"Invalid Semantic Version" SemVer error when installing or upgrading Kong Gateway with Helm using an invalid `image.tag` value

When we attempt to install/upgrade Kong Gateway with an invalid SemVer image tag, we see a SemVer validation error similar to the following:

Error: template: kong/templates/deployment.yaml:273:3: executing "kong/templates/deployment.yaml" at <include "kong.proxy.compatibleReadiness" .>: error calling include: template: kong/templates/_helpers.tpl:1637:12: executing "kong.proxy.compatibleReadiness" at <semverCompare "< 3.3.0" (include "kong.effectiveVersion" .Values.image)>: error calling semverCompare: Invalid Semantic Version

This is not specific to Kong Gateway 3.4.0.0 — it occurs with any invalid-SemVer image.tag value on any current chart version. Note that on current chart versions (e.g. 3.4.1) the failure now typically surfaces much earlier in the template rendering, from the kong.metaLabels helper’s bare semver call (invoked by nearly every templated resource, including the proxy Service) rather than from kong.proxy.compatibleReadiness’s semverCompare call — so the exact template path, line numbers, and even which Sprig function (semver vs semverCompare) is named in the error you see may differ from the example above, though the root cause (an image.tag that fails Helm’s SemVer parsing, reported as Invalid Semantic Version) is the same.

Our helm chart performs several versioning checks against the provided image.tag in your values file. Those checks require the following version formats:

Enterprise Kong: X.X.X.X

Open Source Kong: X.X.X

If your image.tag field has anything outside of the above formatting, you will receive the above error.

Working example:

image:
  repository: kong/kong-gateway
  tag: 3.4.0.0

Broken example:

image:
  repository: kong/kong-gateway
  tag: randomletters