CONFIGURATION_FILE.md

Configuration file

Named lists

Epiphany uses a concept called named lists in the configuration YAML. Every item in a named list has the name key to identify it and make it unique for merge operation:

...
  list:
  - name: item1
    property1: value1
    property2: value2
  - name: item2
    property1: value3
    property2: value4
...

By default, a named list in your configuration file will completely overwrite the defaults that Epiphany provides. This behaviour is on purpose so when you, for example, define a list of users for Kafka inside your configuration it completely overwrites the users defined in the Kafka defaults.

In some cases, however, you don't want to overwrite a named list. A good example would be the application configurations.

You don't want to re-define every item just to make sure Epiphany has all default items needed by the Ansible automation. That is where the _merge metadata tag comes in. It will let you define whether you want to overwrite or merge a named list by setting it to true or false.

For example you want to enable the auth-service application. Instead of defining the whole configuration/applications configuration you can do the following:

kind: configuration/applications
title: "Kubernetes Applications Config"
name: default
provider: azure
specification:
  applications:
  - _merge: true
  - name: auth-service
    enabled: true

The _merge item with true will tell epicli to merge the application list and only change the enabled: true setting inside the auth-service and take the rests of the configuration/applications configuration from the defaults.