- 14 Aug 2023
- 2 Minutes to read
- Updated on 14 Aug 2023
- 2 Minutes to read
Variables allow for extreme flexibility when modeling your infrastructure and creating Plans. There are many uses for variables, some of the most common are:
- Arguments/properties of Operations
- Conditional execution using an If/Else Block
- Iteration/enumeration using a Loop Block
Runtime Variable Types
There are three types of runtime variables, and each is denoted by a prefix:
|$||String||a single value|
|@||List||an enumerable set of either Lists or Strings|
|%||Map||a set of key/value pairs with values being a String, List, or Map|
String variables are the most common, and are used just about anywhere. Whenever you reference a string variable within another block or statement, it is automatically replaced with the value. You can escape this with the grave apostrophe (
Text Editor (OtterScript)
List variables are used much less frequently, primarily as the source of a Loop Block.
Map variables are pretty rare, and are only used in operations needing an arbitrary list of key/value pairs (like the
HTTP::Post) or in other really advanced scenarios.
Runtime Variable Scoping
When you create a runtime variable with the Set Variable Value statement, that variable will be accessible in the current and nested blocks. For example:
Text Mode (OtterScript)
While setting both runtime and Configuration Variables may lead to confusion if overused, Otter does allow for greater reuse of plans and templates by allowing the same plan or template to be used at different development environments where things like certificates, keys, and data might need to be different for testing.
Relation to Configuration Variables
When a string variable is referenced in your plan, the execution engine first checks to see if a runtime variable with that name exists in the current scope. If not, a configuration variable with that name is retrieved. We generally do not recommend doing this, as it can get quite confusing when others try to understand your plan.
You may have seen expressions like
$PathCombine($RootPath,Accounts) used in previous examples; these are variable functions, which take in a number of parameters and return a value.
All of the "built-in variables" like
@AllServers are implemented as variable functions.
You can create configuration or runtime variables with the same name of a variable function, but we do not recommend this because it can get quite confusing when others try to understand your plan. If there is a variable with the same name, that value will be used instead unless you explicitly reference the parameter list (such as
Variable functions are extensible, so you can write your own with an Otter Extension.