https://www.sirmysterion.com/tags/kustomize/Recent content in Kustomize on Thomas PetersHugoenthomas@tnepeters.com (Thomas Peters)thomas@tnepeters.com (Thomas Peters)<a href="https://creativecommons.org/licenses/by-nc/4.0/" target="_blank" rel="noopener">CC BY-NC 4.0</a>Mon, 10 Aug 2026 21:07:53 -0600https://www.sirmysterion.com/posts/20260810-multitenant-kubernetes-kustomize-appsets/Mon, 10 Aug 2026 00:00:00 +0000thomas@tnepeters.com (Thomas Peters)https://www.sirmysterion.com/posts/20260810-multitenant-kubernetes-kustomize-appsets/<h1 id="the-problem">The Problem</h1> <p>I&rsquo;ve been building a platform that runs the same application for multiple clients, with multiple users per client. Every instance needs its own config, its own storage, and its own hostname. Client A must never be able to reach client B, and that one has to be a guarantee rather than a convention. Users inside a client are a softer boundary, which is a distinction worth making early because the design treats them very differently. The naive approach is copy-pasting a pile of YAML per tenant, which works right up until you need to change one field across twenty instances.</p>