Vanilla

Definitions

Describing software in its unmodified, stock form, with no plugins, patches, extensions, or custom configuration. To run vanilla Kubernetes is to run the upstream release rather than a vendor distribution; a vanilla kernel is one built from Linus Torvalds' tree without a distributor's patch set. The word carries no criticism and is frequently a virtue, since vanilla configurations are the ones upstream actually tests, the ones documentation describes, and the ones maintainers will help debug. The standard troubleshooting instruction to reproduce a problem on a vanilla install exists precisely because local modification is the most common explanation for behaviour nobody else observes. The metaphor is the default ice cream flavour.
In plain English: Standard and uncustomized.
Example: "They kept the Kubernetes cluster as vanilla as possible so upgrades would not become another bespoke adventure."