# Version Upgrades

When deploying an upgrade to the Nekuti Matching Engine, operators should follow the below shutdown procedure to ensure state consistency across the upgrade. This process involves creating a snapshot immediately before shutting down, which guarantees that both the old and new versions of the engine agree on the system state.

Before upgrading the engine, call the SnapshotAndShutdown endpoint (Optionally, specify an exit code for the engine process):

curl -X 'PUT' \
  'http://control-gateway:8181/ExchangeWideControls/SnapshotAndShutdown?exitCode=12' \
  -H 'accept: application/json'

Wait for the endpoint to return its response before proceeding. The engine process will:

1. Create a complete snapshot of the current state
2. Return the HTTP response
3. Exit with the specified exit code (or zero if none provided)

Once the endpoint has returned and the engine process has exited, it is safe to:

1. Deploy the new version of the engine
2. Start the engine immediately

The engine will automatically load the snapshot created in Step 1 and resume operations.

It is safe to perform this upgrade procedure even when the engine version is not being upgraded.

1. Schedule upgrades during low-activity periods to minimize the impact of the longer restart time
2. Monitor the endpoint response to ensure the snapshot completes successfully
3. Test the upgrade procedure in a staging environment before production deployment