Key-Value Store

A distributed key value store implementation which uses Paxos made simple by Leslie Lamport to reach consensus. Here I am using dockers to setup a 3 node Paxos cluster which sits behind a proxy node. Proxy node also acts as a Load balancer which takes incoming requests and forwards it to Paxos cluster in Round robin fashion. The Key-Value store offers two basic operations get key-value pair and set key-value pair.

PAXOS

There are three basic roles:

• Proposers that propose a value for consensus.
• Acceptors that choose the consensus value.
• Learners that learn the consensus value.

A single process may take on multiple roles.

Failure Assumptions

• Processes can only fail by Crashing.
• Value Errors, Message omission errors are ignored.

Steps:

After cloning the repository, perform the below steps to start the Paxos cluster and Proxy server instance.

• docker-compose up
• To set a key value pair curl -X POST "http://localhost:8081/" -d "{\"key1\":\"val1\"}"
• To get a key value pair curl -X GET "http://localhost:8081/key=key1"

Tests

After cloning the repository, perform the below steps to run a test set with three test cases.

• pip3 install pytest
• cd tests
• pytest This will start the execution and all three test cases should pass.

References

Paxos Made Simple by Leslie Lamport (https://lamport.azurewebsites.net/pubs/paxos-simple.pdf)