...

Step 2 - Annotate stack configs (Non-UI Metadata) 

Each configuration that is used by the service's theme has to provide extra metadata about the configuration. The list of available metadata are: 

• display-name

• value-attributes

• type

• string

• value-list

• float

• int

• boolean

• minimum

• maximum

• unit

• increment-step

• entries

• entry

• value

• description

• depends-on

• property

• type

• name

...

Dependencies between configurations is a directed-acyclic-graph (DAG). When a configuration is updated, the UI has to determine its effect on other configs in the graph. To determine this, the /recommendations endpoint should be provided an array of what configurations have been just changed in the changed_configurations field. Based on the provided changed-configs, only its dependencies are updated in the response.

Example:

Figure below shows some config dependencies - A effects B and C, each of which effects DE and FG respectively.

Now assume user changes B to B' - a call to /recommendations will only change D and E to D' and E' respectively (AB'CD'E'FG). No other config will be changed. Now assume that C is changed to C' - /recommendations will only change F and G to F' and G' while still keeping the values of B' D' E' intact (AB'C'D'E'F'G'). Now if you change A to A', it will affect all its children (A'B''C''D''E''F''G''). The user will have chance to pick and choose which he wants to apply.

...

Step 3 - Restart Ambari server

...

Restarting ambari-server is required for any changes in the themes or the stack-definition to be loaded.

Reference

...

• HDFS HDP-2.2 theme.json

• YARN HDP-2.2 theme.json

• HIVE HDP-2.2 theme.json

Appendix

Appendix A - Widget Metadata Usage

<value-attributes>
  <type>int</type>
  <minimum>1073741824</minimum>
  <maximum>17179869184</maximum>
  <unit>B</unit>
  <increment-step>1073741824</increment-step>
</value-attributes>

<value-attributes>
  <type>value-list</type>
  <entries>
    <entry>
      <value>2</value>
    </entry>
    <entry>
      <value>4</value>
    </entry>
    <entry>
      <value>8</value>
    </entry>
  </entries>
  <selection-cardinality>1</selection-cardinality>
</value-attributes>