#!python
import argparse
import errno
import os
import boto
from boto.compat import json
from boto.compat import six
DESCRIPTION = """Dump the contents of one or more DynamoDB tables to the local filesystem.
Each table is dumped into two files:
- {table_name}.metadata stores the table's name, schema and provisioned
throughput.
- {table_name}.data stores the table's actual contents.
Both files are created in the current directory. To write them somewhere else,
use the --out-dir parameter (the target directory will be created if needed).
"""
def dump_table(table, out_dir):
metadata_file = os.path.join(out_dir, "%s.metadata" % table.name)
data_file = os.path.join(out_dir, "%s.data" % table.name)
with open(metadata_file, "w") as metadata_fd:
json.dump(
{
"name": table.name,
"schema": table.schema.dict,
"read_units": table.read_units,
"write_units": table.write_units,
},
metadata_fd
)
with open(data_file, "w") as data_fd:
for item in table.scan():
# JSON can't serialize sets -- convert those to lists.
data = {}
for k, v in six.iteritems(item):
if isinstance(v, (set, frozenset)):
data[k] = list(v)
else:
data[k] = v
data_fd.write(json.dumps(data))
data_fd.write("\n")
def dynamodb_dump(tables, out_dir):
try:
os.makedirs(out_dir)
except OSError as e:
# We don't care if the dir already exists.
if e.errno != errno.EEXIST:
raise
conn = boto.connect_dynamodb()
for t in tables:
dump_table(conn.get_table(t), out_dir)
if __name__ == "__main__":
parser = argparse.ArgumentParser(
prog="dynamodb_dump",
description=DESCRIPTION
)
parser.add_argument("--out-dir", default=".")
parser.add_argument("tables", metavar="TABLES", nargs="+")
namespace = parser.parse_args()
dynamodb_dump(namespace.tables, namespace.out_dir)