lsd — friendly DynamoDB CLI wrappers for AWS CLI

.lsd.sh

# lsd — friendly DynamoDB CLI wrappers
# Usage: lsd [subcommand] [args]
#   lsd                      list all tables
#   lsd info <table>         describe a table (schema, keys, indexes)
#   lsd scan <table> [n]     scan up to n items (default 20)
#   lsd get <table> <k> <v>  get a single item by partition key
#   lsd keys <table>         show just the key schema
#   lsd count <table>        approximate item count
#   lsd help                 show this help

lsd() {
  local cmd="${1:-list}"

  case "$cmd" in
    list|"")
      echo ""
      aws dynamodb list-tables \
        --query 'TableNames[]' \
        --output text \
        | tr '\t' '\n' \
        | sort \
        | while read -r name; do
            local count
            count=$(aws dynamodb describe-table \
              --table-name "$name" \
              --query 'Table.ItemCount' \
              --output text 2>/dev/null)
            printf "  %-40s  %s items\n" "$name" "$count"
          done
      echo ""
      ;;

    info)
      local table="${2:?Usage: lsd info <table>}"
      echo ""
      aws dynamodb describe-table --table-name "$table" \
        --query '{
          Table: Table.TableName,
          Status: Table.TableStatus,
          Items: Table.ItemCount,
          SizeBytes: Table.TableSizeBytes,
          Keys: Table.KeySchema,
          Attributes: Table.AttributeDefinitions,
          GSIs: Table.GlobalSecondaryIndexes[].IndexName,
          LSIs: Table.LocalSecondaryIndexes[].IndexName
        }' \
        --output yaml
      echo ""
      ;;

    scan)
      local table="${2:?Usage: lsd scan <table> [limit]}"
      local limit="${3:-20}"
      echo ""
      echo "Scanning $table (limit: $limit)..."
      echo ""
      aws dynamodb scan \
        --table-name "$table" \
        --max-items "$limit" \
        --output json \
        | python3 -c "
import json, sys
data = json.load(sys.stdin)
items = data.get('Items', [])
print(f'{len(items)} items returned')
print()
for i, item in enumerate(items, 1):
    flat = {k: list(v.values())[0] for k, v in item.items()}
    print(f'[{i}]', json.dumps(flat, indent=2, default=str))
    print()
"
      ;;

    get)
      local table="${2:?Usage: lsd get <table> <key> <value>}"
      local key="${3:?Usage: lsd get <table> <key> <value>}"
      local value="${4:?Usage: lsd get <table> <key> <value>}"
      echo ""
      local key_type
      key_type=$(aws dynamodb describe-table --table-name "$table" \
        --query "Table.AttributeDefinitions[?AttributeName=='$key'].AttributeType" \
        --output text)
      local type_map="S"
      [[ "$key_type" == "N" ]] && type_map="N"
      [[ "$key_type" == "B" ]] && type_map="B"
      aws dynamodb get-item \
        --table-name "$table" \
        --key "{\"$key\": {\"$type_map\": \"$value\"}}" \
        --output json \
        | python3 -c "
import json, sys
data = json.load(sys.stdin)
item = data.get('Item')
if not item:
    print('No item found.')
else:
    flat = {k: list(v.values())[0] for k, v in item.items()}
    print(json.dumps(flat, indent=2, default=str))
"
      echo ""
      ;;

    keys)
      local table="${2:?Usage: lsd keys <table>}"
      echo ""
      aws dynamodb describe-table --table-name "$table" \
        --query '{Keys: Table.KeySchema, Attributes: Table.AttributeDefinitions}' \
        --output yaml
      echo ""
      ;;

    count)
      local table="${2:?Usage: lsd count <table>}"
      local count
      count=$(aws dynamodb describe-table --table-name "$table" \
        --query 'Table.ItemCount' --output text)
      echo ""
      echo "  $table: ~$count items (approximate)"
      echo ""
      ;;

    help|--help|-h)
      echo ""
      echo "  lsd                      list all tables"
      echo "  lsd info <table>         describe table schema and indexes"
      echo "  lsd scan <table> [n]     scan up to n items (default 20)"
      echo "  lsd get <table> <k> <v>  get item by partition key"
      echo "  lsd keys <table>         show key schema only"
      echo "  lsd count <table>        approximate item count"
      echo "  lsd help                 show this help"
      echo ""
      ;;

    *)
      echo "Unknown command: $cmd. Run 'lsd help' for usage."
      return 1
      ;;
  esac
}