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dynamically get the nodeport host (#4158)
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Greetings,

This is an update to the example doc of [`Using
Kubevirt`](https://ansible.readthedocs.io/projects/molecule/examples/kubevirt).
The purpose is to **dynamically** get the NodePort host to replace the
hardcoded hostname that is used for the VM SSH connection.

**The problem we solved**
By fetching the `hostname` dynamically, we avoid using a pre-defined
host for the VM SSH connection, that will reduce the the potential
failures by the connection problem with the host. In this update, the
hostname for the SSH connection is fetched dynamically, which is the K8S
node where the VM is running.

I get this tested in our environment with @jangel97

Thanks.

Co-authored-by: Hong Yao <hoyao@redhat.com>
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yahoon and Hong Yao authored Sep 9, 2024
1 parent 2714d30 commit 6f71543
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7 changes: 5 additions & 2 deletions docs/examples/kubevirt.md
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Expand Up @@ -40,6 +40,9 @@ rules:
- apiGroups: [""]
resources: ["services"]
verbs: ["get", "list", "watch", "create", "delete", "patch", "edit"]
- apiGroups: [""]
resources: ["pods"]
verbs: ["get", "list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
Expand Down Expand Up @@ -67,17 +70,17 @@ You will need to substitute the following placeholders:

- This example is using ephemeral VMs, which enhance the speed of VM creation and cleanup. However, it is important to note that any data in the system will not be retained if the VM is rebooted.
- You don't need to worry about setting up SSH keys. The `create.yml` Ansible playbook takes care of configuring a temporary SSH key.
- The hostname for SSH connection to the VM is fetched dynamically, which is the K8S node where the VM is running.

## Config playbook

```yaml title="molecule.yml"
{!tests/fixtures/integration/test_command/molecule/kubevirt/molecule.yml!}
```

Please, replace the following parameters:
Please, replace the following parameter:

- `<Kubernetes VM Namespace>`: This should be replaced with the namespace in Kubernetes where you intend to create the KubeVirt VMs.
- `<Kubernetes Node FQDN>`: Change this to the fully qualified domain name (FQDN) of the Kubernetes node that Ansible will attempt to SSH into via the Service NodePort.

```yaml title="requirements.yml"
{!tests/fixtures/integration/test_command/molecule/kubevirt/requirements.yml!}
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Expand Up @@ -14,7 +14,7 @@
loop_control:
loop_var: vm

- name: Delete VM Instance in KubeVirt
- name: Delete NodePort Service in KubeVirt
kubernetes.core.k8s:
state: absent
kind: Service
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Expand Up @@ -10,15 +10,13 @@ platforms:
namespace: <Kubernetes VM Namespace>
ssh_service:
type: NodePort
nodeport_host: <Kubernetes Node FQDN>
ansible_user: cloud-user
memory: 1Gi
- name: rhel8
image: registry.redhat.io/rhel8/rhel-guest-image
namespace: <Kubernetes VM Namespace>
ssh_service:
type: NodePort
nodeport_host: <Kubernetes Node FQDN>
ansible_user: cloud-user
memory: 1Gi
provisioner:
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Expand Up @@ -57,3 +57,16 @@
- [ sudo, yum, install, -y, qemu-guest-agent ] # Installs qemu-guest-agent
- [ sudo, systemctl, start, qemu-guest-agent ] # Starts qemu-guest-agent
name: cloudinitdisk

- name: Fetch VM pod info
kubernetes.core.k8s_info:
api_version: v1
kind: Pod
label_selectors:
- "vm.kubevirt.io/name={{ vm.name }}"
namespace: "{{ vm.namespace }}"
register: vm_pod_info

- name: Extract the nodename from the VM pod info
ansible.builtin.set_fact:
nodeport_host: "{{ vm_pod_info.resources | map(attribute='spec.nodeName') | list | first }}"
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Expand Up @@ -17,8 +17,8 @@
{{
molecule_systems | default({}) | combine({
vm.name: {
'ansible_user': 'cloud-user',
'ansible_host': vm.ssh_service.nodeport_host,
'ansible_user': vm.ansible_user,
'ansible_host': nodeport_host,
'ansible_ssh_port': ssh_service_address,
'ansible_ssh_private_key_file': temporary_ssh_key_path
}
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