Extending OpenStack Settings

Extending OpenStack Settings

Each release has a list of OpenStack settings that can be customized. The settings configuration is stored in the “attributes_metadata.editable” release section in the openstack.yaml file.

Settings are divided into groups. Each group should have a “metadata” section with the following attributes:

  toggleable: true
  enabled: false
  weight: 40
  • toggleable defines an ability to enable/disable the whole setting group on UI (checkbox control is presented near a setting group label)
  • enabled indicates whether the group is checked on the UI
  • weight defines the order in which this group is displayed on the tab.
  • restrictions: see restrictions.

Other sections of a setting group represent separate settings. A setting structure includes the following attributes:

  value: "tcp"
  label: "Syslog transport protocol"
  description: ""
  weight: 30
  type: "radio"
    - data: "udp"
      label: "UDP"
      description: ""
        - "cluster:net_provider != 'neutron'"
    - data: "tcp"
      label: "TCP"
      description: ""
    source: "^[A-z0-9]+$"
    error: "Invalid data"
  min: 1
  max: 3
  • label is a setting title that is displayed on UI
  • weight defines the order in which this setting is displayed in its group. This attribute is desirable
  • type defines the type of UI control to use for the setting. The following types are supported:
    • text - single line input
    • number - number input
    • password - password input
    • textarea - multiline input
    • checkbox - multiple-options selector
    • radio - single-option selector
    • select - drop-down list
    • hidden - invisible input
    • file - file contents input
    • text_list - multiple sigle line text inputs
    • textarea_list - multiple multiline text inputs
  • regex section is applicable for settings of “text” type. “regex.source” is used when validating with a regular expression. “regex.error” contains a warning displayed near invalid field
  • restrictions: see restrictions.
  • description section should also contain information about setting restrictions (dependencies, conflicts)
  • values list is needed for settings of “radio” or “select” type to declare its possible values. Options from “values” list also support dependencies and conflcits declaration.
  • min is used for setting the “number”, “text_list” or “textarea_list” type. For the “number” type, “min” declares the minimum input number value. For the “text_list” and “textarea_list” types, it declares the minimum list length for the setting.
  • max is used for setting the “number”, “text_list”, or “textarea_list” type. For the “number” type, “max” declares the maximum input number value. For the “text_list” and “textarea_list” types, it declares the maximum list length for the setting.


Restrictions define when settings and setting groups should be available. Each restriction is defined as a condition with optional action, message and strict:

  - condition: "settings:common.libvirt_type.value != 'kvm'"
    message: "KVM only is supported"
  - condition: "not ('experimental' in version:feature_groups)"
    action: hide
  • condition is an expression written in Expression DSL. If returned value is true, then action is performed and message is shown (if specified).

  • action defines what to do if condition is satisfied. Supported values are “disable”, “hide” and “none”. “none” can be used just to display message. This field is optional (default value is “disable”).

  • message is a message that is shown if condition is satisfied. This field is optional.

  • strict is a boolean flag which specifies how to handle non-existent keys in expressions. If it is set to true (default value), exception is thrown in case of non-existent key. Otherwise values of such keys have null value. Setting this flag to false is useful for conditions which rely on settings provided by plugins:

      - condition: "settings:other_plugin == null or settings:other_plugin.metadata.enabled != true"
        strict: false
        message: "Other plugin must be installed and enabled"

There are also short forms of restrictions:

  - "settings:common.libvirt_type.value != 'kvm'": "KVM only is supported"
  - "settings:storage.volumes_ceph.value == true"

Expression Syntax

Expression DSL can describe arbitrarily complex conditions that compare fields of models and scalar values.

Supported types are:

  • Number (123, 5.67)
  • String (“qwe”, ‘zxc’)
  • Boolean (true, false)
  • Null value (null)
  • ModelPath (settings:common.libvirt_type.value, cluster:net_provider)

ModelPaths consist of a model name and a field name separated by ”:”. Nested fields (like in settings) are supported, separated by ”.”. Models available for usage are “cluster”, “settings”, “networking_parameters” and “version”.

Supported operators are:

  • “==”. Returns true if operands are equal:

    settings:common.libvirt_type.value == 'qemu'
  • ”!=”. Returns true if operands are not equal:

    cluster:net_provider != 'neutron'
  • “in”. Returns true if the right operand (Array or String) contains the left operand:

    'ceph-osd' in release:roles
  • Boolean operators: “and”, “or”, “not”:

    cluster:mode == "ha_compact" and not (settings:common.libvirt_type.value == 'kvm' or 'experimental' in version:feature_groups)

Parentheses can be used to override the order of precedence.

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