Infra (Automation Routers)

Infra groups are automation routers — they receive machine-generated messages and fan them out to other groups (typically Alerts or Intake). No humans are direct members. They’re the plumbing that connects noisy systems to the right downstream pipes.

Pattern

prv-{owner}-infra-{system}[-{scope}][-{env}]-{purpose}@{domain}

Design Principles

• No human subscribers. Infra groups route to other groups, not to people.
• Allowlisted senders. Only known systems can post.
• Moderation. MODERATE_ALL_MESSAGES with allowlist — unknown senders get quarantined, not delivered.
• Locked. Usually automation-managed (Terraform/GAM).

Common Infra Routers

Email	Purpose
prv-plt-infra-gl-ci-router	GitLab CI event classification and fan-out
prv-plt-infra-tf-plan-notify	Terraform plan/apply notifications
prv-plt-infra-aws-eventbridge-router	AWS EventBridge event routing
prv-plt-infra-bridge-{tenant}	Cross-tenant bridge router

Settings

• Who can post: Anyone + MODERATE_ALL_MESSAGES + allowlisted senders
• Members: Other groups only (Alerts, Intake, Mail). Zero humans.
• External posting: ON (source systems are often external)
• External members: ON (for sender allowlisting)
• Archive: ON
• Security label: OFF
• Locked: ON (automation-managed)
• Subject prefix: Recommended (e.g., [GL-CI], [TF-PLAN])

Router Flavors

Flavor	What It Does	Downstream
Fan-out	One source → multiple destinations	Multiple Alerts or Intake groups
Classifier	One source → classify by content → route to specific pipe	Topic-specific Alerts groups
Bridge	Cross-tenant routing	Another tenant’s Infra or Alerts
Aggregator	Many sources → one destination	Single Alerts or Intake group

Wiring Examples

Fan-Out Router

Terraform Cloud → prv-plt-infra-tf-plan-notify
                    ├→ prv-plt-alerts-tf-prd     (failures)
                    └→ prv-plt-intake-tf-audit    (all runs)

Classifier Router

GitLab → prv-plt-infra-gl-ci-router
           ├→ prv-sec-alerts-gl-security    (security events)
           ├→ prv-eng-alerts-gl-deploy      (deploy failures)
           └→ prv-plt-intake-gl-audit       (audit trail)

Cross-Tenant Bridge

Tenant A system → prv-plt-infra-bridge-pai
                    └→ pai-plt-alerts-shared-platform

Lifecycle

Create

1. Identify source system(s) and downstream destinations.
2. Set email/name/description.
3. Labels: Mailing=ON, Security=OFF, Locked=ON.
4. Set MODERATE_ALL_MESSAGES + allowlist source senders.
5. Add downstream groups as members (Alerts, Intake, or other Infra).
6. Verify zero human members.
7. Add subject prefix for downstream filtering.

Operate

• Monitor: quarantined messages (new source not yet allowlisted).
• Quarterly: review downstream routing, add/remove destinations.
• Verify: no humans have been added as members.

Retire

• Confirm no active sources route to this group.
• Update downstream groups that referenced this router.
• Export archive. Delete after hold.

Anti-Patterns

• Humans as direct members of Infra groups (use downstream Alerts/Mail instead)
• Infra groups without allowlists (becomes a spam sink)
• Direct system-to-Alerts without an Infra router when volume is high or classification is needed
• Infra groups on any ACLs

Metrics

Metric	Target
Human members in Infra groups	0
Quarantined messages (allowlist gap)	Investigated within 1 biz day
Downstream routing accuracy	100%
Quarterly routing review	Completed