Encoding a string value with proper indenting.

template.yaml

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

#@ def config():
#@yaml/text-templated-strings
config:
  inputs: |-
    (@ for app, ns in data.values.logging.apps: -@)
    [INPUT]
      app: (@= app @)
      ns: (@= ns @)
    (@ end @)
#@ end

---
spec:
  source:
    helm:
      values: #@ yaml.encode(config())

values.yaml

#@data/values
---
logging:
  apps: [[app1, ns1], [app2, ns2]]