Can we achieve Zero down time when there is setup:upgrade is happening

[Naveen-LinuxAwsguy]

is there any way we can achieve Zero downtime when we are upgrading the DB ?

[macieklewkowicz]

It should be possible, however not with vanilla Magento.

When there's anything to update in the database, setup:upgrade and app:config:import are performed automatically on Magento Pod initialization (https://github.com/KiweeEu/magento2-on-kubernetes/blob/2.4.6-p4-3/deploy/bases/app/magento-web.yaml#L90-L105). This would be sufficient to allow zero-downtime deployments if not for how Magento handles schema and data updates.

Because by default Magento displays an error on all pages when any schema versions in the database don't match those in the code, the new version won't work before setup:upgrade, and the old version breaks as soon as setup:upgrade is performed.

This means that you can either:

• have a brief maintenance window when database updates are being performed (as recommended in https://experienceleague.adobe.com/en/docs/commerce-operations/configuration-guide/deployment/technical-details#recommended-pipeline-deployment-workflow), or
• modify Magento's schema version handling so that it allows mismatch between schema and data versions in the database and the code (there are 3rd-party modules that do this but I cannot recommend any particular one)

[Naveen-LinuxAwsguy]

issue resolved