Start to document known configuration parameters for common image rep…

…ositories (#208)

README.md

@@ -102,6 +102,12 @@ enrich version checking on image tags:
     is. In this example, the current version of `my-container` will be compared
     against the image versions in the `docker.io/bitnami/etcd` registry.
 
+## Known configurations
+
+From time to time, version-checker may need some of the above options applied to determine the latest version,
+depending on how the maintainers publish their images. We are making a conscious effort to collate some of these configurations.
+
+See [known-configurations.md](known-configurations.md) for more details.
 
 ## Metrics
 

known-configurations.md

@@ -0,0 +1,27 @@
+# Image Glossary
+
+This document serves as a reference for annotations required to be applied to various resources for the correct versions to be reported:
+
+## Images / Annotations
+
+### GKE Managed Images (kube-proxy, etc..)
+
+| Annotation | Reason |
+|-|
+| `use-metadata.version-checker.io/kube-proxy="true"` | This is because many GKE images are suffixed as `v.1.26.5-gke.2700` for example. By Default, version-checker removes tags with metadata (`-XXXX`) as these traditionally relate to an Alpha or pre-release image. |
+
+### Grafana: docker.io/grafana/grafana
+
+Grafana has a few images, when version-checker looks up the version, it inadvertently records these tags as latest, enforcing a strict Semantic Version (without a prefix) prevents this.
+
+|Annotation |
+|-|
+|`match-regex.version-checker.io/grafana='(\d+)\.(\d+)\.(\d+)'` |
+
+### Cert-Manager
+
+This is required as there's an image `608111629` which is detected as the latest, as Semver, this would equate to `608111629.0.0`.
+
+| Annotation |
+|-|
+| `match-regex.version-checker.io/cert-manager='v(\d+)\.(\d+)\.(\d+)` |