Extracting environment variable-set config for a Backstage app.

config.yaml

#@ load("@ytt:data", "data")

#@ def removeprefix(prefix, s):
#@     return s[len(prefix):] if s.startswith(prefix) else s
#@ end

#@ def config_key_for(auth_var_expr):
#@   var_name_parts = \
#@      removeprefix("..._", auth_var_expr) \
#@      .split("_")
#@   config_key_parts = \
#@     [var_name_parts[0].lower()] + \
#@     [part.capitalize() for part in var_name_parts[1:]]
#@   return "".join(config_key_parts)
#@ end

#@ def env_var_for(provider_name, auth_var_expr):
#@   return "${AUTH_" + provider_name.upper() + "_" + removeprefix("..._", auth_var_expr) + "}"
#@ end

---
#@yaml/text-templated-strings
auth:
  #@ for provider in data.values.auth:
  (@= provider @):
    #@ for auth_var in data.values.auth[provider]:
      (@= config_key_for(auth_var) @): #@ env_var_for(provider, auth_var)
    #@ end
  #@ end

  

values.yaml

#@data/values
---
auth:
  google: ['..._CLIENT_ID', '..._CLIENT_SECRET']
  auth0: ['..._CLIENT_ID', '..._CLIENT_SECRET']