Referencing JSON data in a ytt template

_ytt-loading-json.md

$ ytt --data-value-file stable_config=stable_config.json -f cluster-template-paving.yaml -f values.yml

Note: the values.yml defines the stable_config data value. Without that declaration, the implied overlay from --data-value-file would fail. That is: values provided on the command-line overlay values from data value files.

cluster-template-paving.yaml

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

#@ stable_config = json.decode(data.values.stable_config)
vpc_id: #@ stable_config["vpc_id"]
second_subnet_id: #@ stable_config["pks_subnet_ids"][1]

stable_config.json

{
  "vpc_id": "pete",
  "pks_subnet_ids": [ 1, 2, 3 ]
}

values.yml

#@data/values
---
stable_config: ~