chore: apply conditional to version label partial tpl

Check whether the output of the 'application.version' partial template
is empty instead of the image tag when deciding whether to add the
Kubernetes recommended application version label.

The partial template was adjusted to avoid crashes when applying the
regexReplace function.

application/templates/_helpers.tpl

@@ -11,7 +11,8 @@ Define the name of the chart/application.
 Define the name of the chart/application.
 */}}
 {{- define "application.version" -}}
-{{ regexReplaceAll "[^a-zA-Z0-9_\\.\\-]" .Values.deployment.image.tag "-" | trunc 63 | trimSuffix "-" -}}
+  {{- $version := default "" .Values.deployment.image.tag -}}
+  {{- regexReplaceAll "[^a-zA-Z0-9_\\.\\-]" $version "-" | trunc 63 | trimSuffix "-" -}}
 {{- end -}}
 
 {{/*
@@ -39,8 +40,8 @@ Common labels
 */}}
 {{- define "application.labels" -}}
 helm.sh/chart: {{ include "application.chart" . }}
-{{- if .Values.deployment.image.tag }}
-app.kubernetes.io/version: {{ include "application.version" . | quote }}
+{{- with include "application.version" . }}
+app.kubernetes.io/version: {{ quote . }}
 {{- end }}
 app.kubernetes.io/managed-by: {{ .Release.Service }}
 app.kubernetes.io/part-of: {{ include "application.name" . }}

application/tests/deployment_test.yaml

@@ -50,6 +50,9 @@ tests:
       - equal:
           path: spec.template.spec.containers[0].image
           value: example-image:example-tag
+      - equal:
+          path: metadata.labels["app.kubernetes.io/version"]
+          value: example-tag
 
   - it: uses image digest when given
     set:
@@ -60,6 +63,8 @@ tests:
       - equal:
           path: spec.template.spec.containers[0].image
           value: example-image@sha256:example-digest
+      - isNull:
+          path: metadata.labels["app.kubernetes.io/version"]
 
   - it: uses both image digest and tag when given both
     set: