helm-app-operator

[DEPRECATED] Helm App Operator

This project is deprecated. Its functionality has been integrated into the Operator SDK as of v0.3.0. To get started developing a Helm operator with the SDK, see the Helm operator user guide.

Overview

The Helm App Operator is a component of the Operator Framework, an open source toolkit to manage Kubernetes native applications, called Operators, in an effective, automated, and scalable way. Read more in the introduction blog post.

The Helm App Operator makes it possible to leverage a pre-existing Helm chart to deploy Kubernetes resources as a unified application. It was inspired by the Lostromos project. The underlying operator was created using the operator-sdk.

Quick Start

This quick start guide walks through the process of building the Helm App Operator and extending it with an example Helm Chart.

Prerequisites

• dep version v0.5.0+.
• go version v1.10+
• docker version 17.03+
• Access to a kubernetes v1.9.0+ cluster

Install the Operator SDK CLI

First, checkout and install the operator-sdk CLI:

mkdir -p $GOPATH/src/github.com/operator-framework
cd $GOPATH/src/github.com/operator-framework
git clone https://github.com/operator-framework/operator-sdk.git
cd operator-sdk
make dep install

Initial Setup

Checkout this Helm App Operator repository:

cd $GOPATH/src/github.com/operator-framework
git clone https://github.com/operator-framework/helm-app-operator-kit.git
cd helm-app-operator-kit/helm-app-operator

Vendor the dependencies

make dep

Build the operator base image

Build the Helm App Operator base image and push it to a public registry, such as quay.io

export BASE_IMAGE=quay.io/example-inc/helm-app-operator:v0.0.1
operator-sdk build $BASE_IMAGE
docker push $BASE_IMAGE

Build a customized operator

Once you have a base image, the next step is to customize it to watch your custom resources and automate the deployment of your Helm Charts.

Configuration

The operator can be configured with a YAML file and environment variables.

YAML file

The watches.yaml file allows you to configure the operator to manage one or more custom resources and Helm charts. By default, the operator will look for this file at /opt/helm/watches.yaml. This value can be overridden by the HELM_CHART_WATCHES environment variable.

- group: apache.org
  version: v1alpha1
  kind: Tomcat
  chart: /charts/tomcat

Environment variables

Name	Description
HELM_CHART_WATCHES	The path to a configuration file that defines the operator watches (default: /opt/helm/watches.yaml).
API_VERSION	The <group/version> of the custom resource to watch.
KIND	The <Kind> of the custom resource to watch.
HELM_CHART	The path to a Helm chart directory
WATCH_NAMESPACE	The namespace in which the operator should watch for custom resource changes.

NOTE: API_VERSION, KIND, and HELM_CHART are supported to maintain backwards compatibility with older versions of this operator. New projects should use the configuration file to configure the watched CRDs and Helm charts.

Create a new project for your customized operator

We'll use a tomcat-operator as an example.

1. Create a project directory:

   mkdir -p tomcat-operator && cd tomcat-operator

2. Download the tomcat helm chart into tomcat-operator/helm-charts/:

   mkdir helm-charts
   wget -qO- https://storage.googleapis.com/kubernetes-charts/tomcat-0.1.0.tgz | tar vxz -C ./helm-charts

3. Create a watch configuration in tomcat-operator/watches.yaml:

   cat << EOF > watches.yaml
   ---
   - group: apache.org
     version: v1alpha1
     kind: Tomcat
     chart: /helm-charts/tomcat
   EOF

4. Create a Dockerfile:

   cat << EOF > Dockerfile
   FROM $BASE_IMAGE
   ADD watches.yaml /opt/helm/watches.yaml
   ADD helm-charts /helm-charts
   ENTRYPOINT ["/usr/local/bin/helm-app-operator"]
   EOF

5. Build the tomcat-operator Docker image

   export BASE_IMAGE=quay.io/example-inc/helm-app-operator:v0.0.1
   export TOMCAT_IMAGE=quay.io/example-inc/tomcat-operator:v0.0.1
   docker build -t $TOMCAT_IMAGE .
   docker push $TOMCAT_IMAGE

6. Create Kubernetes resource files for your CRD, CR, RBAC rules and operator

   The examples directory has examples of each of these files that can be used for the tomcat-operator (or modified for other uses).

   cp -r $GOPATH/src/github.com/operator-framework/helm-app-operator-kit/examples/tomcat-operator/ deploy/
   sed "s|REPLACE_IMAGE|$TOMCAT_IMAGE|" deploy/operator.yaml.template > deploy/operator.yaml && rm deploy/operator.yaml.template
   sed "s|REPLACE_IMAGE|$TOMCAT_IMAGE|" deploy/csv.yaml.template > deploy/csv.yaml && rm deploy/csv.yaml.template

7. Deploy the operator to your cluster

   export OPERATOR_NAMESPACE=default
   
   # As a simple deployment
   kubectl create -f deploy/crd.yaml
   kubectl create -n $OPERATOR_NAMESPACE -f deploy/rbac.yaml
   kubectl create -n $OPERATOR_NAMESPACE -f deploy/operator.yaml
   
   # OR
   
   # Using Operator Lifecycle Manager
   kubectl create -f deploy/crd.yaml
   kubectl create -n $OPERATOR_NAMESPACE -f deploy/csv.yaml

8. Create an instance of the Helm Chart

   kubectl create -n $OPERATOR_NAMESPACE -f deploy/cr.yaml