Upgrade FortiOS

Upgrading FortiOS on an Autoscale Group

The upgrade_fortios/ toolset upgrades a FortiGate autoscale group running in AWS. Two strategies are available, selected interactively at runtime based on the deployment’s current state and the operator’s risk tolerance.

Upgrade Strategies

Strategy	Best For	Traffic Impact	Rollback
In-Place	Same-major-version bumps on healthy deployments	Brief per-instance restart	Manual LT revert
Blue-Green	Cross-major-version upgrades, config remediation, or when full fallback is required	Near-zero (session interrupt at cutover)	Single script call, < 60 seconds

In-Place Upgrade Paths

The in-place strategy inspects live ASG state and selects the appropriate path automatically:

Path	Condition	What Happens
A	`desired = 0`, no running instances	Update launch templates only — no instance replacement
B	`desired > 0`, instances running	Rolling replacement: secondaries first, primary last
C	`desired = 0` + config backup present	Update LTs, launch primary, restore config, scale out

Blue-Green Upgrade Phases

The blue-green strategy deploys a parallel inspection stack and flips TGW routes at cutover:

Phase	Action	Duration
0 — Discovery	Extract Blue inventory from `terraform.tfstate`	30 min
1 — Backup	Export primary FortiGate configuration	30–60 min
2 — Deploy Green	`terraform apply` with new FortiOS AMI	30–60 min
3 — Validate Green	Health checks, config verification	30–60 min
4 — Cutover	Atomic TGW route flip + EIP migration	5–10 min
5 — Monitor	Blue suspended as fallback	24–48 hours
6 — Cleanup	`terraform destroy` Blue (irreversible)	1–2 hours

Overview

Strategy selection guide, toolset architecture, and prerequisites.

In-Place Upgrade

Paths A, B, and C — step-by-step procedures for in-place FortiOS upgrades.

Blue-Green Upgrade

Phase-by-phase guide for parallel deployment with TGW route flip cutover.

Discovery

How discover.py extracts the Blue environment from Terraform state and the blue_inventory.json schema used by all subsequent phases.

Toolset Location

All upgrade scripts, documentation, and state files live under:

upgrade_fortios/
├── scripts/
│   ├── discover.py          — Extract Blue inventory from terraform.tfstate
│   ├── inplace_upgrade.py   — In-place upgrade workflow (Paths A, B, C)
│   ├── cutover.py           — TGW route flip + NAT GW EIP migration
│   ├── rollback.py          — Revert TGW routes to Blue + EIP rollback
│   └── watch_lambda.sh      — Stream Lambda CloudWatch logs during upgrade
├── state/                   — Working directory for tfstate files and backups
└── README.md