Alibaba Cloud ROS function index - Resource Orchestration Service

Resource Orchestration Service (ROS) provides various built-in functions to help you manage stacks. You can use built-in functions in the Resources and Outputs sections. This topic describes the built-in functions that are supported by ROS.

Considerations

If you use YAML to define a function in the short syntax form and specify the parameter value of the function by using another function, you must define at least one of the functions in the full syntax form. Otherwise, the functions are invalid.

Functions in the following syntax form are invalid:

!Base64Encode !Sub string
!Base64Encode !Ref logical_ID

Functions in the following syntax forms are valid:

!Base64Encode
 "Fn::Sub": string

Fn::Base64Encode:
 !Sub string

Supported functions

Function	Description
Fn::Base64Encode	Returns the Base64-encoded format of a string.
Fn::Base64Decode	Returns a string decoded from a Base64-encoded string.
Fn::Str	Returns the string form of a number.
Fn::Indent	Adjusts the indentation format of a string.
Fn::FindInMap	Returns the value that corresponds to keys in a two-level mapping declared in the Mappings section.
Fn::GetAtt	Returns the property value of a resource from a template.
Fn::Join	Combines a set of strings into a single string that is separated by a delimiter.
Fn::Sub	Substitutes variables in a string with values that you specify.
Fn::Select	Returns data elements from a list or a dictionary based on an index.
Ref	References the value of a parameter or resource.
Fn::GetAZs	Returns a list of zones that belong to a region.
Fn::Replace	Replaces a substring in a string with another substring.
Fn::Split	Splits a string into multiple values by using a delimiter.
Fn::Equals	Compares two values to check whether they are equal. If the two values are equal, true is returned. If the two values are not equal, false is returned.
Fn::And	Represents the AND operator and must contain at least two conditions. If all the specified conditions are evaluated to true, true is returned. If a condition is evaluated to false, false is returned.
Fn::Or	Represents the OR operator and must contain at least two conditions. If a condition is evaluated to true, true is returned. If all the specified conditions are evaluated to false, false is returned.
Fn::Not	Represents the NOT operator. If a condition is evaluated to false, true is returned. If a condition is evaluated to true, false is returned.
Fn::Index	Queries the index of an element in a list.
Fn::If	Returns one of two possible values. The function returns one value if a specified condition is evaluated to true, and returns the other value if not. The property values in the Resources and Outputs sections of templates support the built-in function Fn::If. You can use the pseudo parameter `ALIYUN::NoValue` as the return value to delete the property.
Fn::Length	Returns the number of elements in an object.
Fn::ListMerge	Merges multiple lists into one list.
Fn::GetJsonValue	Resolves a JSON string and queries the value of a key from the first layer.
Fn::MergeMapToList	Merges multiple mappings into a new mapping list.
Fn::Avg	Returns the average value of a set of numbers.
Fn::SelectMapList	Returns values from a list of maps.
Fn::Add	Calculates the sum of parameters.
Fn::Calculate	Returns the calculation result of an expression of the String type.
Fn::Max	Returns the largest number from a list of numbers.
Fn::Min	Returns the smallest number from a list of numbers.
Fn::GetStackOutput	Queries the output of a stack.
Fn::Jq	Supports jq features. For more information about jq features, see jq Manual (development version).
Fn::FormatTime	Returns a formatted value of the current time.
Fn::MarketplaceImage	Returns the default ID of an Alibaba Cloud Marketplace image based on the product code of the image.
Fn::Any	Checks the values in an array. If one of the values is evaluated to true, true is returned. If none of the values is evaluated to true, false is returned.
Fn::Contains	Returns true if a specified value matches at least one member in a list, and returns false if not.
Fn::EachMemberIn	Returns true if each member in a list matches at least one member in another list, and returns false if not.
Fn::MatchPattern	Checks whether a value of the String type matches the condition in a regular expression. If the value matches the condition, true is returned. Otherwise, false is returned.