
    echo "Waiting for table $table_name to become ACTIVE..."
    
    while [[ "$status" != "ACTIVE" && $attempt -lt $max_attempts ]]; do
        sleep 5
        status=$(aws dynamodb describe-table --table-name "$table_name" --query "Table.TableStatus" --output text 2>/dev/null || echo "UNKNOWN")
        echo "Current status: $status"
        ((attempt++))
    done
    
    if [[ "$status" != "ACTIVE" ]]; then
        echo "ERROR: Table $table_name did not become ACTIVE within timeout period" >&2
        return 1
    fi
    
    echo "Table $table_name is now ACTIVE"
    return 0
}

# Track created resources for cleanup
declare -a RESOURCES=()

# Cleanup function
cleanup() {
    local exit_code=$?
    
    if [[ $exit_code -ne 0 ]]; then
        echo "Script encountered an error (exit code: $exit_code)" >&2
    fi
    
    echo ""
    echo "==========================================="
    echo "CLEANUP"
    echo "==========================================="
    echo "Resources to clean up:"
    for resource in "${RESOURCES[@]+"${RESOURCES[@]}"}"; do
        echo "- $resource"
    done
    echo ""
    
    if [[ ${#RESOURCES[@]} -gt 0 ]]; then
        echo "Proceeding with cleanup of all created resources..."
        
        for resource in "${RESOURCES[@]+"${RESOURCES[@]}"}"; do
            if [[ "$resource" == Table:* ]]; then
                local table_name="${resource#Table:}"
                echo "Deleting table: $table_name"
                if aws dynamodb delete-table --table-name "$table_name" 2>/dev/null; then
                    echo "Waiting for table deletion to complete..."
                    aws dynamodb wait table-not-exists --table-name "$table_name" 2>/dev/null || true
                else
                    echo "Warning: Failed to delete table $table_name" >&2
                fi
            fi
        done
        
        echo "Cleanup completed."
    fi
    
    return $exit_code
}

trap cleanup EXIT

# Validate table name
validate_table_name() {
    local name=$1
    if [[ ! $name =~ ^[a-zA-Z0-9._-]+$ ]] || [[ ${#name} -gt 255 ]]; then
        echo "ERROR: Invalid table name: $name" >&2
        return 1
    fi
    return 0
}

# Step 1: Create a table in DynamoDB
echo "Step 1: Creating Music table in DynamoDB..."

TABLE_NAME="Music"
validate_table_name "$TABLE_NAME"

CREATE_TABLE_OUTPUT=$(aws dynamodb create-table \
    --table-name "$TABLE_NAME" \
    --attribute-definitions \
        AttributeName=Artist,AttributeType=S \
        AttributeName=SongTitle,AttributeType=S \
    --key-schema AttributeName=Artist,KeyType=HASH AttributeName=SongTitle,KeyType=RANGE \
    --billing-mode PAY_PER_REQUEST \
    --table-class STANDARD \
    --tags Key=project,Value=doc-smith Key=tutorial,Value=amazon-dynamodb-gs 2>&1) || {
    echo "ERROR: Failed to create table" >&2
    exit 1
}

check_error "$CREATE_TABLE_OUTPUT" "create-table"
echo "$CREATE_TABLE_OUTPUT"

# Add table to resources list
RESOURCES+=("Table:$TABLE_NAME")

# Wait for table to be active
wait_for_table_active "$TABLE_NAME"

# Enable point-in-time recovery (best practice)
echo "Enabling point-in-time recovery for the $TABLE_NAME table..."

PITR_OUTPUT=$(aws dynamodb update-continuous-backups \
    --table-name "$TABLE_NAME" \
    --point-in-time-recovery-specification PointInTimeRecoveryEnabled=true 2>&1) || {
    echo "ERROR: Failed to enable PITR" >&2
    exit 1
}

check_error "$PITR_OUTPUT" "update-continuous-backups"
echo "$PITR_OUTPUT"

# Step 2: Write data to the DynamoDB table
echo "Step 2: Writing data to the $TABLE_NAME table..."

# Use a temporary file for item data
ITEMS_TEMP=$(mktemp)
trap "rm -f '$ITEMS_TEMP'" EXIT

cat > "$ITEMS_TEMP" << 'EOF'
{"Artist": {"S": "No One You Know"}, "SongTitle": {"S": "Call Me Today"}, "AlbumTitle": {"S": "Somewhat Famous"}, "Awards": {"N": "1"}}
{"Artist": {"S": "No One You Know"}, "SongTitle": {"S": "Howdy"}, "AlbumTitle": {"S": "Somewhat Famous"}, "Awards": {"N": "2"}}
{"Artist": {"S": "Acme Band"}, "SongTitle": {"S": "Happy Day"}, "AlbumTitle": {"S": "Songs About Life"}, "Awards": {"N": "10"}}
{"Artist": {"S": "Acme Band"}, "SongTitle": {"S": "PartiQL Rocks"}, "AlbumTitle": {"S": "Another Album Title"}, "Awards": {"N": "8"}}
EOF

declare -i item_num=0
while IFS= read -r item_data; do
    ((item_num++))
    ITEM_OUTPUT=$(aws dynamodb put-item \
        --table-name "$TABLE_NAME" \
        --item "$item_data" 2>&1) || {
        echo "ERROR: Failed to put item $item_num" >&2
        exit 1
    }
    check_error "$ITEM_OUTPUT" "put-item (item $item_num)"
    echo "Item $item_num added successfully"
done < "$ITEMS_TEMP"

# Step 3: Read data from the DynamoDB table
echo "Step 3: Reading data from the $TABLE_NAME table..."

# Get a specific item
GET_ITEM_OUTPUT=$(aws dynamodb get-item --consistent-read \
    --table-name "$TABLE_NAME" \
    --key '{"Artist": {"S": "Acme Band"}, "SongTitle": {"S": "Happy Day"}}' 2>&1) || {
    echo "ERROR: Failed to get item" >&2
    exit 1
}

check_error "$GET_ITEM_OUTPUT" "get-item"
echo "Retrieved item:"
echo "$GET_ITEM_OUTPUT"

# Step 4: Update data in the DynamoDB table
echo "Step 4: Updating data in the $TABLE_NAME table..."

# Update an item
UPDATE_ITEM_OUTPUT=$(aws dynamodb update-item \
    --table-name "$TABLE_NAME" \
    --key '{"Artist": {"S": "Acme Band"}, "SongTitle": {"S": "Happy Day"}}' \
    --update-expression "SET AlbumTitle = :newval" \
    --expression-attribute-values '{":newval": {"S": "Updated Album Title"}}' \
    --return-values ALL_NEW 2>&1) || {
    echo "ERROR: Failed to update item" >&2
    exit 1
}

check_error "$UPDATE_ITEM_OUTPUT" "update-item"
echo "Updated item:"
echo "$UPDATE_ITEM_OUTPUT"

# Step 5: Query data in the DynamoDB table
echo "Step 5: Querying data in the $TABLE_NAME table..."

# Query items by Artist
QUERY_OUTPUT=$(aws dynamodb query \
    --table-name "$TABLE_NAME" \
    --key-condition-expression "Artist = :name" \
    --expression-attribute-values '{":name": {"S": "Acme Band"}}' 2>&1) || {
    echo "ERROR: Failed to query table" >&2
    exit 1
}

check_error "$QUERY_OUTPUT" "query"
echo "Query results:"
echo "$QUERY_OUTPUT"

echo "DynamoDB Getting Started Tutorial completed successfully at $(date)"
echo "Log file: $LOG_FILE"