OMERO / Python 3 Rollout Plan

After recent questions regarding Python 3, a few first beta testers, and over 200 PRs, we’d like to get your feedback on the Python 3 rollout plan for OMERO covering the next few months. We’re happy to help developers migrate their scripts & plugins ASAP but it’s critical to have system administrators onboard as well. Read the Bad News below for why.

Roadmap

The current plan is to have a public milestone (either beta or release candidate) available in one month (early December) for deployment testing. A major component of that release will be the deployment guide for everyone to test and nitpick. We are primarily testing with the default Python 3.6 on CentOS 7 and some conda deployments. Help covering more platforms would be welcome.

Since the final update will require changing base packages on your deployment systems, we’d very much encourage everyone to give this a try before the general release is ready early 2020.

The Good News

Luckily, the upcoming OMERO version (currently planned as 5.6.0) will not be significantly different from 5.5. Other than the change of the base Python installation, there should be no significant hurdles:

• No database upgrade is needed.
• There are no changes in Java or Ice version.
• API changes are minimal and only where forced by the differences between Python 2 and Python 3.
• Updates to all the standard web plugins (e.g. figure, iviewer, parade, gallery, mapr) as well as cli plugins (e.g. duplicate, render) will be provided.

The Bad News

However, (you knew there was a catch) with the Python 2.7 countdown nearly counted down and support for OMERO’s current Django version (1.8) long since dropped, Python 2 will no longer be supported. All plugins, extensions, and user-code will need to be migrated.

As a result, all future security patches will only be available for OMERO 5.6 and greater. For your own safety, it will be imperative that you be ready to upgrade your OMERO installation early in 2020.

Comments welcome on the https://forum.image.sc/t/omero-python-3-rollout-plan/31278 forum thread.