[codex] Document NOC BGP snapshot retention

[Svaag]

Summary

• add an operator runbook for the noc BGP router snapshot root filesystem incident
• document the temporary mitigation, permanent Ansible fix shape, and smoke checks for Prevent noc BGP router snapshots from filling root filesystem #321
• give low-root-filesystem NOC handoffs a stable source document to cite from Knowledge

Scope

• This is a prerequisite/source-context PR only.
• It does not close Prevent noc BGP router snapshots from filling root filesystem #321, [noc][lhp] case_0e77bc6b207d: resolve low root filesystem condition #300, or [noc][lhp] case_1552fd143bdf: resolve low root filesystem condition #299; the follow-up remediation PR still needs to implement managed retention and re-enable the snapshot timer safely.

Validation

• Not run; docs-only change.

Related

• Supports Prevent noc BGP router snapshots from filling root filesystem #321, [noc][lhp] case_0e77bc6b207d: resolve low root filesystem condition #300, and [noc][lhp] case_1552fd143bdf: resolve low root filesystem condition #299.

[github-actions]

PR Reviewer Guide 🔍

(Review updated until commit e0e643a)

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 321 - Partially compliant Compliant requirements: PR summary includes incident root cause and manual mitigation. Non-compliant requirements: Ansible ownership of timer/service not implemented. Retention enforcement not implemented. Retention horizon not yet configured in Ansible. Idempotency of playbook not verified by this change. Post-apply checks not performed by this PR. Requires further human verification: After apply checks (timer active, cleanup, free space, apt-get update) require deployment verification. 300 - Partially compliant Compliant requirements: (empty) Non-compliant requirements: None of the acceptance criteria are addressed by this documentation-only PR. Requires further human verification: All criteria require the operational fix and monitoring changes, not assessable via this docs PR. 299 - Partially compliant Compliant requirements: (empty) Non-compliant requirements: None of the acceptance criteria are addressed by this documentation-only PR. Requires further human verification: All criteria require the operational fix and monitoring changes, not assessable via this docs PR.

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🏅 Score: 85

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected

[github-actions]

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[github-actions]

Persistent review updated to latest commit e0e643a

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Run the NOC playbook from ansible/

This verification command is written for the repo root, but Ansible does not load ansible/ansible.cfg based on the playbook path; the documented config precedence is ANSIBLE_CONFIG, then ansible.cfg in the current directory. From the repo root that skips this repo's ansible/ansible.cfg (inventory = ./inventory/hosts.yml, roles_path = ./roles), so the playbook will not resolve the noc inventory and local roles reliably. Please cd ansible and use playbooks/noc.yml, or set ANSIBLE_CONFIG=ansible/ansible.cfg. See the Ansible config docs: https://docs.ansible.com/projects/ansible/latest/reference_appendices/config.html#the-configuration-file

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