Upgrading Minor Versions in Zero Downtime
This section explains the steps to upgrade API Gateway in zero downtime for minor versions like fix versions of 10.5 fix 1 to 10.5 fix 2.
Prerequisites
The old instance of API Gateway must be up and running.
Upgrade in Cluster Deployments
Zero downtime upgrade in minor versions in a cluster setup is a rolling upgrade. Old nodes are brought down and taken out of the cluster one by one while new nodes are brought up and added to the cluster one by one. There is no data migration as both the old and new instances point to the same API Data Store.
The following image shows the workflow for a minor upgrade.
The steps for the process of minor upgrade in a cluster are explained in the following.
1. Shutdown one of the old API Gateway Nodes
You must shutdown the old nodes after all the active client sessions in that node are closed. You can invoke the following REST API to shutdown the old instance.
POST /invoke/wm.server.admin/shutdown
{
"bounce": "no",
"option": "drain",
"timeout": 10
}
The timeout value is depending on the number of active client sessions.
Note:
For 10.7 and above versions of API Gateway you can use the API
/rest/apigateway/shutdown
to shutdown the API Gateway server.
If the shutdown fails with error, restart all the instances and update the load balancer to route the traffic only to the instances, to go back to the original state before migration. Contact Software AG support team for help with all the relevant logs for further analysis.
2. Apply Fix and Start
When the node in Step 1 is shutdown, apply the fix and start again.
Note:
For Docker case the fix can't be applied on the old container. Instead a new container from an image already built with the fix is started. Make sure the IS configurations which are not stored in API Data Store and custom IS packages are pre-configured in the new containers when starting.
Repeat the above procedure for all the new nodes.
