Carvel, default images and optional preresolution

README.md

Render with latest or default:

ytt -f image-config.yaml | kbld -f - -f pod-template.yaml

Render with specific version:

ytt -f image-config.yaml -v nginxVersion=1.20 | kbld -f - -f pod-template.yaml
ytt -f image-config.yaml -v nginxVersion=1.21 | kbld -f - -f pod-template.yaml

Render but don't resolve images:

ytt -f image-config.yaml -v preresolved=true -v nginxVersion=1.21 | kbld -f - -f pod-template.yaml

image-config.yaml

#@ load("@ytt:data", "data")

#! there must be a better way to do this.

#@ def nginxImage():
#@   if data.values and hasattr(data.values, "nginxVersion"):
#@     return 'nginx:' + data.values.nginxVersion
#@   else:
#@     return 'nginx'
#@   end
#@ end

#@ def preresolved():
#@   if data.values and hasattr(data.values, "preresolved"):
#@     return data.values.preresolved == "true"
#@   else:
#@     return False
#@   end
#@ end

---
apiVersion: kbld.k14s.io/v1alpha1
kind: Config
overrides:
  - image: nginx
    newImage: #@ nginxImage()
    preresolved: #@ preresolved()

pod-template.yaml

#@ load("@ytt:data", "data")
---
apiVersion: v1
kind: Pod
metadata:
  labels:
    run: nginx
    templatedLabel: #@ data.values.label
  name: nginx
spec:
  containers:
  - image: nginx
    name: nginx