Problem

When upgrading JIRA, an automated re-index happens. For larger organizations that need to minimize downtime this can be a significant hassle, and a way to work around it is needed.

Resolution

1. Edit or create <jira-home>/jira-config.properties: Edit the jira-config.properties file in Jira server.
2. Add the line upgrade.reindex.allowed=false.
3. To save further time, you may also want to add the line jira.autoexport=false to disable the automatic export that is generated as part of the upgrade process.
4. Restart JIRA before your upgrade to ensure the properties are picked up. 

When using Jira on kubernetes these steps can be applied:

1. Create a file named `jira-configmap.yaml` with the following content:

apiVersion: v1
kind: ConfigMap
metadata:
  name: jira-configmap
data:
  jira-config.properties: |
    upgrade.reindex.allowed=false

2. Apply the ConfigMap to your Kubernetes cluster using the following command:

kubectl apply -f jira-config -map.yaml

3. Then, you need to mount this ConfigMap to your Jira pod. You can do this by modifying your Helm values. Create a file named `values.yaml` with the following content:

additionalVolumes:
  - name: jira-config-properties
    configMap:
      name: jira-configmap

additionalVolumeMounts:
  - name: jira-config-properties
    mountPath: /var/atlassian/application-data/jira/jira-config.properties
    subPath: jira-config.properties

4. Upgrade Jira using the Helm upgrade command, include the `-f` flag to specify your `values.yaml` file:

helm upgrade --set image.tag=<your Jira version> -f values.yaml <your release name> atlassian/jira-software

5. This will upgrade Jira and set `upgrade.reindex.allowed=false` in `jira-config.properties`.