helm-import

Overview

A Helm plugin to import existing Kubernetes resources so they can be managed by a Helm chart. The use case is to allow Helm to manage resources that already exist without the need to delete and recreate them. Currently the plugin updates the following on every found after running the template command on the chart.

• Annotations
  • meta.helm.sh/release-name=RELEASE_NAME
  • meta.helm.sh/release-namespace=NAMESPACE
• Labels
  • app.kubernetes.io/managed-by=Helm

Note: We are using the helm template command and piping the output to kubectl. This means we cannot check if the resource already exists before adding the annotations and labels and must ignore errors. You must look at the output of the command to see if all resources were annotated and labelled properly. This allows the plugin to handle the use case where the chart will create a new resource as well as take over management of existing resources.

Install

helm plugin install https://github.com/jzbruno/helm-import/

Usage

helm import RELEASE_NAME CHART [args ...]

Test

This repo has an example chart that can be used for testing.

1. Create a Kubernetes deployment and service

   kubectl create ns test
   kubectl -n test apply -f ./charts/test/templates/deployment.yaml

2. Try to install the Helm chart

   helm upgrade --install test ./charts/test -n test

   You should see an error like

   Release "test" does not exist. Installing it now.
   Error: rendered manifests contain a resource that already exists. Unable to continue with install: Service "test" in namespace "test" exists and cannot be imported into the current release: invalid ownership metadata; annotation validation error: missing key "meta.helm.sh/release-name": must be set to "test"; annotation validation error: missing key "meta.helm.sh/release-namespace": must be set to "test"

3. Run the import plugin

   helm import test ./charts/test -n test

4. Run the install again

   helm upgrade --install test ./charts/test -n test

   Now you should see success

   Release "test" does not exist. Installing it now.
   NAME: test
   LAST DEPLOYED: Wed Nov 16 08:43:04 2022
   NAMESPACE: test
   STATUS: deployed
   REVISION: 1
   TEST SUITE: None

5. Cleanup

   helm uninstall -n test test