Parameter Types

YAML Types

Many of the types we use in this profile are built-in types from the YAML 1.2 specification (i.e., those identified by the “,2002” version tag).

The following table declares the valid YAML type URIs and aliases that SHALL be used when defining parameters or properties within an OpenWhisk package manifest:

Type NameType URINotes,2002:str (default)Default type if no type provided,2002:intSigned. Includes large integers (i.e., long type),2002:floatSigned. Includes large floating point values (i.e., double type),2002:boolThis specification uses lowercase ‘true’ and lowercase ‘false’,2002:timestampISO 8601 compatible timestamp. See YAML-TS-1.1,2002:nullDifferent meaning than an empty string, map, list, etc.


  • The ‘string’ type SHALL be the default type when not specified on a parameter or property declaration.
  • All ‘boolean’ values SHALL be lowercased (i.e., ‘true’ or ‘false’).
  • The case (lower, upper) of the Unit’s value is considered significant and SHALL be preserved. For example, the Unit value “kB” is not the same as “KB” or “kb”.

OpenWhisk Types

In addition to the YAML built-in types, OpenWhisk supports the types listed in the table below. A complete description of each of these types is provided below.

Type NameDescriptionNotes found in modern tooling (i.e., ‘package@version’ or ‘package:version’ format). Aligns with Maven format principles, but is a simplification of Maven spec. considerations. See Maven version.
string256long length strings (e.g., descriptions)A string type limited to 256 characters.
string64medium length strings (e.g., abstracts, hover text)A string type limited to 64 characters.
string16short length strings (e.g., small form-factor list displays)A string type limited to 16 characters.
jsonThe parameter value represents a JavaScript Object Notation (JSON) data object.The deploy tool will validate the corresponding parameter value against JSON schema.Note: The implied schema for JSON the JSON Schema (see
scalar-unitConvenience type for declaring common scalars that have an associated unit. For example, “10 msec.”, “2 Gb”, etc.)Currently, the following scalar-unit subtypes are supported: scalar-unit.size, scalar-unit.time.
schemaThe parameter itself is an OpenAPI Specification v2.0 Schema Object (in YAML format) with self-defining schema.The schema declaration follows the OpenAPI v2.0 specification for Schema Objects (YAML format).
objectThe parameter itself is an object with the associated defined Parameters (schemas).Parameters of this type would include a declaration of its constituting Parameter schema.

scalar-unit types

Scalar-unit types can be used to define scalar values along with a unit from the list of recognized units (a subset of GNU units) provided below.

<scalar> <unit>

In the above grammar, the pseudo values that appear in angle brackets have the following meaning:

  • scalar: is a required scalar value (e.g., integer).
  • unit: is a required unit value. The unit value MUST be type-compatible with the scalar value.
    type: scalar-unit.size
    default: 10 GB
    type: scalar-unit.time
    default: 30 d
  • Whitespace: any number of spaces (including zero or none) SHALL be allowed between the scalar value and the unit value.
  • It SHALL be considered an error if either the scalar or unit portion is missing on a property or attribute declaration derived from any scalar-unit type.
Recognized units for sizes (i.e., scalar-unit.size)
kBkilobyte (1000 bytes)
MBmegabyte (1000000 bytes)
GBgigabyte (1000000000 bytes)
TBterabyte (1000000000000 bytes)
    type: scalar-unit.size
    value: 256 MB
Recognized units for times (i.e., scalar-unit.time)
    type: scalar-unit.time
    value: 600 s

Object type example

The Object type allows for complex objects to be declared as parameters with an optional validatable schema.

    type: object
      <Parameter schema>