Upgrading your node to Corda Open Source Edition 4.12

Corda releases strive to be backwards compatible, so upgrading a node is fairly straightforward and should not require changes to applications. It consists of the following steps:

1. Drain the node
2. Make a backup of your node directories and/or database
3. Download Corda Open Source Edition
4. Upgrade the node to Corda 4.11 or later
5. Replace the corda.jar file with the new version
6. Update the configuration
7. Update the CorDapps.
8. Create legacy folders
9. Start the node with the run-migration-scripts subcommand
10. Start the node in the normal way
11. Undrain the node

The protocol is designed to tolerate node outages, so during the upgrade process peers on the network will wait for your node to come back.

Step 1: Drain the node

Before a node or application on it can be upgraded, the node must be put in Draining mode. This brings the currently running Flows to a smooth halt such that existing work is finished and new work is queuing up rather than being processed.

Draining flows is a key task for node administrators to perform. It exists to simplify applications by ensuring apps don’t have to be able to migrate workflows from any arbitrary point to other arbitrary points, a task that would rapidly become infeasible as workflow and protocol complexity increases.

To drain the node, run the gracefulShutdown command. This will wait for the node to drain and then shut down the node when the drain is complete.

Step 2: Make a backup of your node directories and/or database

It’s always a good idea to make a backup of your data before upgrading any server. This will make it easy to roll back if there’s a problem. You can simply make a copy of the node’s data directory to enable this. If you use an external non-H2 database please consult your database user guide to learn how to make backups.

We provide some backup recommendations if you’d like more detail.

Step 3: Download Corda Open Source Edition

Download the required version of Corda Open Source Edition; for more information, see Release packs and checksums.

Step 4: Upgrade the node to Corda 4.11 or later

Ensure your node is running Corda 4.11 or later.

Step 5: Replace corda.jar with the new version

Download the latest version of Corda from Maven. Make sure it’s available on your path, and that you’ve read the Release notes, in particular to discover what version of Java this node requires.

Step 6: Update the configuration

This step is only required when updating from versions less than or equal to 4.5.

Remove any transactionIsolationLevel, initialiseSchema, or initialiseAppSchema entries from the database section of your configuration.

Step 7: Update the CorDapps

When upgrading from Corda 4.11 to Corda 4.12 there are specific changes that need to be made to the CorDapps contract version and minimum platform version (MPV), see Upgrade 4.11 CorDapps for more information.

Step 8: Create legacy folders

When upgrading to 4.12 and the network contains a mix of 4.12 and pre-4.12 nodes, you must create a legacy-contracts folder and, if required, a legacy-jars folder. See Corda Open Source Edition 4.11 to 4.12 upgrade guide for details.

Step 9: Start the node with run-migration-scripts subcommand

Start the node with the run-migration-scripts sub-command with --core-schemas and --app-schemas.

java -jar corda.jar run-migration-scripts --core-schemas --app-schemas

The node will perform any automatic data migrations required, which may take some time. If the migration process is interrupted it can be continued simply by starting the node again, without harm. The node will stop automatically when migration is complete.

Step 10: Start the node in the normal way

Start the node in the normal way.

Step 11: Undrain the node

Finally, undrain the node to re-enable processing of new inbound flows.

You may now do any checks that you wish to perform, read the logs, and so on. When you are ready, use this command at the shell:

run setFlowsDrainingModeEnabled enabled: false

Your upgrade is complete.