how to create a custom config file apart from config.[env].yaml

The only place you can define variables is in the config.[env].yaml file. 

I don’t think I follow here, can you describe a bit more what you mean. If you have an example that would be great.

Hello ​@Anders Albert，

We have several SQL CTE tables that need to be shared across different transformations. The most effective approach is to use placeholders within these transformations, which will then be replaced during the build phase. However, we would prefer not to define the CTE tables in the config.[env].yaml file.
 

For example: 

{{my_cmt}} is a common table that we prefer not to include in the config.[env].yaml file, but rather in a separate file that can be customized as needed.

externalId: tr-example
name: example
query: |-
  {{my_cmt}},
  SELECT
   t.space,
   t.id AS externalId,
   ...
  FROM
    table t
    JOIN cmt ON t.id= cmt.parent_id
destination:
  dataModel:
    space: {{my_space}}
    externalId: {{my_model}}
    version: "{{my_version}}"
    destinationType: 
  type: instances
ignoreNullFields: false
isPublic: true
conflictMode: upsert
dataSetExternalId: {{my_dataset}}