iKnC4V4p

1import os
2import boto3
3import datetime
4
5region = os.environ.get('AWS_DEFAULT_REGION', 'us-west-2')
6dynamodb = boto3.client('dynamodb', region_name=region)
7
8class DailyResize(object):
9
10    FIRST_DAY_RCU, FIRST_DAY_WCU = 300, 1000
11    SECOND_DAY_RCU, SECOND_DAY_WCU = 100, 1
12    THIRD_DAY_RCU, THIRD_DAY_WCU = 1, 1
13
14    def __init__ (self, table_prefix):
15        self.table_prefix = table_prefix
16
17    def create_new(self):
18        # create new table (300 RCU, 1000 WCU)
19        today = datetime.date.today()
20        new_table_name = "%s_%s" % (self.table_prefix, self._format_date(today))
21        dynamodb.create_table(
22            TableName=new_table_name,
23            KeySchema=[       
24                { 'AttributeName': "pk", 'KeyType': "HASH"}, # Partition key
25                { 'AttributeName': "sk", 'KeyType': "RANGE" } # Sort key
26            ],
27            AttributeDefinitions=[       
28                { 'AttributeName': "pk", 'AttributeType': "N" },
29                { 'AttributeName': "sk", 'AttributeType': "N" }
30            ],
31            ProvisionedThroughput={       
32                'ReadCapacityUnits': self.FIRST_DAY_RCU, 
33                'WriteCapacityUnits': self.FIRST_DAY_WCU,
34            },
35        )
36
37        print("Table created with name '%s'" % new_table_name)
38        return new_table_name
39
40
41    def resize_old(self):
42        # update yesterday's table (100 RCU, 1 WCU)
43        yesterday = datetime.date.today() - datetime.timedelta(1)
44        old_table_name = "%s_%s" % (self.table_prefix, self._format_date(yesterday))
45        self._update_table(old_table_name, self.SECOND_DAY_RCU, self.SECOND_DAY_WCU)
46
47        # update the day before yesterday's table (1 RCU, 1 WCU)
48        the_day_before_yesterday = datetime.date.today() - datetime.timedelta(2)
49        very_old_table_name = "%s_%s" % (self.table_prefix, self._format_date(the_day_before_yesterday))
50        self._update_table(very_old_table_name, self.THIRD_DAY_RCU, self.THIRD_DAY_WCU)
51
52        return "OK"
53
54
55    def _update_table(self, table_name, RCU, WCU):
56        """ Update RCU/WCU of the given table (if exists) """
57        print("Updating table with name '%s'" % table_name)
58        try:
59            dynamodb.update_table(
60                TableName=table_name,
61                ProvisionedThroughput={
62                    'ReadCapacityUnits': RCU,
63                    'WriteCapacityUnits': WCU,
64                },
65            )
66        except dynamodb.exceptions.ResourceNotFoundException as ex:
67            print("DynamoDB Table %s not found" % table_name)
68
69
70    @staticmethod
71    def _format_date(d):
72        return d.strftime("%Y-%m-%d")