Dynamic UI definition specification

The main purpose of Dynamic UI is to generate application creation forms “on-the-fly”. The Murano dashboard does not know anything about applications that will be presented in the catalog and which web forms are required to create an application instance. So all application definitions should contain an instruction, which tells the dashboard how to create an application and what validations need to be applied. This document will help you to compose a valid UI definition for your application.

The UI definition should be a valid YAML file and may contain the following sections (for version 2.x):

  • Version

    Points out the syntax version in use. Optional

  • Templates

    An auxiliary section, used together with an Application section to help with object model composing. Optional

  • Parameters

    An auxiliary section for evaluated once parameters. Optional

  • ParametersSource

    A static action name (ClassName.methodName) to call for additional parameters. Optional

  • Application

    Object model description passed to murano engine and used for application deployment. Required

  • Forms

    Web form definitions. Required


The syntax and format of dynamic UI definitions may change over time, so the concept of format versions is introduced. Each UI definition file may contain a top-level section called Version to indicate the minimum version of Murano Dynamic UI platform which is capable to process it. If the section is missing, the format version is assumed to be latest supported.

The version consists of two non-negative integer segments, separated by a dot, i.e. has a form of MAJOR.MINOR. Dynamic UI platforms having the same MAJOR version component are compatible: i.e. the platform having the higher version may process UI definitions with lower versions if their MAJOR segments are the same. For example, Murano Dynamic UI platform of version 2.2 is able to process UI definitions of versions 2.0, 2.1 and 2.2, but is unable to process 3.0 or 1.9.

Currently, the latest version of Dynamic UI platform is 2.3. It is incompatible with UI definitions of Version 1.0, which were used in Murano releases before Juno.


Although the Version field is considered to be optional, its default value is the latest supported version. So if you intent to use applications with the previous stable murano version, verify that the version is set correctly.

Version history



OpenStack Version


  • Initial Dynamic UI implementation



  • instance field support is dropped

  • New Application section that describes engine object model

  • New Templates section for keeping reusable pieces of Object

Juno, Kilo


  • New network field provides a selection of networks and their subnetworks as a dropdown populated with those which are available to the current tenant.



  • Now application name is added automatically to the last service form. It is needed for a user to recognize one created application from another in the UI. Previously all application definitions contained the name property. So to support backward compatibility, you need to manually remove name field from class properties.



  • Now password field supports confirmInput flag and validator overloading with single regexpValidator or multiple validators attribute.



  • Parameters and ParametersSource sections were added

  • ref() YAQL function were added to Application DSL

  • YAQL expressions can be used anywhere in the form definition

  • choice control accepts choices in dictionary format



The Application section describes an application object model. The model is a dictionary (document) of application property values (inputs). Property value might be of any JSON-serializable type (including lists and maps). In addition the value can be of an object type (another application, application component, list of components etc.). Object properties are represented either by the object model of the component (i.e. dictionary) or by an object ID (string) if the object was already defined elsewhere. Each object definition (including the one in Application itself) must have a special ? key called object header. This key holds object metadata most important of which is the object type name. Thus the Application might look like this:

     type: "com.myCompany.myNamespace.MyClass"
  property1: "string property value"
  property2: 123
      key1: value1
      key2: [1, false, null]
       type: "com.myCompany.myNamespace.MyComponent"
    property: value

However in most cases the values in object model should come from input fields rather than being static as in example above. To achieve this, object model values can also be of a YAQL <https://opendev.org/openstack/yaql/src/branch/master/README.rst> expression type. With expressions language it becomes possible to retrieve input control values, do some calculations and data transformations (queries). Any YAML value that is not enclosed in quote marks and conforms to the YAQL syntax is considered to be a YAQL expression. There is also an explicit YAML tag for the YAQL expressions: !yaql.

So with the YAQL addition Application section might look like this:

     type: "com.myCompany.myNamespace.MyClass"
  property1: $.formName.controlName
  property2: 100 + 20 + 3
      !yaql "'KEY1'.toLower()'": !yaql "value1 + '1'"
      key2: [$parameter, not true]
  property4: null

When evaluating YAQL expressions $ is set to the forms data (list of dictionaries with cleaned validated forms’ data) and templates and parameters are available using $templateName ($parameterName) syntax. See below on templates and parameters.

YAQL comes with hundreds of functions bundled. In addition to that there are another four functions provided by murano dashboard:

  • generateHostname(pattern, index) is used for a machine hostname template generation. It accepts two arguments: name pattern (string) and index (integer). If ‘#’ symbol is present in name pattern, it will be replaced with the index provided. If pattern is an empty string, a random name will be generated.

  • repeat(template, times) is used to produce a list of data snippets, given the template snippet (first argument) and number of times it should be reproduced (second argument). Inside that template snippet current step can be referenced as $index.

  • name() returns current application name.

  • ref(templateName [, parameterName] [, idOnly]) is used to generate object definition from the template and then reference it several times in the object model. This function evaluates template templateName and fixes the result in parameters under parameterName key (or templateName if the second parameter was omitted). Then it generates object ID and places it into ?/id field. On the first use of parameterName or if idOnly is false the function will return the whole object structure. On subsequent calls or if idOnly is true it will return the ID that was generated upon the first call.


It is often that application object model contains number of similar instances of the same component/class. For example it might be list of servers for multi-server application or list of nodes or list of components. For such cases UI definition markup allow to give the repeated object model snippet a name and then refer to it by the name in the application object model. Such snippets are placed into Templates section:

       type: "io.murano.windows.activeDirectory.PrimaryController"
         type: "io.murano.windows.Host"
       adminPassword: $.appConfiguration.adminPassword
       name: generateHostname($.appConfiguration.unitNamingPattern, 1)
       flavor: $.instanceConfiguration.flavor
       image: $.instanceConfiguration.osImage

       type: "io.murano.windows.activeDirectory.SecondaryController"
         type: "io.murano.windows.Host"
       adminPassword: $.appConfiguration.adminPassword
       name: generateHostname($.appConfiguration.unitNamingPattern, $index + 1)
       flavor: $.instanceConfiguration.flavor
       image: $.instanceConfiguration.osImage

Then the template can be inserted into application object model or to another template using $templateName syntax. It is often case that it is used together with repeat function to put several instances of template. In this case templates may use of $index variable which will hold current iteration number:

    type: io.murano.windows.activeDirectory.ActiveDirectory
  primaryController: $primaryController
  secondaryControllers: repeat($secondaryController, $.appConfiguration.dcInstances - 1)

It is important to remember that templates are evaluated upon each access or repeat() iteration. Thus if the template has some properties set to a random or generated values they are going to be different for each instance of the template.

Another use case for templates is when single object is referenced several times within application object model:

       type: "io.murano.resources.LinuxMuranoInstance"
     image: myImage
     flavor: "m1.small"

    type: "com.example.MyApp"
    - ?:
        type: "com.example.MyComponentType1"
      instance: ref(instance)
    - ?:
        type: "com.example.MyComponentType2"
      instance: ref(instance)

In example above there are two components that uses the same server instance. If this example had $instance instead of ref(instance) that would be two unrelated servers based on the same template i.e. with the same image and flavor, but not the same VM.

Parameters and ParametersSource

Parameters are values that are used to parametrize the UI form and/or application object model. Parameters are put into Parameters section and accessed using $parameterName syntax:

  param1: "Hello!"

    type: "com.example.MyApp"
  stringProperty: $param1

Parameters are very similar to Templates with two differences:

  1. Parameter values are evaluated only once per application instance at the very beginning whereas templates are evaluated on each access.

  2. Parameter values can be used to initialize UI control attributes (e.g. initial text box value, list of choices for a drop down etc.)

However the most powerful feature about parameters is that their values might be obtained from the application class. Here is how to do it:

  1. In one of the classes in the MuranoPL package (usually the main application class define a static action method without arguments that returns a dictionary of variables:

    Name: "com.example.MyApp"
        Usage: Static
        Scope: Public
          # arbitrary MuranoPL code can be used here
            var1: value1
            var2: 123
  2. In UI definition file add
    ParametersSource: "com.example.MyApp.myMethod"

    The class name may be omitted. In this case the dashboard will try to use the type of Application object or package FQN for that purpose.

The values returned by the method are going to be merged into Parameters section like if they were defined statically.


This section describes markup elements for defining forms, which are currently rendered and validated with Django. Each form has a name, field definitions (mandatory), and validator definitions (optionally).

Note that each form is split into 2 parts:

  • input area - left side, where all the controls are located

  • description area - right side, where descriptions of the controls are located

Each field should contain:

  • name - system field name, could be any

  • type - system field type

Currently supported options for type attribute are:

  • string - text field (no inherent validations) with one-line text input

  • boolean - boolean field, rendered as a checkbox

  • text - same as string, but with a multi-line input

  • integer - integer field with an appropriate validation, one-line text input

  • choice - drop-down list of variants. Each variant has a display string that is going to be displayed to the user and associated key that is going to be a control value

  • password - text field with validation for strong password, rendered as two masked text inputs (second one is for password confirmation)

  • clusterip - specific text field, used for entering cluster IP address (validation for valid IP address syntax)

  • databaselist - specific field, a list of databases (comma-separated list of databases’ names, where each name has the following syntax first symbol should be latin letter or underscore; subsequent symbols can be latin letter, numeric, underscore, at the sign, number sign or dollar sign), rendered as one-line text input

  • image - specific field, used for filtering suitable images by image type provided in murano metadata in glance properties.

  • flavor - specific field, used for selection instance flavor from a list

  • keypair - specific field, used for selecting a keypair from a list

  • azone - specific field, used for selecting instance availability zone from a list

  • network - specific field, used to select a network and subnet from a list of the ones available to the current user

  • securitygroup - specific field, used for selecting a custom security group to assign to the instance

  • volume - specific field, used for selecting a volume or a volume snapshot from a list of available volumes (and volume snapshots)

  • any other value is considered to be a fully qualified name for some Application package and is rendered as a pair of controls: one for selecting already existing Applications of that type in an Environment, second - for creating a new Application of that type and selecting it

Other arguments (and whether they are required or not) depends on a field’s type and other attributes values. Most of them are standard Django field attributes. The most common attributes are the following:

  • label - name, that will be displayed in the form; defaults to name being capitalized.

  • description - description, that will be displayed in the description area. Use YAML line folding character >- to keep the correct formatting during data transferring.

  • descriptionTitle - title of the description, defaults to label; displayed in the description area

  • hidden whether field should be visible or not in the input area. Note that hidden field’s description will still be visible in the descriptions area (if given). Hidden fields are used storing some data to be used by other, visible fields.

  • minLength, maxLength (for string fields) and minValue, maxValue (for integer fields) are transparently translated into django validation properties.

  • choices - a choices for the choice control type. The format is [["key1", "display value1"], ["key2", "display value2"]]. Starting from version 2.4 this can also be passed as a {key1: "display value1", key2: "display value2"}

  • regexpValidator - regular expression to validate user input. Used with string or password field.

  • errorMessages - dictionary with optional ‘invalid’ and ‘required’ keys that set up what message to show to the user in case of errors.

  • validators is a list of dictionaries, each dictionary should at least have expr key, under that key either some YAQL expression is stored, either one-element dictionary with regexpValidator key (and some regexp string as value). Another possible key of a validator dictionary is message, and although it is not required, it is highly desirable to specify it - otherwise, when validator fails (i.e. regexp doesn’t match or YAQL expression evaluates to false) no message will be shown. Note that field-level validators use YAQL context different from all other attributes and section: here $ root object is set to the value of field being validated (to make expressions shorter).

    - name: someField
      type: string
      label: Domain Name
        - expr:
            regexpValidator: '(^[^.]+$|^[^.]{1,15}\..*$)'
          message: >-
               NetBIOS name cannot be shorter than 1 symbol and
               longer than 15 symbols.
        - expr:
           regexpValidator: '(^[^.]+$|^[^.]*\.[^.]{2,63}.*$)'
         message: >-
           DNS host name cannot be shorter than 2 symbols and
           longer than 63 symbols.
      helpText: >-
        Just letters, numbers and dashes are allowed.
        A dot can be used to create subdomains

    Using of regexpValidator and validators attributes with password field was introduced in version 2.3. By default, password should have at least 7 characters, 1 capital letter, 1 non-capital letter, 1 digit, and 1 special character. If you do not want password validation to be so strong, you can override it by setting a custom validator or multiple validators for password. For that add regexpValidator or validators to the password field and specify custom regexp string as value, just like with any string field.


    - name: password
      type: password
      label: Password
      descriptionTitle: Password
         description: >-
           Please, provide password for the application. Password should be
            5-50 characters long and consist of alphanumeric characters
      regexpValidator: '^[a-zA-Z0-9]{5,50}?$'
  • confirmInput is a flag used only with password field and defaults to true. If you decided to turn off automatic password field cloning, you should set it to false. In this case password confirmation is not required from a user.

  • widgetMedia sets some custom CSS and JavaScript used for the field’s widget rendering. Note, that files should be placed to Django static folder in advance. Mostly they are used to do some client-side field enabling/disabling, hiding/unhiding etc.

  • requirements is used only with flavor field and prevents user to pick unstable for a deployment flavor. It allows to set minimum ram (in MBs), disk space (in GBs) or virtual CPU quantity.

    Example that shows how to hide items smaller than regular small flavor in a flavor select field:

    - name: flavor
           type: flavor
           label: Instance flavor
               min_disk: 20
               min_vcpus: 2
               min_memory_mb: 2048
  • include_snapshots is used only with the volume field. True by default. If True, the field list includes available volumes and volume snapshots. If set to False, only available volumes are shown.

  • include_subnets is used only with network field. True by default. If True, the field list includes all the possible combinations of network and subnet. E.g. if there are two available networks X and Y, and X has two subnets A and B, while Y has a single subnet C, then the list will include 3 items: (X, A), (X, B), (Y, C). If set to False only network names will be listed, without their subnets.

  • filter is used only with network field. None by default. If set to a regexp string, will be used to display only the networks with names matching the given regexp.

  • murano_networks is used only with network field. None by default. May have values None, exclude or translate. Defines the handling of networks which are created by murano. Such networks usually have very long randomly generated names, and thus look ugly when displayed in the list. If this value is set to exclude then these networks are not shown in the list at all. If set to translate the names of such networks are replaced by a string Network of %env_name%.


    This functionality is based on the simple string matching of the network name prefix and the names of all the accessible murano environments. If the environment is renamed after the initial deployment this feature will not be able to properly translate or exclude its network name.

  • allow_auto is used only with network field. True by default. Defines if the default value of the dropdown (labeled “Auto”) should be present in the list. The default value is a tuple consisting of two None values. The logic on how to treat this value is up to application developer. It is suggested to use this field to indicate that the instance should join default environment network. For use-cases where such behavior is not desired, this parameter should be set to False.

Network field and its specific attributes (include_subnets, filter, murano_networks, allow_auto) are available since version 2.1. Before that, there was no way for the end user to select existing network in the UI. The only way to change the default networking behavior was the usage of networking.yaml file. It allows to override the networking setting at the environment level, for all the murano environments of all the tenants. Now you can simple add a network field to your form definition and provide the ability to select the desired network for the specific application.


- instanceConfiguration:
      - name: network
        type: network
        label: Network
        description: Select a network to join. 'Auto' corresponds to a default environment's network.
        murano_networks: translate

Besides field-level validators, form-level validators also exist. They use standard context for YAQL evaluation and are required when there is a need to validate some form’s constraint across several fields.


  - appConfiguration:
        - name: dcInstances
          type: integer
          hidden: true
          initial: 1
          required: false
          maxLength: 15
          helpText: Optional field for a machine hostname template
        - name: unitNamingPattern
          type: string
          label: Instance Naming Pattern
          required: false
          maxLength: 64
          regexpValidator: '^[a-zA-Z][-_\w]*$'
           invalid: Just letters, numbers, underscores and hyphens are allowed.
         helpText: Just letters, numbers, underscores and hyphens are allowed.
         description: >-
           Specify a string that will be used in a hostname instance.
           Just A-Z, a-z, 0-9, dash, and underline are allowed.

  - instanceConfiguration:
          - name: title
            type: string
            required: false
            hidden: true
            descriptionTitle: Instance Configuration
            description: Specify some instance parameters based on which service will be created.
          - name: flavor
            type: flavor
            label: Instance flavor
            description: >-
              Select a flavor registered in OpenStack. Consider that service performance
              depends on this parameter.
            required: false
          - name: osImage
            type: image
            imageType: windows
            label: Instance image
            description: >-
              Select valid image for a service. Image should already be prepared and
              registered in glance.
          - name: availabilityZone
            type: azone
            label: Availability zone
            description: Select an availability zone, where service will be installed.
            required: false
       # if unitNamingPattern is given and dcInstances > 1, then '#' should occur in unitNamingPattern
       - expr: $.appConfiguration.dcInstances < 2 or not $.appConfiguration.unitNamingPattern.bool()
               or '#' in $.appConfiguration.unitNamingPattern
         message: Incrementation symbol "#" is required in the Instance Naming Pattern

Control attributes might be initialized with a YAQL expression. However prior to version 2.4 it only worked for forms other than the first. It was designed to initialize controls with values input on the previous step. Starting with version 2.4 this limitation was removed and it become possible to use arbitrary YAQL expressions for any of control fields on any forms and use parameter values as part of these expressions.