ryuheechul/patch-ipp-for-local.md

## patch-ipp-for-local.md

      
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              patch-ipp-for-local.md
            
          
    But why? At least three reasons:


You want to use local images without having to push to a remote registry


you probably just built an image locally and want to use that image with a helm chart
you can see the image when you run minikube image ls
but you still got an error on image pulling and the reason was imagePullPolicy: Always


with imagePullPolicy: Always, minikube (or probably limitation on k8s) will always attempt to pull from remote registry ignoring "locally pulled" ones


see more on that at https://minikube.sigs.k8s.io/docs/handbook/pushing/#3-pushing-directly-to-in-cluster-cri-o-podman-env
and https://kubernetes.io/docs/concepts/containers/images/#image-pull-policy
and https://kubernetes.io/docs/concepts/containers/images/#pre-pulled-images


Helm charts not always expose imagePullPolicy as editable values


so helm provide an escape hatch called "post rendering" that allows change the value of the templated YAML before pushing it to the k8s cluster
see more at https://helm.sh/docs/topics/advanced/#post-rendering
previously people tried the same with helm install --dry-run (or template) | [post_render] | kubectl apply -f -
but now it's much simpler just with --post-renderer


## patch-ipp-for-local.sh
#!/usr/bin/env bash

# This script is designed for `helm install --post-renderer ./patch-ipp-for-local.sh`

# It will patch `imagePullPolicy` to be `IfNotPresent` if it was `Always`
cat /dev/stdin | sed 's/imagePullPolicy: Always/imagePullPolicy: IfNotPresent/'

# Instead of `IfNotPresent`, `Never`can be used as well
# however, `Never` will make other remote images (like redis, postgres) not to be pulled
# unless those images already locally pulled which is probably not what you wanted

# Current limitation on this script: it won't work if `imagePullPolicy` doesn't exist in the first place:
# - in that case using `kustomize` will be much better than using simple `sed`
# - an example for above can be found at https://github.com/thomastaylor312/advanced-helm-demos/tree/master/post-render
	#!/usr/bin/env bash

	# This script is designed for `helm install --post-renderer ./patch-ipp-for-local.sh`

	# It will patch `imagePullPolicy` to be `IfNotPresent` if it was `Always`
	cat /dev/stdin \| sed 's/imagePullPolicy: Always/imagePullPolicy: IfNotPresent/'

	# Instead of `IfNotPresent`, `Never`can be used as well
	# however, `Never` will make other remote images (like redis, postgres) not to be pulled
	# unless those images already locally pulled which is probably not what you wanted

	# Current limitation on this script: it won't work if `imagePullPolicy` doesn't exist in the first place:
	# - in that case using `kustomize` will be much better than using simple `sed`
	# - an example for above can be found at https://github.com/thomastaylor312/advanced-helm-demos/tree/master/post-render