Managing KubeVirt VMs with Ansible

2024-07-12 23:30| 来源: 网络整理| 查看: 265

Introduction

Infrastructure teams managing virtual machines (VMs) and the end users of these systems make use of a variety of tools as part of their day-to-day world. One such tool that is shared amongst these two groups is Ansible, an agentless automation tool for the enterprise. To simplify both the adoption and usage of KubeVirt as well as to integrate seamlessly into existing workflows, the KubeVirt community is excited to introduce the release of the first version of the KubeVirt collection for Ansible, called kubevirt.core, which includes a number of tools that you do not want to miss.

This article will review some of the features and their use associated with this initial release.

Note: There is also a video version of this blog, which can be found on the KubeVirt YouTube channel.

Motivation

Before diving into the featureset of the collection itself, let鈥檚 review why the collection was created in the first place.

While adopting KubeVirt and Kubernetes has the potential to disrupt the workflows of teams that typically manage VM infrastructure, including the end users themselves, many of the same paradigms remain:

Kubernetes and the resources associated with KubeVirt can be represented in a declarative fashion. In many cases, communicating with KubeVirt VMs makes use of the same protocols and schemes as non-Kubernetes-based environments. The management of VMs still represents a challenge.

For these reasons and more, it is only natural that a tool, like Ansible, is introduced within the KubeVirt community. Not only can it help manage KubeVirt and Kubernetes resources, like VirtualMachines, but also to enable the extensive Ansible ecosystem for managing guest configurations.

Included capabilities

As part of the initial release, an Ansible Inventory plugin and management module is included. They are available in the same distribution location containing Ansible automation content, Ansible Galaxy. The resources encompassing the collection itself are detailed in the following sections.

Inventory

To work with KubeVirt VMs in Ansible, they need to be available in Ansible鈥檚 hosts inventory. Since KubeVirt is already using the Kubernetes API to manage VMs, it would be nice to leverage this API to discover hosts with Ansible too. This is where the dynamic inventory of the kubevirt.core collection comes into play.

The dynamic inventory capability allows you to query the Kubernetes API for available VMs in a given namespace or namespaces, along with additional filtering options, such as labels. To allow Ansible to find the right connection parameters for a VM, the network name of a secondary interface can also be specified.

Under the hood, the dynamic inventory uses either your default kubectl credentials or credentials specified in the inventory parameters to establish the connection with a cluster.

Managing VMs

While working with existing VMs is already quite useful, it would be even better to control the entire lifecycle of KubeVirt VirtualMachines from Ansible. This is made possible by the kubevirt_vm module provided by the kubevirt.core collection.

The kubevirt_vm module is a thin wrapper around the kubernetes.core.k8s module and it allows you to control the essential fields of a KubeVirt VirtualMachine鈥檚 specification. In true Ansible fashion, this module tries to be as idempotent as possible and only makes changes to objects within Kubernetes if necessary. With its wait feature, it is possible to delay further tasks until a VM was successfully created or updated and the VM is in the ready state or was successfully deleted.

Getting started

Now that we鈥檝e provided an introduction to the featureset, it is time to illustrate how you can get up to speed using the collection including a few examples to showcase the capabilities provided by the collection.

Prerequisites

Please note that as a prerequisite, Ansible needs to be installed and configured along with a working Kubernetes cluster with KubeVirt and the KubeVirt Cluster Network Addons Operator. The cluster also needs to have a secondary network configured, which can be attached to VMs so that the machine can be reached from the Ansible control node.

Items covered Installing the collection from Ansible Galaxy Creating a Namespace and a Secret with an SSH public key Creating a VM Listing available VMs Executing a command on the VM Removing the previously created resources Walkthrough

First, install the kubevirt.core collection from Ansible Galaxy:

ansible-galaxy collection install kubevirt.core

This will also install the kubernetes.core collection as a dependency.

Second, create a new Namespace and a Secret containing a public key for SSH authentication:

ssh-keygen -f my-key kubectl create namespace kubevirt-ansible kubectl create secret generic my-pub-key --from-file=key1=my-key.pub -n kubevirt-ansible

With the collection now installed and the public key pair created, create a file called play-create.yml containing an Ansible playbook to deploy a new VM called testvm:

- hosts: localhost connection: local tasks: - name: Create VM kubevirt.core.kubevirt_vm: state: present name: testvm namespace: kubevirt-ansible labels: app: test instancetype: name: u1.medium preference: name: fedora spec: domain: devices: interfaces: - name: default masquerade: {} - name: secondary-network bridge: {} networks: - name: default pod: {} - name: secondary-network multus: networkName: secondary-network accessCredentials: - sshPublicKey: source: secret: secretName: my-pub-key propagationMethod: configDrive: {} volumes: - containerDisk: image: quay.io/containerdisks/fedora:latest name: containerdisk - cloudInitConfigDrive: userData: |- #cloud-config # The default username is: fedora name: cloudinit wait: yes

Run the playbook by executing the following command:

ansible-playbook play-create.yml

Once the playbook completes successfully, the defined VM will be running in the kubevirt-ansible namespace, which can be confirmed by querying for VirtualMachines in this namespace:

kubectl get VirtualMachine -n kubevirt-ansible

With the VM deployed, it is eligible for use in Ansible automation activities. Let鈥檚 illustrate how it can be queried and added to an Ansible inventory dynamically using the plugin provided by the kubevirt.core collection.

Create a file called inventory.kubevirt.yml containing the following content:

plugin: kubevirt.core.kubevirt connections: - namespaces: - kubevirt-ansible network_name: secondary-network label_selector: app=test

Use the ansible-inventory command to confirm the VM becomes added to the Ansible inventory:

ansible-inventory -i inventory.kubevirt.yml --list

Next, make use of the host by querying for all of the facts exposed by the VM using the setup module:

ansible -i inventory.kubevirt.yml -u fedora --key-file my-key all -m setup

Complete the lifecycle of the VM by destroying the previously created VirtualMachine and Namespace. Create a file called play-delete.yml containing the following playbook:

- hosts: localhost tasks: - name: Delete VM kubevirt.core.kubevirt_vm: name: testvm namespace: kubevirt-ansible state: absent wait: yes - name: Delete namespace kubernetes.core.k8s: name: kubevirt-ansible api_version: v1 kind: Namespace state: absent

Run the playbook to remove the VM:

ansible-playbook play-delete.yml

More information including the full list of parameters and options can be found within the collection documentation:

https://kubevirt.io/kubevirt.core

What next?

This has been a brief introduction to the concepts and usage of the newly released kubevirt.core collection. Nevertheless, we hope that it helped to showcase the integration now available between KubeVirt and Ansible, including how easy it is to manage KubeVirt assets. A next potential iteration could be to expose a VM via a Kubernetes Service using one of the methods described in this article instead of a secondary interface as was covered in this walkthrough. Not only does it leverage existing models outside the KubeVirt ecosystem, but it helps to enable a uniform method for exposing content.

Interested in learning more, providing feedback or contributing? Head over to the kubevirt.core GitHub repository to continue your journey and get involved.

https://github.com/kubevirt/kubevirt.core

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