Classes and Relationships¶

Classes and relationships form the model that forms the basis for everything Zenoss does. Classes are things like Device, FileSystem, IpInterface and OSProcess. Relationships state things like a Device contains many FileSystems. You will need to extend this model when the standard classes and relationships don’t adequately represent the model of a target your ZenPack is attempting to monitor. For example, a XenServer ZenPack needs to represent concepts like pools, storage repositories and virtual machines.

Standard Classes¶

The standard classes exist on all Zenoss systems. If these are the only types of things you care to model and monitor then you may not need to create your own classes or relationships.

Device
- DeviceHW (hw)
  - CPU (hw/cpus)
  - ExpansionCard (hw/cards)
  - Fan (hw/fans)
  - HardDisk (hw/harddisks)
  - PowerSupply (hw/powersupplies)
  - TemperatureSensor (hw/temperaturesensors)
- OperatingSystem (os)
  - FileSystem (os/filesystems)
  - IpInterface (os/interfaces)
  - IpRouteEntry (os/routes)
  - OSProcess (os/processes)
  - IpService (os/ipservices)
  - WinService (os/winservices)
  - Software (os/software)

Classes¶

If you need more than the standard classes provide, you will need to extend one of the following two base classes provided by zenpacklib.

zenpacklib.Device
zenpacklib.Component

You use zenpacklib.Device to create new device types of which instances will appear on the Infrastructure screen. You use zenpacklib.Component to create new component types of which instances will appear under Components on a device’s left navigation pane. Frequently when ZenPacks need to add new classes, they will add a single new device type with many new components types. For example, a XenServer ZenPack would add a new device type called Endpoint which represents the XenAPI management interface. That Endpoint device type would have many components of types such as Pool, StorageRepository and VirtualMachine.

Relationships¶

Relationships are Zenoss’ way of saying objects are related to each other. For example, the DeviceHW class contains many CPUs of the CPU class. You must also declare relationships between classes in your ZenPack. If you only declare types based on zenpacklib.Device you don’t have to do this because they’ll automatically have a relationship to their containing device class among other things. However, you must define at least a containing relationship for every type based on zenpacklib.Component you create. This is because components aren’t contained in any relationship by default, and every object in Zenoss must be contained somewhere.

zenpacklib supports the following types of relationships.

One-to-Many Containing (1:MC)
One-to-Many (1:M)
Many-to-Many (M:M)
One-to-One (1:1)

It’s important to understand the different between containing and non-containing relationships. Each component type must be contained by exactly one relationship. Beyond that a device or component type may have as many non- containing relationships as you like. This is because every object in Zenoss has a single primary path that describes where it is stored in the tree that is the Zenoss object database.

A simplified version of XenServer’s classes and relationships provides for a good example. The following list of relationship states the following: An endpoint contains zero or more pools, each pool contains zero or more storage repositories and virtual machines, and each storage repository is related to zero or more virtual machines.

Endpoint 1:MC Pool
Pool 1:MC StorageRepository
Pool 1:MC VirtualMachine
StorageRepository M:M VirtualMachine

Adding Classes and Relationships¶

To add classes and relationships to zenpack.yaml you add entries to the top-level classes and class_relationships fields. The following example shows a XenServer Endpoint device type along with Pool, StorageRepository, and VirtualMachine component types.

name: ZenPacks.example.XenServer

classes:
  DEFAULTS:
    base: [zenpacklib.Component]

  XenServerEndpoint:
    base: [zenpacklib.Device]
    label: Endpoint

  XenServerPool:
    label: Pool

    properties:
      ha_enabled:
        type: boolean
        label: HA Enabled
        short_label: HA

      ha_allow_overcommit:
        type: boolean
        label: HA Allow Overcommit
        short_label: Overcommit

  XenServerStorageRepository:
    label: Storage Repository

    properties:
      physical_size:
        type: int
        label: Physical Size
        short_label: Size

  XenServerVirtualMachine:
    label: Virtual Machine

    properties:
      vcpus_at_startup:
        type: int
        label: vCPUs at Startup
        short_label: vCPUs

class_relationships:
  - XenServerEndpoint 1:MC XenServerPool
  - XenServerPool 1:MC XenServerStorageRepository
  - XenServerPool 1:MC XenServerVirtualMachine
  - XenServerStorageRepository M:M XenServerVirtualMachine

Note

DEFAULTS can be used in classes just like in zProperties to avoid repetitively setting the same field for many entries. Note specifically how XenServerPool, XenServerStorageRepository and XenServerVirtualMachine will inherit the default while XenServerEndpoint overrides it.

Classes and their properties allow for a wide range of control. See the following section for details.

Class Fields¶

The following fields are valid for a class entry.

name

Description:	Name (e.g. XenServerEndpoint). Must be a valid Python class name.
Required:	Yes
Type:	string
Default Value:	(implied from key in classes map)

base

Description:	List of base classes to extend.
Required:	No
Type:	list<classname>
Default Value:	[zenpacklib.Component]

meta_type

Description:	Globally unique name for the class.
Required:	No
Type:	string
Default Value:	(same as name)

label

Description:	Human-friendly label for the class.
Required:	No
Type:	string
Default Value:	(same as meta_type)

plural_label

Description:	Plural form of label.
Required:	No
Type:	string
Default Value:	(same as label with an “s” suffix)

short_label

Description:	Short form of label. Used as a column header or where space is limited.
Required:	No
Type:	string
Default Value:	(same as label)

plural_short_label

Description:	Plural form of short_label.
Required:	No
Type:	string
Default Value:	(same as short_label with an “s” suffix)

icon

Description:	Filename (in resources/) for icon.
Required:	No
Type:	string
Default Value:	(same as name with a ”.png” suffix)

label_width

Description:	Width of label text in pixels.
Required:	No
Type:	integer
Default Value:	80

plural_label_width

Description:	Width of plural_label text in pixels.
Required:	No
Type:	integer
Default Value:	(same as label_width + 7)

content_width

Description:	Expected width of object’s title in pixels.
Required:	No
Type:	integer
Default Value:	(same as label_width)

auto_expand_column

Description:	Column (property) to auto-expand in component grid.
Required:	No
Type:	string
Default Value:	name

order

Description:	Order to display this class among other classes. (0-100)
Required:	No
Type:	integer
Default Value:	50

filter_display

Description:	Will related components be filterable by components of this type?
Required:	No
Type:	boolean
Default Value:	true

filter_hide_from

Description:	Classes for which this class should not show in the filter dropdown.
Required:	No
Type:	list<classname>
Default Value:	[] (empty list)

monitoring_templates

Description:	List of monitoring template names to bind to components of this type.
Required:	No
Type:	list<string>
Default Value:	[(label with spaces removed)]

properties

Description:	Properties for this class.
Required:	No
Type:	map<name, Class Property>
Default Value:	{} (empty map)

relationships

Description:	Relationship overrides for this class.
Required:	No
Type:	map<name, Relationship Override>
Default Value:	{} (empty map)

impacts

Description:	Relationship or method names that when called return a list of objects that objects of this class could impact.
Required:	No
Type:	list<relationship_or_method_name>
Default Value:	[] (empty list)

impacted_by

Description:	Relationship or method names that when called return a list of objects that could impact objects of this class.
Required:	No
Type:	list<relationship_or_method_name>
Default Value:	[] (empty list)

dynamicview_views

Description:	Names of Dynamic Views objects of this class can appear in.
Required:	No
Type:	list<dynamicview_view_name>
Default Value:	[] (empty list)

dynamicview_groups

Description:	Dynamic View group name for objects of this class.
Required:	No
Type:	string
Default Value:	(same as plural_short_label)

dynamicview_relations

Description:	Map of Dynamic View relationships for this class and the relationship or method names that when called populate them.
Required:	No
Type:	map<relationship_name, list<relationship_or_method_name>>
Default Value:	{} (empty map)

extra_paths

Description:	By default, components are indexed based upon paths that include objects they have a direct relationship to. This option allows additional paths to be specified (this can be useful when indirect containment is used)
Required:	No
Type:	list<list<regexp>>
Default Value:	[] (empty list)

Class Property Fields¶

The following fields are valid for a class property entry.

name

Description:	Name (e.g. ha_enabled). Must be a valid Python variable name.
Required:	Yes
Type:	string
Default Value:	(implied from key in properties map)

type

Description:	Type of property: string, int, float, boolean, lines, password or entity.
Required:	No
Type:	string
Default Value:	string

default

Description:	Default value for property.
Required:	No
Type:	(varies depending on type)
Default Value:	None

label

Description:	Human-friendly label for the property.
Required:	No
Type:	string
Default Value:	(same as name)

short_label

Description:	Short form of label. Used as a column header where space is limited.
Required:	No
Type:	string
Default Value:	(same as label)

label_width

Description:	Width of label text in pixels.
Required:	No
Type:	integer
Default Value:	80

content_width

Description:	Expected width of property’s value in pixels.
Required:	No
Type:	integer
Default Value:	(same as label_width)

display

Description:	Should this property be shown as a column and in details?
Required:	No
Type:	boolean
Default Value:	true

details_display

Description:	Should this property be shown in details?
Required:	No
Type:	boolean
Default Value:	true

grid_display

Description:	Should this property be shown as a column?
Required:	No
Type:	boolean
Default Value:	true

order

Description:	Order to display this property among other properties. (0-100)
Required:	No
Type:	integer
Default Value:	45

editable

Description:	Should this property be editable in details?
Required:	No
Type:	boolean
Default Value:	false

renderer

Description:	JavaScript renderer for property value.
Required:	No
Type:	string
Default Value:	None (renders value as-is)

api_only

Description:	Should this property be for the API only? The property or method (according to api_backendtype) must be manually implemented if this is set to true.
Required:	No
Type:	boolean
Default Value:	false

api_backendtype

Description:	Implementation style for the property if api_only is true. Must be property or method.
Required:	No
Type:	string
Default Value:	property

enum

Description:	Enumeration map for property. Set to something like {1: ‘OK’, 2: ‘ERROR’} for an int-type property to provide text representations for property values.
Required:	No
Type:	map<value, representation>
Default Value:	{} (empty map)

datapoint

Description:	datasource_datapoint value to use as the value for this property. Useful for displaying the most recent collected datapoint value in the grid or details as any modeled property would be.
Required:	No
Type:	string
Default Value:	None

datapoint_default

Description:	Default value for property if datapoint is set, but no data exists.
Required:	No
Type:	string, integer or float
Default Value:	None

datapoint_cached

Description:	Should the value for datapoint be cached for a limited time? Can improve UI performance.
Required:	No
Type:	boolean
Default Value:	true

index_type

Description:	Type of indexing for the property: field or keyword.
Required:	No
Type:	string
Default Value:	None (no indexing)

index_scope

Description:	Scope of index: device or global. Only applies if index_type is set.
Required:	No
Type:	string
Default Value:	device

Relationship Override Fields¶

The following fields are valid for a relationship override entry.

name

Description:	Name (e.g. xenServerPools). Must match a relationship name defined in class_relationships.
Required:	Yes
Type:	string
Default Value:	(implied from key in relationships map)

label

Description:	Human-friendly label for the relationship.
Required:	No
Type:	string
Default Value:	(label of class to which the relationship refers)

short_label

Description:	Short form of label. Used as a column header where space is limited.
Required:	No
Type:	string
Default Value:	(same as label or referred class’ short_label)

label_width

Description:	Width of label text in pixels.
Required:	No
Type:	integer
Default Value:	(same as referred class’ label width)

content_width

Description:	Expected width of relationship’s value in pixels. To-Many relationships are shown simply as a count and will have a shorter width. To-One relationships show a link to the object and will require a width long enough to accommodate the object’s title.
Required:	No
Type:	integer
Default Value:	(varies depending on relationship type)

display

Description:	Should this relationship be shown as a column and in details?
Required:	No
Type:	boolean
Default Value:	true

details_display

Description:	Should this relationship be shown in details?
Required:	No
Type:	boolean
Default Value:	true

grid_display

Description:	Should this relationship be shown as a column?
Required:	No
Type:	boolean
Default Value:	true

order

Description:	Order to display this relationship among other relationships and properties. (0-10)
Required:	No
Type:	float
Default Value:	3.0 for To-One, 6.0 for To-Many.

renderer

Description:	JavaScript renderer for relationship value.
Required:	No
Type:	string
Default Value:	None

render_with_type

Description:	Should related object be rendered with it’s type? Only applies to To-One relationships.
Required:	No
Type:	boolean
Default Value:	false