Monitor Plugin

Version: 1.0

Status:

Monitor plugin for Thunder framework.

Introduction

Scope

This document describes purpose and functionality of the Monitor plugin. It includes detailed specification about its configuration, methods and properties as well as sent notifications.

Case Sensitivity

All identifiers of the interfaces described in this document are case-sensitive. Thus, unless stated otherwise, all keywords, entities, properties, relations and actions should be treated as such.

Acronyms, Abbreviations and Terms

The table below provides and overview of acronyms used in this document and their definitions.

Acronym	Description
API	Application Programming Interface
HTTP	Hypertext Transfer Protocol
JSON	JavaScript Object Notation; a data interchange format
JSON-RPC	A remote procedure call protocol encoded in JSON

The table below provides and overview of terms and abbreviations used in this document and their definitions.

Term	Description
callsign	The name given to an instance of a plugin. One plugin can be instantiated multiple times, but each instance the instance name, callsign, must be unique.

References

Ref ID	Description
HTTP	HTTP specification
JSON-RPC	JSON-RPC 2.0 specification
JSON	JSON specification
Thunder	Thunder API Reference

Description

The Monitor plugin provides a watchdog-like functionality for framework processes.

The plugin is designed to be loaded and executed within the Thunder framework. For more information about the framework refer to [Thunder].

Configuration

The table below lists configuration options of the plugin.

Name	Type	M/O	Description
callsign	string	mandatory	Plugin instance name (default: Monitor)
classname	string	mandatory	Class name: Monitor
locator	string	mandatory	Library name: libThunderMonitor.so
startmode	string	mandatory	Determines in which state the plugin should be moved to at startup of the framework
configuration	object	optional	...
configuration?.observables	array	optional	List of observable plugin details
configuration?.observables[#]	object	mandatory	...
configuration?.observables[#]?.callsign	string	optional	Callsign of the plugin to be monitored
configuration?.observables[#]?.memory	integer	optional	Interval(in seconds) for a memory measurement
configuration?.observables[#]?.memorylimit	integer	optional	Memory threshold in bytes
configuration?.observables[#]?.operational	integer	optional	Interval(in seconds) to check the monitored processes
configuration?.observables[#]?.restart	object	optional	Restart limits for failures applying to the plugin
configuration?.observables[#]?.restart?.window	integer	optional	Time period(in seconds) within which failures must happen for the limit to be considered crossed
configuration?.observables[#]?.restart?.limit	integer	optional	Maximum number or restarts to be attempted

Interfaces

This plugin implements the following interfaces:

Monitor.json (version 1.0.0) (compliant format)
IMemoryMonitor (IMemoryMonitor.h) (version 1.0.0) (compliant format)

This interface uses legacy lowercase naming convention. With the next major release the naming convention will change to camelCase.

Methods

The following methods are provided by the Monitor plugin:

Monitor interface methods:

Method	Description
restartlimits	Sets new restart limits for a service
resetstats	Resets memory and process statistics for a single service watched by the Monitor

MemoryMonitor interface methods:

Method	Description
resetstatistics	Resets memory statistics for a given service

restartlimits ^method

Sets new restart limits for a service.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.callsign	string	mandatory	The callsign of a service to reset measurements snapshot of
params.restart	object	mandatory	Restart limits for failures applying to the service
params.restart.limit	integer	mandatory	Maximum number or restarts to be attempted
params.restart.window	integer	mandatory	Time period (in seconds) within which failures must happen for the limit to be considered crossed

Result

Name	Type	M/O	Description
result	null	mandatory	Always null (default: None)

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.restartlimits",
  "params": {
    "callsign": "WebServer",
    "restart": {
      "limit": 3,
      "window": 60
    }
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

resetstats ^method

Resets memory and process statistics for a single service watched by the Monitor.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.callsign	string	mandatory	The callsign of a service to reset statistics of

Result

Name	Type	M/O	Description
result	object	mandatory	Measurements for the service before reset
result.measurements	object	mandatory	Measurements for the service
result.measurements.resident	object	mandatory	Resident memory measurement
result.measurements.resident.min	integer	mandatory	Minimal value measured
result.measurements.resident.max	integer	mandatory	Maximal value measured
result.measurements.resident.average	integer	mandatory	Average of all measurements
result.measurements.resident.last	integer	mandatory	Last measured value
result.measurements.allocated	object	mandatory	Allocated memory measurement
result.measurements.allocated.min	integer	mandatory	Minimal value measured
result.measurements.allocated.max	integer	mandatory	Maximal value measured
result.measurements.allocated.average	integer	mandatory	Average of all measurements
result.measurements.allocated.last	integer	mandatory	Last measured value
result.measurements.shared	object	mandatory	Shared memory measurement
result.measurements.shared.min	integer	mandatory	Minimal value measured
result.measurements.shared.max	integer	mandatory	Maximal value measured
result.measurements.shared.average	integer	mandatory	Average of all measurements
result.measurements.shared.last	integer	mandatory	Last measured value
result.measurements.process	object	mandatory	Processes measurement
result.measurements.process.min	integer	mandatory	Minimal value measured
result.measurements.process.max	integer	mandatory	Maximal value measured
result.measurements.process.average	integer	mandatory	Average of all measurements
result.measurements.process.last	integer	mandatory	Last measured value
result.measurements.operational	boolean	mandatory	Whether the service is up and running
result.measurements.count	integer	mandatory	Number of measurements
result.observable	string	mandatory	A callsign of the watched service
result.restart	object	mandatory	Restart limits for failures applying to the service
result.restart.limit	integer	mandatory	Maximum number or restarts to be attempted
result.restart.window	integer	mandatory	Time period (in seconds) within which failures must happen for the limit to be considered crossed

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.resetstats",
  "params": {
    "callsign": "WebServer"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": {
    "measurements": {
      "resident": {
        "min": 0,
        "max": 100,
        "average": 50,
        "last": 100
      },
      "allocated": {
        "min": 0,
        "max": 100,
        "average": 50,
        "last": 100
      },
      "shared": {
        "min": 0,
        "max": 100,
        "average": 50,
        "last": 100
      },
      "process": {
        "min": 0,
        "max": 100,
        "average": 50,
        "last": 100
      },
      "operational": true,
      "count": 100
    },
    "observable": "callsign",
    "restart": {
      "limit": 3,
      "window": 60
    }
  }
}

resetstatistics ^method

Resets memory statistics for a given service.

Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.callsign	string	mandatory	Callsign of the service

Result

Name	Type	M/O	Description
result	null	mandatory	Always null

Example

Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.resetstatistics",
  "params": {
    "callsign": "WebServer"
  }
}

Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": null
}

Properties

The following properties are provided by the Monitor plugin:

Monitor interface properties:

Property	R/W	Description
status	read-only	Service statistics

MemoryMonitor interface properties:

Property	R/W	Description
restartinglimits	read/write	Limits of restarting of a service
observables	read-only	List of services watched by the Monitor
measurementdata	read-only	Memory statistics for a given service

status ^property

Provides access to the service statistics.

This property is read-only.

The callsign parameter shall be passed as the index to the property, i.e. status@<callsign>.

Index

Name	Type	M/O	Description
callsign	string	mandatory	If omitted then all observed objects will be returned on read

Value

Name	Type	M/O	Description
(property)	array	mandatory	Service statistics
(property)[#]	object	mandatory	...
(property)[#].measurements	object	mandatory	Measurements for the service
(property)[#].measurements.resident	object	mandatory	Resident memory measurement
(property)[#].measurements.resident.min	integer	mandatory	Minimal value measured
(property)[#].measurements.resident.max	integer	mandatory	Maximal value measured
(property)[#].measurements.resident.average	integer	mandatory	Average of all measurements
(property)[#].measurements.resident.last	integer	mandatory	Last measured value
(property)[#].measurements.allocated	object	mandatory	Allocated memory measurement
(property)[#].measurements.allocated.min	integer	mandatory	Minimal value measured
(property)[#].measurements.allocated.max	integer	mandatory	Maximal value measured
(property)[#].measurements.allocated.average	integer	mandatory	Average of all measurements
(property)[#].measurements.allocated.last	integer	mandatory	Last measured value
(property)[#].measurements.shared	object	mandatory	Shared memory measurement
(property)[#].measurements.shared.min	integer	mandatory	Minimal value measured
(property)[#].measurements.shared.max	integer	mandatory	Maximal value measured
(property)[#].measurements.shared.average	integer	mandatory	Average of all measurements
(property)[#].measurements.shared.last	integer	mandatory	Last measured value
(property)[#].measurements.process	object	mandatory	Processes measurement
(property)[#].measurements.process.min	integer	mandatory	Minimal value measured
(property)[#].measurements.process.max	integer	mandatory	Maximal value measured
(property)[#].measurements.process.average	integer	mandatory	Average of all measurements
(property)[#].measurements.process.last	integer	mandatory	Last measured value
(property)[#].measurements.operational	boolean	mandatory	Whether the service is up and running
(property)[#].measurements.count	integer	mandatory	Number of measurements
(property)[#].observable	string	mandatory	A callsign of the watched service
(property)[#].restart	object	mandatory	Restart limits for failures applying to the service
(property)[#].restart.limit	integer	mandatory	Maximum number or restarts to be attempted
(property)[#].restart.window	integer	mandatory	Time period (in seconds) within which failures must happen for the limit to be considered crossed

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.status@WebServer"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": [
    {
      "measurements": {
        "resident": {
          "min": 0,
          "max": 100,
          "average": 50,
          "last": 100
        },
        "allocated": {
          "min": 0,
          "max": 100,
          "average": 50,
          "last": 100
        },
        "shared": {
          "min": 0,
          "max": 100,
          "average": 50,
          "last": 100
        },
        "process": {
          "min": 0,
          "max": 100,
          "average": 50,
          "last": 100
        },
        "operational": true,
        "count": 100
      },
      "observable": "callsign",
      "restart": {
        "limit": 3,
        "window": 60
      }
    }
  ]
}

restartinglimits ^property

Provides access to the limits of restarting of a service.

The callsign parameter shall be passed as the index to the property, i.e. restartinglimits@<callsign>.

Index (Get)

Name	Type	M/O	Description
callsign	string	mandatory	Callsign of the service

Index (Set)

Name	Type	M/O	Description
callsign	string	mandatory	Callsign of the service

Value

Name	Type	M/O	Description
(property)	object	mandatory	Limits of restarting of a service
(property).value	object	mandatory	Limits of restarts applying to a given service
(property).value.limit	integer	mandatory	Maximum number or restarts to be attempted
(property).value.window	integer	mandatory	Time period (in seconds) within which failures must happen for the limit to be considered crossed

Name	Type	M/O	Description
(property)	object	mandatory	Limits of restarting of a service
(property).limit	integer	mandatory	Maximum number or restarts to be attempted
(property).window	integer	mandatory	Time period (in seconds) within which failures must happen for the limit to be considered crossed

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.restartinglimits@WebServer"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": {
    "limit": 3,
    "window": 60
  }
}

Set Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.restartinglimits@WebServer",
  "params": {
    "value": {
      "limit": 3,
      "window": 60
    }
  }
}

Set Response

{
    "jsonrpc": "2.0",
    "id": 42,
    "result": "null"
}

observables ^property

Provides access to the list of services watched by the Monitor.

This property is read-only.

Value

Name	Type	M/O	Description
(property)	array	mandatory	List of monitored services
(property)[#]	string	mandatory	...

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.observables"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": [
    "..."
  ]
}

measurementdata ^property

Provides access to the memory statistics for a given service.

This property is read-only.

The callsign parameter shall be passed as the index to the property, i.e. measurementdata@<callsign>.

Index

Name	Type	M/O	Description
callsign	string	mandatory	Callsign of the service

Value

Name	Type	M/O	Description
(property)	object	mandatory	Statistics for the requested callsign
(property).resident	object	mandatory	Resident memory measurement
(property).resident.min	integer	mandatory	Minimal value measured
(property).resident.max	integer	mandatory	Maximal value measured
(property).resident.average	integer	mandatory	Average of all measurements
(property).resident.last	integer	mandatory	Last measured value
(property).allocated	object	mandatory	Allocated memory measurement
(property).allocated.min	integer	mandatory	Minimal value measured
(property).allocated.max	integer	mandatory	Maximal value measured
(property).allocated.average	integer	mandatory	Average of all measurements
(property).allocated.last	integer	mandatory	Last measured value
(property).shared	object	mandatory	Shared memory measurement
(property).shared.min	integer	mandatory	Minimal value measured
(property).shared.max	integer	mandatory	Maximal value measured
(property).shared.average	integer	mandatory	Average of all measurements
(property).shared.last	integer	mandatory	Last measured value
(property).process	object	mandatory	Processes measurement
(property).process.min	integer	mandatory	Minimal value measured
(property).process.max	integer	mandatory	Maximal value measured
(property).process.average	integer	mandatory	Average of all measurements
(property).process.last	integer	mandatory	Last measured value
(property).operational	boolean	mandatory	Whether the service is up and running
(property).count	integer	mandatory	Number of measurements

Example

Get Request

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.measurementdata@WebServer"
}

Get Response

{
  "jsonrpc": "2.0",
  "id": 42,
  "result": {
    "resident": {
      "min": 0,
      "max": 100,
      "average": 50,
      "last": 100
    },
    "allocated": {
      "min": 0,
      "max": 100,
      "average": 50,
      "last": 100
    },
    "shared": {
      "min": 0,
      "max": 100,
      "average": 50,
      "last": 100
    },
    "process": {
      "min": 0,
      "max": 100,
      "average": 50,
      "last": 100
    },
    "operational": true,
    "count": 100
  }
}

Notifications

Notifications are autonomous events triggered by the internals of the implementation and broadcasted via JSON-RPC to all registered observers. Refer to [Thunder] for information on how to register for a notification.

The following events are provided by the Monitor plugin:

Monitor interface events:

Notification	Description
action	Signals an action taken by the Monitor

MemoryMonitor interface events:

Notification	Description
statuschanged	Signals an action taken by the Monitor

action ^notification

Signals an action taken by the Monitor.

Notification Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.callsign	string	mandatory	Callsign of the service the Monitor acted upon
params.action	string	mandatory	The action executed by the Monitor on a service. One of: "Activate", "Deactivate", "StoppedRestarting"
params.reason	string	mandatory	A message describing the reason the action was taken

Example

Registration

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.register",
  "params": {
    "event": "action",
    "id": "myid"
  }
}

Notification

{
  "jsonrpc": "2.0",
  "method": "myid.action",
  "params": {
    "callsign": "WebServer",
    "action": "Deactivate",
    "reason": "EXCEEDED_MEMORY"
  }
}

The client ID parameter is passed within the notification designator, i.e. <client-id>.action.

statuschanged ^notification

Signals an action taken by the Monitor.

Notification Parameters

Name	Type	M/O	Description
params	object	mandatory	...
params.callsign	string	mandatory	Callsign of the service the Monitor acted upon
params.action	string	mandatory	Ation executed by the Monitor on a service (must be one of the following: Activated, Deactivated, RestartingStopped)
params?.reason	string	optional	Mssage describing the reason the action was taken (must be one of the following: ExceededMemory, NotOperational)

Example

Registration

{
  "jsonrpc": "2.0",
  "id": 42,
  "method": "Monitor.1.register",
  "params": {
    "event": "statuschanged",
    "id": "myid"
  }
}

Notification

{
  "jsonrpc": "2.0",
  "method": "myid.statuschanged",
  "params": {
    "callsign": "WebServer",
    "action": "Deactivate",
    "reason": "EXCEEDED_MEMORY"
  }
}

The client ID parameter is passed within the notification designator, i.e. <client-id>.statuschanged.

Monitor Plugin

Table of Contents

Introduction

Scope

Case Sensitivity

Acronyms, Abbreviations and Terms

References

Description

Configuration

Interfaces

Methods

restartlimits method

Parameters

Result

Example

Request

Response

resetstats method

Parameters

Result

Example

Request

Response

resetstatistics method

Parameters

Result

Example

Request

Response

Properties

status property

Index

Value

Example

Get Request

Get Response

restartinglimits property

Index (Get)

Index (Set)

Value

Example

Get Request

Get Response

Set Request

Set Response

observables property

Value

Example

Get Request

Get Response

measurementdata property

Index

Value

Example

Get Request

Get Response

Notifications

action notification

Notification Parameters

Example

Registration

Notification

statuschanged notification

Notification Parameters

Example

Registration

Notification

restartlimits ^method

resetstats ^method

resetstatistics ^method

status ^property

restartinglimits ^property

observables ^property

measurementdata ^property

action ^notification

statuschanged ^notification