Can Mattermost Community Edition migrate a small application with zero downtime using HA?

Goal

Migrate a small Mattermost application to a newer server version while keeping the API and web client available, using database schema migration and configuration changes already supported by the server.

Constraints

Mattermost applies supported schema migrations automatically during startup, but a single application node does not accept traffic while that migration runs. High Availability rolling restarts can reduce user-visible interruption, yet documented HA clustering is primarily an Enterprise feature, and Community Edition multi-node support depends on the specific release and license. Shared file storage is also required across nodes for attachments.

Questions

• Does Mattermost Community Edition support active-active HA nodes against one shared database for rolling restarts?
• Can a small Mattermost deployment complete a startup schema migration without any measurable API or web downtime?
• What configuration or licensing change is required before treating multi-node Mattermost as a zero-downtime migration path?