Upgrading to OpenJDK 21 on customer-hosted instances

Looker uses OpenJDK for performance and memory usage improvements. Starting in Looker 26.8, Looker supports OpenJDK version 21 on customer-hosted Looker instances. This page describes how to upgrade from OpenJDK 11 to OpenJDK 21. OpenJDK 11 will be deprecated on Looker, therefore we recommend all customer-hosted instances upgrade to OpenJDK 21.

Upgrading to OpenJDK 21 from OpenJDK 11 requires downloading and installing OpenJDK 21 and then downloading and installing a new looker startup script.

To upgrade to OpenJDK 21, follow these steps:

1. Stop the Looker process from shell, as the looker user:

   sudo su - looker
   cd /home/looker/looker
   ./looker stop
   

2. If you're updating a Looker cluster, repeat the previous step to stop Looker on every node.

3. Download and install OpenJDK 21.

4. Delete the previous version of the looker startup script from your looker directory:

   rm looker
   

5. Download the new looker21 startup script from the Looker public GitHub repository.

6. Replace the old startup script with the new looker21 script. To run properly, the new startup script must be named looker:

   mv <download_directory>/looker21 looker
   

7. If you're updating a Looker cluster, repeat steps 4 through 6 on all nodes.

8. Start up Looker on all nodes.

   ./looker start