In Kubernetes, is it possible to use a Configmap for the value of an annotation? The reason I want to do this is to reuse an IP whitelist across multiple ingresses. Alternatively, is there another way to approach this problem?
Unfortunately, no feature does it in Kubernetes. But as iomv wrote, you could try to use helm.
Helm allows you to use variables in your charts, for example:
metadata:
{{- if .Values.controller.service.annotations }}
annotations:
{{ toYaml .Values.controller.service.annotations | indent 4 }}
{{- end }}
labels:
{{- if .Values.controller.service.labels }}
{{ toYaml .Values.controller.service.labels | indent 4 }}
{{- end }}
app: {{ template "nginx-ingress.name" . }}
chart: {{ .Chart.Name }}-{{ .Chart.Version }}
component: "{{ .Values.controller.name }}"
heritage: {{ .Release.Service }}
release: {{ .Release.Name }}
name: {{ template "nginx-ingress.controller.fullname" . }}This part of code is from the nginx-ingress chart. As you see, you can fetch this chart and update the values as you need.