[RFE] Allow configuration for Image Pull policy for machine-provisioning job

[felipe-colussi]

Is your feature request related to a problem? Please describe.
When creating a downstream cluster the ...-machine-provisioning job always try to pull the image set on machine-provision-image. That generates a problem on air-gapped environments.

Describe the solution you'd like
Create a global setting that can be used to configure the ImagePullPolicy for the machine-provisioning job.
The setting will have Always as the default ImagePullPolicy witch will keep the same behavior as it have now.
As discussed on the jira issue this will have no UI component.

SURE-6383

[felipe-colussi]

Validation Template

Root Cause

It was impossible to set the image pull policy for machine-provision image.

What was fixed, or what change have occurred

It was added a setting that allows the configuration of the machine-provision image pull policy.

Areas or cases that should be tested

Creation of new clusters.

The setting should be set during the "Rancher" initialization setting the env CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY.

The allowed values are: Always, Never or IfNotPresent.

When creating a downstream cluster the value passed to "image pull policy" for the machine-provision pod (-n fleet-default) should be the one set on the env.

Extra details / tests:

If the env/setting is not set the default value should be Always.

If the env contains a wrong value it should default to Always and output a info message saying that it was defaulted to Always.

This is case sensitive

What areas could experience regressions

None.

Are the repro steps accurate/minimal?

I think so.

[Josh-Diamond]

Ticket #42294 - Test Results - ✅

Verified on Rancher v2.8-fc12e7d779577d10ded1a8e249f51727848b878e-head:

Scenario	Test Case	Result
1.	Set CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY to Always => deploy a downstream cluster => verify setting in local cluster job for machine-provision pod	✅
2.	Set CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY to IfNotPresent => deploy a downstream cluster => verify setting in local cluster job for machine-provision pod	✅
3.	Set CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY to Never => deploy a downstream cluster => verify setting in local cluster job for machine-provision pod	✅

---

Scenario 1 -

1. Fresh install of Rancher v2.8-head w/ CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY set to Always
2. Provision a downstream RKE2 cluster, and while cluster is provisioning navigate to Cluster Explorer (local) > Workloads > Jobs > machine-provisioning job > Edit YAML and confirm imagePullPolicy
3. Verified - imagePullPolicy is set to Always; as expected

---

Scenario 2 -

1. Fresh install of Rancher v2.8-head w/ CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY set to IfNotPresent
2. Provision a downstream RKE2 cluster, and while cluster is provisioning navigate to Cluster Explorer (local) > Workloads > Jobs > machine-provisioning job > Edit YAML and confirm imagePullPolicy
3. Verified - imagePullPolicy is set to IfNotPresent; as expected

---

Scenario 3 -

1. Fresh install of Rancher v2.8-head w/ CATTLE_MACHINE_PROVISION_IMAGE_PULL_POLICY set to Never
2. Provision a downstream RKE2 cluster, and while cluster is provisioning navigate to Cluster Explorer (local) > Workloads > Jobs > machine-provisioning job > Edit YAML and confirm imagePullPolicy
3. Verified - imagePullPolicy is set to Never; as expected