How do you convert from camel case to snake case in Terraform? How do you go from "MyProjectName" to "my-project-name"? Here is a simple solution:
locals {
# convert to snake case
snake_case_name = lower(replace(var.camel_case_name,
"/(\\w)([A-Z])/", "$${1}_$2"))
}
Basically, you add an underscore before each capital letters. The strange syntax with the double dollars is a workaround to a strange bug in Terraform, which considers '$1_' as meaning something.
This line works well if you have simple cases like "MyDatabaseName". However, I had to handle some more complex cases, like "ABCProject", or "ProjectABC". In that case, you have to work a bit more.
My solution was to implement two replace functions:
- One for a series of capital letters anywhere in my word. I insert an underscore only if my capital letter is followed by a lower case.
- One for a series of capital letters at the end of my word. I insert an underscore before the first letter of the series.
This gives this more complex command:
locals {
# convert to snake case
snake_case_name = lower(replace(replace(var.camel_case_name,
# add underscore before capital letter followed by lowcase
"/(\\w)([A-Z][a-z])/", "$${1}_$2"),
# add underscore before capital letters at the end of the word
"/([A-Z]+)$/", "_$1"))
}
