PACMAN: Automazione della configurazione di rete in GARR, tra sfide tecnologiche e cambiamento culturale#

Francesco Lombardo

• Why: One of the more complete config-automation case studies on the program: full production deployment at national scale (~160 devices), with the cultural-change narrative that usually determines whether these projects survive.
• What: GARR-T's Ansible-based packet-layer configuration manager for its 135-device (now ~160) Juniper MX/PTX IP/MPLS backbone — replacing device-by-device SSH CLI work, with the entire fleet now "pacmanized" and PACMAN integrated into daily operations.
• How: YAML intent models per device + Jinja2 templates rendered by an Ansible engine with per-vendor modules (Juniper/Arista/Cisco), GitLab CI/CD with merge-request review as the change workflow, AWX scheduled jobs running plan-mode drift detection across all devices, results pushed to Git with last-commit-author attribution, and a NetBox plugin giving compliance dashboards. The honest half of the talk: CLI-era NOC resistance to Git/Docker/YAML, large-scale refactoring of legacy configs into per-device intent models, and cross-team (DevOps/NOC/eng) misalignment.
• Where applicable: GARR-specific implementation, but the pattern (template + SoT + CI review + scheduled drift checks) transfers to any mid-size operator. Roadmap: customer-premises routers, a workflow orchestrator, auto-remediation of non-compliant devices.