Platform & DevOps·Infrastructure described in a file
you ran the package upgrade on the running fleet, and now the machines differ from each other by whatever failed halfway.
In-place upgrade
Also calledmutable update, patch in place
Modifying running machines rather than replacing them. It is faster and it preserves anything local, which is exactly why it accumulates divergence: every partial failure leaves a machine in a state no image describes. It remains the only option for genuinely long-lived stateful hosts, which is where the discipline of configuration management still earns its keep.