helm-dump: a Helm plugin to create a Helm chart from existing cluster resources

Overview of the helm-dump plugin

Consider a case where as a Helm chart developer, you have configured a workload on either a Kubernetes or an OpenShift cluster. The requirement is to have this workload replicated either in the same or another OpenShift cluster by using a Helm chart. Use the helm-dump plug-in to create and export Helm charts based on the resources of a deployed workload available in an OpenShift or Kubernetes cluster. You can run the helm-dump plug-in against a namespace and generate a Helm chart for resources in the namespace that match a particular filter.

The helm-dump plug-in helps you transfer scalar values such as numbers or strings from a Helm chart template into the chart's values.yaml file.

Quick start

The quickstart showcases the helm-dump plug-in. You must install the plug-in and use it to create and export Helm charts. The quickstart consists of the following procedures:

1. Installing the helm-dump plug-in
2. Installing the template deployment
3. Labeling the Deployment resource
4. Extracting a Helm chart
5. Installing the newly created Helm chart into a cluster

Installing the helm-dump plug-in

Binary downloads of the helm-dump plug-in are available on the Releases page.

Prerequisites

You must have GoReleaser to manage the project's build process and compile this software.

Procedure

1. Download either the helm-dump_<VERSION>.tar.gz or helm-dump_<VERSION>.zip file.

2. Unpack its contents in the $HELM_PLUGINS directory:

# for HELM_PLUGINS environment variable
eval $(helm env)

# unpack the tarball
tar xvfz ~/Downloads/helm-dump_0.2.1.tar.gz -C "$HELM_PLUGINS"
# or the zip file
unzip -d "$HELM_PLUGINS" ~/Downloads/helm-dump_0.2.1.zip

3. After the bundle file is unpacked, you should view an output similar to the following:

$ helm dump 
A Helm plugin that creates a chart from a cluster's existing resources

Usage:
  helm-dump [command]

Available Commands:
  completion  generate the autocompletion script for the specified shell
  help        Help about any command
  version     print the helm-dump plugin version information

Flags:
      --config string   config file (default is $HOME/.helm_dump.yaml)
  -h, --help            help for helm-dump

Use "helm-dump [command] --help" for more information about a command.

The output verifies that the plugin is now available to use.

4. Build the helm-dump binary:

$ make build

Example output:

   • building...      
   • loading config file       file=.goreleaser.yaml
   • loading environment variables
   • getting and validating git state
      • building...               commit=eb2f496ae94abcf135f0df3d6d05c258c1df8bde latest tag=v0.2.1
      • pipe skipped              error=validation is disabled
...
   • building binaries
      • building                  binary=dist/helm-dump_windows_arm64/helm-dump.exe
      • building                  binary=dist/helm-dump_linux_arm64/helm-dump
      • building                  binary=dist/helm-dump_linux_s390x/helm-dump
      • building                  binary=dist/helm-dump_linux_arm_6/helm-dump
      • building                  binary=dist/helm-dump_linux_386/helm-dump
      • building                  binary=dist/helm-dump_darwin_amd64/helm-dump
      • building                  binary=dist/helm-dump_darwin_arm64/helm-dump
      • building                  binary=dist/helm-dump_linux_ppc64le/helm-dump
      • building                  binary=dist/helm-dump_linux_amd64/helm-dump
      • building                  binary=dist/helm-dump_windows_amd64/helm-dump.exe
   • storing release metadata
      • writing                   file=dist/artifacts.json
      • writing                   file=dist/metadata.json
   • build succeeded after 1.09s

5. Bundle thehelm-dump plug-in:

$ make plugin

Example output:

Building plugin in /home/isuttonl/Documents/src/helm-dump/dist/plugin/dump... Done!
Creating helm-dump_0.2.1.tar.gz... Done!
Creating helm-dump_0.2.1.zip... Done!
Calculating checksum for plugin bundles... Done!

The plug-in bundle has been built and stored at the ./dist/plugin/dump location and now you can install it in the system.

6. Install the plug-in bundle:

$ make install

Example output:

Installed plugin: dump

7. Verify that the plug-in installation is successful:

$ helm plugin list

Example output:

NAME    VERSION DESCRIPTION                                                           
dump    0.2.1   A Helm plugin that creates a chart from a cluster's existing resources

Installing the template deployment

This procedure uses the following example resource for the workload configuration in the form of a nginx-deployment.yaml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: default
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14.2
          ports:
            - containerPort: 80

Use this workload configuration to install a template deployment. This workload serves as a deployment that can get replicated in other environments based on the requirements.

Procedure

1. Install a simple deployment resource to apply the workload configuration into an available cluster:

For Kubernetes cluster:

kubectl apply -f nginx-deployment.yaml

For OpenShift cluster:

oc apply -f nginx-deployment.yaml

Example output:

deployment.apps/nginx-deployment created

2. Verify that the installation is successful:

For Kubernetes cluster:

kubectl get pods -n default

For OpenShift cluster:

oc get pods -n default

Example output:

NAME                    READY   STATUS    RESTARTS   AGE
nginx-deployment-9456bbbf9-8wgjb   1/1     Running   0          9s
nginx-deployment-9456bbbf9-bnmnk   1/1     Running   0          9s
nginx-deployment-9456bbbf9-fmszw   1/1     Running   0          9s

The output verifies that all pods are running.

Labeling the Deployment resource

You must label the Deployment resource so it can be included in the Helm chart that you are going to create and extract using the helm-dump plug-in.

Prerequisites

• You must have validated that the workload is properly running by exposing the deployment and the service.
• You must have validated that the workload is indeed working by using the curl command. This validation ensures that the nginx-deployment web server is successfully installed and working, and you have accessed the web server.

Note:

• If you have exposed the deployment and service successfuly, you must see a route for the nginx-deployment service similar to the following example:

Example:

route.route.openshift.io/nginx exposed

• You can label multiple resources, but this quickstart only focuses on the Deployment resource.

• Create a chart using helm dump and the labeled Deployment resource

After the workload is confirmed to work, the resource can be labeled to be collected by helm-dump at a later stage.

Procedure

• Label the Deployment resource:

kubectl label deployment nginx-deployment helm-dump=please

Example output:

deployment.apps/nginx-deployment labeled

The output verifies that you have labeled the resource successfully.

Extracting a Helm chart

Now that the Deployment resource is installed in the cluster and properly labeled, you can now extract this resource bundled in a Helm chart.

Procedure

1. Use the helm dump init command to extract the Deployment resource to a Helm chart:

helm dump init -l helm-dump=please my-chart /tmp/helm-dump-init-demo

Note:

• When you use -l helm-dump=please, the -l option has the same semantics as the kubectl option, so refer to kubectl --help for more information regarding its usage and semantics.

After extraction, the my-chart-0.1.0.tgz file is available at the /tmp/helm-dump-init-demo/ directory with the following chart and resource templates as its contents:

• Chart.yaml:

apiVersion: v2
name: my-chart # (1)
version: 0.1.0

1. Specifies the chart name as informed by the user when generating a chart using the helm-dump plug-in.

• templates/nginx-deployment_apps_v1.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"nginx-deployment","namespace":"default"},"spec":{"replicas":3,"selector":{"matchLabels":{"app":"nginx"}},"template":{"metadata":{"labels":{"app":"nginx"}},"spec":{"containers":[{"image":"nginx:1.14.2","name":"nginx","ports":[{"containerPort":80}]}]}}}}
  labels: # (1)
    app: nginx 
    app.kubernetes.io/instance: '{{ $.Release.Name }}'
    app.kubernetes.io/name: '{{ template "my-chart.fullname" $ }}'
    helm-dump: "please"
  name: nginx-deployment-{{ .Release.Name }} # (2)
  namespace: default
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx:1.14.2
        imagePullPolicy: IfNotPresent
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30

1. Specifies the labels added by the helm-dump plug-in according to the Helm guidelines.
2. Specifies the name field that is modified according to the Helm guidelines to include the release name at the time of deployment.

Installing the newly created Helm chart into a cluster

After you create and extract the Helm chart, now proceed to install the modified Helm chart into the cluster.

Procedure

1. Use the Helm chart to install a new release:

helm install my-app my-chart-0.1.0.tgz

Example output:

NAME: my-app
LAST DEPLOYED: Mon Apr 11 12:33:33 2022
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

2. Verify that the release is successfully installed in the cluster:

helm list

Example output:

NAME    NAMESPACE   REVISION    UPDATED                                     STATUS      CHART           APP VERSION
my-app  default     1           2022-04-11 12:33:33.854705256 +0200 CEST    deployed    my-chart-0.1.0

3. Verify the resources declared in the cluster:

kubectl get all

Example output:

NAME                                          READY   STATUS    RESTARTS   AGE
pod/nginx-deployment-9456bbbf9-4jgfc          1/1     Running   0          2m29s (1)
pod/nginx-deployment-9456bbbf9-mfpdc          1/1     Running   0          2m29s (1)
pod/nginx-deployment-9456bbbf9-w5h4f          1/1     Running   0          2m29s (1)
pod/nginx-deployment-my-app-9456bbbf9-4gkzx   1/1     Running   0          24s
 
pod/nginx-deployment-my-app-9456bbbf9-h2c2n   1/1     Running   0          24s
 
pod/nginx-deployment-my-app-9456bbbf9-rnmq2   1/1     Running   0          24s
 
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   6d1h
 
NAME                                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx-deployment          3/3     3            3           2m29s (2)
deployment.apps/nginx-deployment-my-app   3/3     3            3           24s   (3)
 
NAME                                                DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-deployment-9456bbbf9          3         3         3       2m29s
replicaset.apps/nginx-deployment-my-app-9456bbbf9   3         3         3       24s

1. Replicas from the resource that created the chart.
2. The resource that created the chart.
3. Resource created with the recently created Helm chart.

The output verifies that there is nginx-deployment deployment resource with three replicas that served as template, and nginx-deployment-my-app deployment resource with three replicas installed using the newly generated Helm chart.

The nginx-deployment deployment resource is extracted by the helm dump init command and the nginx-deployment-my-app deployment is managed by Helm.

License

Apache License Version 2.0