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Hatohol server technical information

Kazuhiro Yamato edited this page Jul 10, 2014 · 18 revisions

Software stack of components related to data transfer directly

Classes

FaceRest

A REST interface to get unified data and configure Hatohol itself.

SessionManager

  • Authentication and Generation of session IDs.
  • Session IDs are on memory. So when hatohol server is restarted, all the session IDs are lost.
    • MEMO: We may use Memcached or a similar program to keep the session ID and share them by multiple programs in the future.
  • An expiration time of the session ID is 10 min from the last access with the ID.

ArmZabbixAPI, ArmNagiosNDOUtils

A component to get monitoring data from monitoring servers such as Zabbix server.

DBAgent

  • A base class to access DBs
  • Actual Subclassess: DBAgentMySQL and DBAgentSQLite3

DBClient

  • The subclasses do the following things
    • Provides C++ like API to access data in DB.
    • manages one or more tables on DB.
    • Convert data format: list or vector <==> ItemTable.

CacheServiceDBClient

  • A kind of connection pool for DB servers.
  • A thread uses a same connection while it's alive.

ItemTable and ItemGroup

ItemData

  • A virtual base class to handle various type of value with the same interfaces.
  • Implemented subclasses:
    • ItemInt
    • ItemBool
    • ItemString
    • ItemDouble
    • ItemUint64
  • A ItemData instance has the following information
    • ItemID (can be SYSTEM_ITEM_ID_ANONYMOUS)
    • Data type
    • Null flag
    • Value
    • Used count (derived from UsedCountable class)
  • Cannot modify the value once it is added to ItemGroup because it has ItemData as const. After that ItemData can be used multiple contexts on different threads.
  • An instance is typically wrapped by ItemDataPtr that is a smart pointer for ItemData and increments (decrements) the used count at the constructor (destructor).

ActionManager

  • Before newly obtained event data is passed to DBClientHatohol, it is compared with registered action conditions.
  • If the event meets any of the conditions, all of the corresponding actions are executed.
  • The execution process is asynchronous, so the caller thread may do the next task (typically saving the event to the DB) before the action finishes.
  • There are two kinds of actions.
    • Command
      • Simply executes a specified command or script.
      • The maximum number of command actions that can run concurrently: 10
        • If the number of actions exceeds the above limit, a new action are queued.
        • The queued action is executed soon after one of the running actions finishes.
    • Resident
      • Launched as a deamon process with a user specified shared library that contains the actual processing.
      • After that the same kind of matched event is notified to the daemon (resident) via PIPE.
      • Easily can use the previous action information or statistical information.
      • Lighter than the command type action that is launched on every matched event.
  • Automatically logs status of an action at several points and it is stored in DB via DBClientAction.
    • start, success, fail, queued.
    • failure reason
  • Currently (14.06), there is no interface to see action logs. (Users can see them with MySQL command line tools)
  • Methods of this class are called from various threads
    • ArmZabbixAPI, ArmNagiosNDOUtils, and HatoholArmPluginGate
      • execute an action if an event meets any conditions.
    • ChildProcessManager
      • Callback of the exit of actions.
      • In the callback, following things are performed.
        • Log the finish
        • execute a queued actions if it is
    • GLib's event loop
      • Timeout callback
        • Send KILL
      • Receive or error callback of NamedPipe (Resident type)
      • Deletion of related objects to avoid race.

IssueSenderManager and IssueSender

  • Registers an issue to indent management system via IssueSender.
  • Uses Action mechanism to check the condition.
  • See [here](Incident management system integration) for more information