Network

The network interface manager detects the host IP and primary interface used for agent identity and networking features. It runs an initial detection at start and refreshes periodically.

Code: internal/network/

Purpose

• Select IOFog/Edgelet network interface per config rules
• Track current IP address and hostname
• Provide gateway IP helpers for DNS resolver scopes
• Periodic refresh (60s while IP unset, 30 minutes when IP is known)

Dependencies

Depends on	Reason
config	Interface selection preferences

Used by	Reason
supervisor	Started before Field Agent
dnsresolver	GatewayIPForScope() for listener bind addresses
processmanager	Network setup for workloads
runtimeapi	Status/info enrichment

Lifecycle

Start

1. Sync tier. Up to 5 UpdateNetworkInterface() attempts with 200ms spacing (≤~3s blocking)
2. On IP found: start periodic refresh goroutine; return nil
3. On sync failure: log WARN, leave empty IP, return nil (degraded continue. Supervisor and Field Agent proceed)
4. Async recovery. When sync tier leaves IP empty, a background goroutine runs up to 10 more attempts (15 total) with exponential backoff (30s base, double each loop, 8 min cap)
5. Periodic refresh. 60s while IP empty; 30 min when IP is set; errors are logged and the same goroutine continues (no respawn)

Stop

Cancel context (stops periodic update and async recovery).

Key APIs

Function	Role
GetCurrentIPAddress()	Agent IP for status
GetNetworkInterfaceInfo()	Interface + address struct
GatewayIPForScope	Used by embedded DNS

Configuration

Interface selection driven by config fields (controller-facing IP discovery). See internal/config for NetworkInterface related settings in default profiles.

External APIs

No dedicated EdgeletAPI routes; IP/interface appear in system status/info payloads.

Observability

• Log module: "Network Interface Manager"
• Errors on failed interface update logged at start

Failure modes

Symptom	Typical cause
Empty IP at boot (unable to retrieve ip address)	No usable IPv4 during sync tier; agent continues in degraded mode and retries async + periodic
IP appears after boot delay	Far-edge link or DHCP late; async recovery or 60s periodic picks up address
Wrong agent IP on controller	Interface selection mismatch on multi-homed host
DNS bind failures	Gateway IP not available for scope

Code map

File	Role
manager.go	Detection, periodic update, gateway helpers

Related: DNS resolver, Status reporter.

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