Interpolatation Template

mlp is supporting a templating engine that is used in some of the commands to been able to use environment values as sources of part of the manifests generated by Mia-Platform Console.

For now the templating engine is only supporting the substitution of values contained in environment variables using their direct name encompassed between {{}} without spaces. Like for example:

apiVersion: v1
kind: Secret
metadata:
  name: example
type: Opaque
data:
  key: {{ENVIRONMENT_NAME}}

The commands that support the interpolation template will also support to set a series of prefixes to prepend to the environment variable name to allow overrides and default values. The rule is that every prefixes will be check in order before the actual variables and if a value is found the call chain is stopped.
For example if you set two prefixes like TEST_ and PRODUCTION_ for the previous yaml, the interpolation engine will check the existence of TEST_ENVIRONMENT_NAME, PRODUCTION_ENVIRONMENT_NAME and ENVIRONMENT_NAME in order and substitute the first of this three variables that contains a value.

By default this interpolation will set the value on a single line putting the \n character explicitly for every new line found in the value.
If the interpolation sequence is found surrounded by the " or ' character we will also escape the content contained in the environment for you so that the resulting string will be a valid double or single quoted string.