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Namazu Archtecture

Overview

+----------+     +---------------+     +--------------------------------------------------+
|  Testee  | --- | EQ Inspector  | --- |                                                  |
+----------+     +---------------+     |                  EQ Orchestrator                 |
                                       |                                                  |
+----------+     +---------------+     |   * Receives events from the inspectors          |
|  Testee  | --- | EQ Inspector  | --- |   * Generate action set from events              |
+----------+     +---------------+     |     (Including injected fault actions)           |
                                       |   * Send actions to the inspectors               |
+----------+     +---------------+     |     in various orders                            |
|  Testee  | --- | EQ Inspector  | --- |                                                  |
+----------+     +---------------+     +--------------------------------------------------+
              ^                     ^
              |                     |
              |                     +--- Protocol Buffers, or REST (Inspectors POSTs events, then GETs actions)
              |
              +--- Inspectors (for Java) are embedded in testee programs using byteman

Inspectors

  • Java: byteman
  • Ethernet (ryu): Open vSwitch + ryu
  • Ethernet (nfqhook): iptables + NFQUEUE
  • Filesystem: FUSE
  • Process: Linux procfs and sched_setattr(2)

Orchestrator

Explore Policy: explores state space

  • Dumb: reorder nothing
  • Random: reorder actions randomly

History Storage

  • naive: single gob-encoded file
  • mongodb: MongoDB

REST API

  • POST /api/v3/events/<entity_id>/<event_uuid> (Non-blocking): send an event to the orchestrator
  • GET /api/v3/actions/<entity_id> (Blocking): receive an action for <entity_id> from the orchestrator.
  • DELETE /api/v3/actions/<entity_id>/<action_uuid> (Non-blocking): ack for get

Events:

  • JavaFunctionEvent: inspected and deferred function calls / returns
  • PacketEvent: inspected and deferred Ethernet packets
  • FilesystemEvent: inspected and deferred FUSE filesystem event
  • LogEvent: inspected syslog
  • ProcSetEvent: inspected procfs event

Actions:

  • NopAction: nop. just used for action history storage.
  • EventAcceptanceAction: accept an event
  • FilesystemFaultAction: fault for a FilesystemEvent
  • ProcSetSchedAction: set scheduling attribute (sched_setattr(2))

pynmz plug-ins (was available in v0.1, but removed since v0.2.0)

  • Orchestrator Plug-in: manages Explorer and so on.

  • BasicOrchestrator: a basic orchestrator

  • Explorer Plug-in: explores state space

  • DumbExplorer: reorder nothing

  • RandomExplorer: reorder actions randomly

  • TimeBoundedRandomExplorer: similar to RandomExplorer, but maximum deferred time is bounded

  • GreedyExplorer: DFS-like policy using NetworkX graph processing library

  • Process (now called "Entity") Watcher Plug-in: watches events from processes, maps event->action, and execute actions. You can check safety properties (i.e. assertion) in Process Watcher.

  • BasicProcessWatcher: a basic process watcher

  • Termination Detector Plug-in: detects termination of one-shot execution. Execution histories are recorded to storage on such terminations.

  • InspectionEndDetector: detects termination when InspectionEndEvents are observed from all processes

  • IdleForWhileDetector: detects termination when no event are observed for several milliseconds.