State Manager

Overview

The State Manager is a Go library (commons/pkg/statemanager) that manages the dgxc.nvidia.com/nvsentinel-state node label lifecycle across NVSentinel modules. It provides a state machine implementation with transition validation and observability for coordinating Fault Quarantine, Node Drainer, and Fault Remediation operations.

Purpose

Coordinates node lifecycle state across three modules operating on the same node:

fault-quarantine: Detects faults, applies quarantined state
node-drainer: Evacuates workloads, applies draining → drain-succeeded or drain-failed
fault-remediation: Executes recovery, applies remediating → remediation-succeeded or remediation-failed

Provides:

Single source of truth for node remediation status
State transition validation with metrics for unexpected flows
Terminal state detection (drain-failed, remediation-failed, remediation-succeeded)
Cancellation support (label removal from any state without validation)

State Machine

                ┌──────────────────┐
                │   [NO LABEL]     │  Healthy node
                └────────┬─────────┘
                         │
                         │ Fault detected
                         ▼
                ┌──────────────────┐
                │   quarantined    ├──────────────────────┐
                └────────┬─────────┘                      │
                         │                                │
                         │ Start drain                    │ No pods to drain
                         ▼                                │
                ┌──────────────────┐                      │
   Healthy ◄────┤     draining     │                      │
   event        └────────┬─────────┘                      │
   (cancel)              │                                │
      │                  │ Drain completed                │
      │         ┌────────┴────────┐                       │
      │         │                 │                       │
      │         ▼                 ▼                       │
      │  ┌───────────────┐  ┌────────────────┐            │
      │  │drain-failed   │  │drain-succeeded │◄───────────┘
      │  └───────────────┘  └──────┬─────────┘
      │    [TERMINAL]              │
      │                            │ Start remediation
      │                            ▼
      │                     ┌──────────────┐  Note: fault-remediation
      │                     │ remediating  │  only consumes drain-succeeded.
      │                     └──────┬───────┘  drain-failed is a terminal state.
      │                            │
      │                   ┌────────┴────────┐
      │                   │                 │
      │                   ▼                 ▼
      │            ┌─────────────┐  ┌──────────────┐
      │            │ remediation-│  │ remediation- │ [TERMINAL]
      │            │ succeeded   │  │   failed     │
      │            └─────┬───────┘  └──────────────┘
      │                  │
      │                  │ Healthy event
      ▼                  ▼
┌──────────────────────────────┐
│        [NO LABEL]            │
└──────────────────────────────┘

State Label Values

State	Applied By	Description	Terminal
(no label)	Any	Healthy node, no active fault handling	No
`quarantined`	fault-quarantine	Fault detected, node cordoned/tainted	No
`draining`	node-drainer	Workload evacuation in progress	No
`drain-succeeded`	node-drainer	All workloads evacuated successfully	No
`drain-failed`	node-drainer	Workload evacuation failed	Yes
`remediating`	fault-remediation	Remediation action in progress	No
`remediation-succeeded`	fault-remediation	Remediation completed successfully	Yes*
`remediation-failed`	fault-remediation	Remediation action failed	Yes

*Terminal until healthy event triggers label removal

State Transitions

From State	To State	Trigger
(no label)	`quarantined`	Fault detected
`quarantined`	`draining`	Drain initiated
`quarantined`	`drain-succeeded`	No pods to drain
`draining`	`drain-succeeded`	All pods evacuated
`draining`	`drain-failed`	Evacuation timeout/failure
`drain-succeeded`	`remediating`	Remediation initiated
`remediating`	`remediation-succeeded`	Remediation completed
`remediating`	`remediation-failed`	Remediation error
(any state)	(no label)	Healthy event (cancellation)

Example Flows

Successful remediation:

none → quarantined → draining → drain-succeeded → remediating → remediation-succeeded → none

No pods to drain:

none → quarantined → drain-succeeded → remediating → remediation-succeeded → none

Failed drain:

none → quarantined → draining → drain-failed [TERMINAL]

Canceled drain (healthy event):

none → quarantined → draining → none

Failed remediation:

none → quarantined → draining → drain-succeeded → remediating → remediation-failed [TERMINAL]