Getting Started With ScyllaDB Alternator¶

Get ScyllaDB with Alternator support from a docker:¶

1. Download the latest stable ScyllaDB image for Docker, by running docker pull scylladb/scylla:latest

2. To run this Docker image, follow the instructions in https://hub.docker.com/r/scylladb/scylla/, but add to every docker run command a -p 8000:8000 before the image name and --alternator-port=8000 --alternator-write-isolation=always at the end. The “alternator-port” option specifies on which port Scylla will listen for the (unencrypted) DynamoDB API, and the “alternator-write-isolation” chooses whether or not Alternator will use LWT for every write. For example, docker run --name scylla -d -p 8000:8000 scylladb/scylla:latest --alternator-port=8000 --alternator-write-isolation=always. The --alternator-https-port=... option can also be used to enable Alternator on an encrypted (HTTPS) port. Note that in this case, the files /etc/scylla/scylla.crt and /etc/scylla/scylla.key must be inserted into the image, containing the SSL certificate and key to use.

Running AWS Tic Tac Toe demo app to test the cluster:¶

1. Follow the instructions on the AWS github page

2. Enjoy your tic-tac-toe game :-)

Setting up the python environment¶

Run the following commands on your machine, this will install boto3 python library which also contains drivers for DynamoDB:

sudo pip install --upgrade boto3

Running some simple scripts:¶

The following is a 3 scripts test that creates a table named usertable writes the famous hello world record to it, and then, reads it back.

1. Put the following create table example script in a python file and run it (changing local host to the address of your docker node if you are using docker):

import boto3
dynamodb = boto3.resource('dynamodb',endpoint_url='http://localhost:8000',
                  region_name='None', aws_access_key_id='None', aws_secret_access_key='None')

dynamodb.create_table(
    AttributeDefinitions=[
    {
        'AttributeName': 'key',
        'AttributeType': 'S'
    },
    ],
    BillingMode='PAY_PER_REQUEST',
    TableName='usertable',
    KeySchema=[
    {
        'AttributeName': 'key',
        'KeyType': 'HASH'
    },
    ])

2. Put the following write example script in a python file and run it (changing local host to the address of your docker node if you are using docker):

import boto3
dynamodb = boto3.resource('dynamodb',endpoint_url='http://localhost:8000',
                  region_name='None', aws_access_key_id='None', aws_secret_access_key='None')

dynamodb.batch_write_item(RequestItems={
    'usertable': [
        {
             'PutRequest': {
                 'Item': {
                     'key': 'test', 'x' : {'hello': 'world'}
                 }
             },
        }
    ]
})

3. Put the following read example script in a python file and run it (changing local host to the address of your docker node if you are using docker):

import boto3
dynamodb = boto3.resource('dynamodb',endpoint_url='http://localhost:8000',
                  region_name='None', aws_access_key_id='None', aws_secret_access_key='None')

print(dynamodb.batch_get_item(RequestItems={
    'usertable' : { 'Keys': [{ 'key': 'test' }] }
}))

You should see the record you inserted in step 2 along with some http info printed to screen.