Helm: Choose image conditionally

conditional-image-repository.md

How to conditionally choose an image in Helm

If you want to choose an image based on a condition, you can do it with the following example:

values.yaml

image:
  repository: my-docker-repo/my-image
  tag: "latest"
  pullPolicy: Always

app:
  db: mongodb://foo:bar@0.0.0.0:1234/mydb

deployment.yaml

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  ...
spec:
  ...
  template:
    ...
    spec:
      imagePullSecrets:
        - name: {{ .Values.app.pullSecret }}
      containers:
        - name: {{ .Chart.Name }}
          {{ if hasPrefix "db2" .Values.app.db }}
          image: "{{ .Values.image.repository }}-custom:{{ .Values.image.tag }}"
          {{ else }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          {{ end }}
          imagePullPolicy: {{ .Values.image.pullPolicy }}

** Notice that I've used the golang function hasPrefix to verify if the image name starts with db2.

Running with default value (mongodb)

When execute with default value, it will generate the default image:

helm install --dry-run --debug my-helm-chart | grep "image: "

Result: image: "my-docker-repo/my-image:latest"

Running with custom value (db2)

When execute with custom value, it will generate the custom image:

helm install \
  --set "app.db=db2://foo:bar@0.0.0.0:1234,0.0.0.1:2345/mydb?foo=bar" \
  --dry-run --debug my-helm-chart | grep "image: "

Result: image: "my-docker-repo/my-image-custom:latest"