Difficulty: Beginner
Estimated Time: 12 minutes

Alternator is an open-source project that gives Scylla compatibility with Amazon DynamoDB.

This lab starts with an introduction to the project. Afterward, you’ll create a one-node Scylla cluster with Alternator enabled, and performing some basic operations on it, using Python.

The goal of Alternator is to deliver an open-source alternative to DynamoDB, deployable wherever a user would want: on-premises, on other public clouds like Microsoft Azure or Google Cloud Platform, or still on AWS (for users who wish to take advantage of other aspects of Amazon’s market-leading cloud ecosystem, such as the high-density i3en instances). DynamoDB users can keep their same client code unchanged. Alternator is written in C++ and is a part of Scylla.

You can read more about it in this blog post and in the documentation.

The three main benefits Scylla Alternator provides to DynamoDB users are:

  1. Cost: DynamoDB charges for read and write transactions (RCUs and WCUs). A free, open-source solution doesn’t.
  2. Performance: Scylla was implemented in modern C++. It supports advanced features that enable it to improve latency and throughput significantly.
  3. Openness: Scylla is open-source. It can run on any suitable server cluster regardless of location or deployment method.

This lab is part of Scylla University.

Congratulations! You have completed the Project Alternator: Getting Started Lab.

More Resources

Conclusion

In this lesson, you learned the basics of Alternator: the open-source DynamoDB Scylla API. You saw how to create a cluster, connect to it, write data, and read data. Future lessons will cover more advanced topics and more interesting examples, including data modeling, backup and restore, single region vs. multi-region, streams (CDC), encryption at rest, and more.

ScyllaDB: Project Alternator: Getting Started Lab

Step 1 of 2

Install and Setup a Cluster

In production, a Scylla cluster should have at least three nodes in a cluster. In this lab, just for the demonstration, you will start by creating a single node cluster with Alternator enabled.

Create a Scylla Cluster

If you haven’t done so yet, download the example from git:

git clone https://github.com/scylladb/scylla-code-samples.git

Go to the directory of the alternator example:

cd scylla-code-samples/alternator/getting-started

Start a one-node cluster with Alternator enabled.

By default, Scylla does not listen to DynamoDB API requests. To enable such requests, set the alternator-port configuration option to the port (8000 in this example), which will listen for DynamoDB API requests.

docker run --name some-scylla --hostname some-scylla -p 8000:8000 -d scylladb/scylla:4.4.0 --smp 1 --overprovisioned 1 --alternator-port=8000 --alternator-write-isolation=always

Wait a few seconds and make sure the cluster is up and running:

docker exec -it some-scylla nodetool status

In this example, you will use the Python language to interact with Scylla with the Boto 3 SDK for Python. It’s also possible to use the CLI or other languages such as Java, C#, Python, Perl, PHP, Ruby, Erlang, Javascript.

Next, if you don’t already have it set up, install boto3 python library, which also contains drivers for DynamoDB:

sudo pip install --upgrade boto3

In the three scripts create.py read.py and write.py change the value for “endpoint_url” to the IP address of the node. Copy the IP address from the output of the previously used "nodetool status" command, then edit the three files and replace the IP address:

scylla-code-samples/alternator/getting-started/create.py

scylla-code-samples/alternator/getting-started/read.py

scylla-code-samples/alternator/getting-started/write.py