Editing Cluster Operations (section)

== Cluster Upgrade ==
Assuming there are no other adjustments due to features and/or bugfixes, the basic process for upgrading a cluster is to upgrade one node at a time:

# Expand tarball in the home directory of the <code>opensearch</code> user
# Copy the certificates, keys, and CAs from the <code>config</code> directory of the current version into the new one
# Copy the <code>opensearch.yml</code> file from the current version into the new one and make any adjustments
# Copy the <code>jvm.options.d/heapsize.options</code> file from the current version into the new one
# Move the <code>opensearch</code> link in the home directory from the current version into the new one
# Reload and restart the opensearch process using the '''Rolling Restart''' process described above
# Wait for the cluster to get to a "GREEN" state before moving to the next node

This assumes that the systemd unit file uses the softlink to access the opensearch executable as described in [[OpenSearch Cluster Installation]].