Redis

TL;DR Jellyfin dies mid-stream when a Kubernetes pod restarts because all transcode state is in-memory. I forked it, added a Redis-backed ITranscodeSessionStore, and wired in atomic lease-based pod takeover. The fork is at github.com/ZoltyMat/jellyfin-ha, and I also published a repo-level diff document at docs/FORK-DIFF.md showing exactly what changed versus upstream Jellyfin. Single-instance deployments need zero config changes because it falls back to a no-op store transparently. The Problem Jellyfin is great. It’s also built with the assumption that exactly one server instance is running at a time. Transcode state — which pods are running FFmpeg, what segments have been written, who owns a given play session — lives entirely in memory. When the process dies, that state is gone. ...

TL;DR Phase 3 is where the rubber meets the road. We have PostgreSQL for persistent data (Day 4) and NFS for shared config. But Jellyfin still holds critical runtime state — sessions, users, devices, tasks — in 11 ConcurrentDictionary instances scattered across singleton managers. Two pods with independent memory spaces means two independent views of reality. This post covers the state externalization decision: what got moved to Redis, what got solved by sticky sessions, what got disabled entirely, and why pragmatism beat perfection for a homelab media server. ...