Automating Helm using Ansible

Increasing business demands are driving the need for increased automation to support rapid, yet stable, and reliable deployments of applications and supporting infrastructure. Kubernetes and cloud-native technologies are no different. For the Kubernetes platform, Helm is the standard means of packaging, configuring and deploying applications and services onto any cluster.

We recently released the kubernetes.core 1.1, our first Red Hat Certified Content Collection release, for general use. A big part of the new content that has been introduced is support for automating Helm operations. In this blog post, I will show you some common scenarios for its use in your automation.

Please note that prior to the release of kubernetes.core 1.1, its contents were released as community.kubernetes. With this content becoming Red Hat support and certified content, a name change was in order. We are in the process of making that transition.

A Quick Introduction to Helm

Helm is an open source tool used for packaging and deploying applications on Kubernetes. It is often called Kubernetes Package Manager. It is widely adopted by the Kubernetes community and the Cloud Native Computing Foundation (CNCF) graduate project.

Helm simplifies deployment of the applications by abstracting many of the complexities. This enables easier adoption and allows teams to be more productive.

Helm is designed as a Package Manager specifically for Kubernetes. It supports operations like install, remove, upgrade, rollback and downgrade for Kubernetes applications. As you may know, Kubernetes applications can be defined using declarative resource files for different Kubernetes objects like Deployment, Services, ConfigMaps, PersistentVolumeClaims and so on. Distributing and managing Kubernetes applications is difficult. Helm packages all Kubernetes resource files into a format called "Charts". Chart can be considered as the Kubernetes Package. This packaging format contains information about resource files, dependencies information and metadata.

Automating Helm using Ansible

You can automate your Kubernetes infrastructure using Ansible. All Kubernetes modules are now located in the Kubernetes Collection called kubernetes.core. This Collection also contains modules to automate Helm and its related functionalities.

The following is the list of Helm related modules included in the kubernetes.core Collection -

helm - Manages K8S packages with the Helm binary
helm_info - Gather information on Helm packages deployed inside the cluster
helm_plugin - Manage Helm plugins
helm_plugin_info - Gather information about Helm plugins
helm_repository - Manage Helm repositories

Helm modules take advantage of the Helm binary installed on Ansible controllers. This makes helm modules work out of the box and readily available for the users. Unlike the previous helm module, these are independent of any third party Python libraries. A special thanks to LucasBoisserie for his contributions.

Let us take a look at these modules used in some common scenarios.

Scenario 1 - Adding new Helm Repository

In order to install the Helm Package, you need to have the Helm repository added in your Kubernetes cluster.

Let us now add a Helm Repository using helm_repository module:

---
- hosts: localhost
  vars:
     helm_chart_url: "https://charts.bitnami.com/bitnami"
  tasks:
      - name: Add helm repo
        kubernetes.core.helm_repository:
            name: bitnami
            repo_url: "{{ helm_chart_url }}"

Here, we are installing a new Helm Chart Repository by specifying URL and name. After running this playbook, you will have Bitnami Chart Repository installed in your environment.

# helm repo list
NAME     URL
stable     https://kubernetes-charts.storage.googleapis.com/
bitnami    https://charts.bitnami.com/bitnami

Scenario 2 - Installing a Helm Chart

Now, we have the Helm repository configured. Let us now install nginx charts from the Bitnami repository.

---
- hosts: localhost
  tasks:
     - name: Install Nginx Chart
       kubernetes.core.helm:
           name: nginx-server
           namespace: testing
           chart_ref: bitnami/nginx

After running this playbook, you can see nginx-server deployment running in your testing environment.

# kubectl -n testing get deploy
NAME            READY   UP-TO-DATE   AVAILABLE   AGE
nginx-server      1/1     1            1           48s

Scenario 3 - Gather information about Helm Chart installed

Gathering information about the Helm Chart is also easy using the helm_info module.

---
- hosts: localhost
  tasks:
     - name: Gather information about nginx-server
       kubernetes.core.helm_info:
            name: nginx-server
            release_namespace: testing

Running this playbook will provide valuable information about the installed chart such as app version, chart version, revision, status and updated date time about the given chart.

Scenario 4 - Install Helm Plugin

Helm allows you to enhance its functionality by providing pluggable architecture. That means users can write plugins to enhance Helm functionality. There is a large number of Helm plugins available. Users can install those plugins depending on their use case and requirements.

Let us now try to install the Helm plugin called helm env. This helm plugin allows users to view the environment variables available to a helm plugin.

---
- hosts: localhost
  tasks:
     - name: Install Helm Plugin
       kubernetes.core.helm_plugin:
           plugin_path: https://github.com/adamreese/helm-env
           state: present
           release_namespace: testing

Scenario 5 - Gather information about Helm plugins

Users can gather information about installed Helm plugins from the given Kubernetes cluster.

---
- hosts: localhost
  tasks:
  - name: Gather Helm plugin info
    kubernetes.core.helm_plugin_info:
        release_namespace: testing
    register: r

  - name: Print plugin version
    debug:
    msg: "{{ ( r.plugin_list | selectattr('name', 'equalto', plugin_name) | list )[0].version }}"
    vars:
    plugin_name: "env"

This will output all the information related to plugins from the given namespace. Users can specify a particular plugin name to gather its information.

Conclusion & Next Steps

There you have it. With the Helm modules in kubernetes.core, you can easily automate the management of Kubernetes applications in a repeatable and reliable way. We hope you try it and let us know what you think. Please stop by at the Ansible Kubernetes IRC channel

ansible-kubernetes on Freenode to

provide your valuable feedback or if you need assistance with kubernetes.core Collection.

In a future post, we'll cover the rest of what's new in kubernetes.core and introduce the community.okd (OpenShift) Collection we are currently developing.