Ignore rke_config.etcd_snapshot_create to prevent plan drift

[Akini98]

Purpose

Resolves #220. On-demand etcd snapshots taken via the Rancher UI/API ("Snapshot Now") set rke_config.etcd_snapshot_create.generation on the provisioning cluster object. The k8s-cluster module does not manage that field, so every subsequent terraform plan shows spurious in-place drift trying to null it (e.g. etcd_snapshot_create { generation = 1 -> null }).

Goals

Stop the drift while keeping scheduled snapshots Terraform-managed.

Approach

Add rke_config[0].etcd_snapshot_create to the cluster resource's existing lifecycle { ignore_changes = [...] } (alongside chart_values / machine_selector_config). On-demand snapshots stay a UI/API action; the schedule remains managed via the etcd_s3 input.

Release note

Fix: k8s-cluster no longer shows plan drift after an on-demand etcd snapshot is taken from the Rancher UI.

Documentation

The behavior is noted in the backups guide (#219, examples/BACKUPS.md §A.6).

Automation tests

N/A. Observed and reproduced on a live cluster: after a UI "Snapshot Now", terraform plan repeatedly proposed nulling etcd_snapshot_create; with this change the plan is clean. terraform fmt -check passes on the changed file.

Security checks

• No secrets committed? yes — single-line ignore_changes addition, no values.

Compatibility

Non-breaking — additive to ignore_changes, no variable/output surface change.

Related PRs

• Add cluster backups guide (etcd + Velero) #219 (docs: backups guide) — documents this drift in §A.6.

Other template sections (Training, Certification, Marketing, Migrations, Samples): N/A.

Summary by CodeRabbit

• Bug Fixes
  • Reduced unexpected Terraform plan drift for Kubernetes clusters after using the manual Snapshot Now action.
  • Subsequent applies should now stay stable while scheduled snapshot settings remain managed as expected.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4479af40-a295-4ae6-bfee-370fed109e23

📥 Commits

Reviewing files that changed from the base of the PR and between bb7138b and 6bbe281.

📒 Files selected for processing (1)

• modules/tenancy/k8s-cluster/main.tf

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📝 Walkthrough

Walkthrough

This change updates the rancher2_cluster_v2.this resource in modules/tenancy/k8s-cluster/main.tf, adding rke_config[0].etcd_snapshot_create to the lifecycle.ignore_changes list, with inline comments explaining that on-demand "Snapshot Now" actions mutate this field and previously caused plan drift.

Changes

Terraform Drift Fix

Layer / File(s)	Summary
Ignore on-demand snapshot drift modules/tenancy/k8s-cluster/main.tf	Adds rke_config[0].etcd_snapshot_create to the lifecycle.ignore_changes list on the cluster resource, with comments explaining that UI/API "Snapshot Now" actions mutate etcd_snapshot_create.generation, causing recurring plan drift; scheduled snapshots remain Terraform-managed via etcd_s3.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Related Issues: #220

Suggested Labels: bug, terraform

Suggested Reviewers: (none identified)

Poem
A rabbit hopped through Terraform's plan,
Found drift where a snapshot began,
"Ignore it now," it softly said,
"Let schedules stay, let noise be dead."
One tidy line, and calm again. 🐇

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: ignoring etcd snapshot creation to stop Terraform drift.
Description check	✅ Passed	The description covers purpose, approach, testing, compatibility, and related work, so it is mostly complete despite using different headings.
Linked Issues check	✅ Passed	The change satisfies #220 by adding rke_config[0].etcd_snapshot_create to ignore_changes while leaving scheduled snapshots managed.
Out of Scope Changes check	✅ Passed	No unrelated changes are apparent; the diff is limited to the requested ignore_changes adjustment and explanatory comments.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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