Cloudera Docs

Using parameters in Cloudera Edge Management

Learn how to reference or create parameters as you configure the components in your flow to enhance flow configuration and management.

Referencing existing parameters

Existing parameters can be referenced for a processor or service property value during configuration.
  1. To reference an existing parameter, select the property value field and clear the default value if one exists.
  2. Enter the start delimiter #{.


  3. Enter the parameter name, or press Control+Space to view the list of available parameters.


  4. Complete the reference with a closing curly brace } and select Ok.


  5. Click Apply to save the changes.
    You can hover over the Expression Language and Parameters indicators for help text on this process.


Converting property values to parameters

You can create parameters during the configuration of processors or services. Instead of entering a property value, you can convert the property value to a parameter.
  1. Click (the Convert to parameter icon) for the chosen property.


    The Create Parameter modal window appears.


  2. Configure the parameter properties.
  3. Click Add to create the parameter.

    The property will automatically reference the new parameter using the correct syntax.



  4. Click Apply to save the changes.

Converting selectable property values to parameters

Property values that are selectable can also reference parameters.
  1. Select the property value drop-down. The option Reference parameter... is available for eligible properties.


  2. Select Reference parameter… option. A list of parameters to choose appears.


  3. Select a parameter and click OK.
  4. Click Apply to save the changes.

Using parameters in expressions

Parameters can be referenced using the #{} syntax, with options for escaping and combining parameters.

To configure an eligible property to reference a parameter, use the # symbol as the start, with the name of the parameter enclosed in curly braces.

#{Parameter.Name}

If needed, escape the # using an additional # at the beginning.

Examples

If parameter abc has a value of xxx and parameter def has a value of yyy, the following user-defined property values will evaluate to these effective values:

User-Entered Literal Property Value Effective Property Value Explanation
#{abc} xxx Simple substitution
#{abc}/data xxx/data Simple substitution with additional literal data
#{abc}/#{def} xxx/yyy Multiple substitution with additional literal data
#{abc #{abc No { } for parameter replacement
#abc #abc No { } for parameter replacement
##{abc} #{abc} Escaped # for literal interpretation
###{abc} #xxx Escaped # for literal interpretation, followed by simple substitution
####{abc} ##{abc} Escaped # for literal interpretation, twice
#####{abc} ##xxx Escaped # for literal interpretation, twice, followed by simple substitution
#{abc/data} Exception thrown on property set operation / not a valid parameter name character

When referencing a parameter from within expression language, the parameter reference is evaluated first.

For example:
${ #{abc}:replace('xxx', 'zzz') }

This replaces xxx with zzz for the abc parameter.

Referenced parameters

The Parameters window lists all parameters used in a flow, along with the components that reference them.



Select a specific parameter to view the processors and services that use it.

Using parameters with sensitive properties

Non-sensitive properties should only be referenced by non-sensitive parameters, and sensitive properties should only be referenced by sensitive parameters.

When publishing versioned flows:

  • The value of a sensitive parameter is not sent to the flow registry, only the information that the property references the sensitive parameter.
  • If a non-sensitive property references a sensitive parameter (or the other way round), the UI marks the component as invalid.