Even if your infrastructure is immutable, most things will still have mutable data... you can't just redeploy through any issue, because the issue could be with customer data.
Generally, that mutable data is on externally mounted volumes or stores though and not in the container itself, right? Except for what is read into container memory and written out to temporary or work files.
True, but restarting a service, remounting all the data, waiting until everything has synced etc, just to apply a security patch is a big downside of the immutable approach
Right, but my point is that a bad deploy can cause data corruption, which usually isn't fixed by just redeploying the previous version.