Helm escape string in nested json - kubernetes-helm

Question

I am using helm to deploy apps on kubernetes. And I'm trying to figure out how to include an escaped multiline string in a nested json generated in a kubernetes secret.
The goal is to inline a certificate provided in helm chart values in nested json (for dev. purposes only)
Example values.yaml
certificate: |
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
-----BEGIN PRIVATE KEY-----
...
-----END PRIVATE KEY-----
What I tried:
configmap.yaml
apiVersion: v1
kind: Secret
stringData:
vaultfile.json: |-
[
{
"key": "myapp-config",
"value": "{\"certificate\": {{ .Values.certificate | quote | quote }} }"
}
]
Expected result:
apiVersion: v1
kind: Secret
stringData:
vaultfile.json: |-
[
{
"key": "myapp-config",
"value": "{\"certificate\": \"escaped-certificate\\ngoes\\nhere\"}"
}
]
What I got:
[
{
"key": "myapp-config",
"value": "{\"certificate\": "\"escaped-certificate\\ngoes\\nhere\"" }"
}
]
I am opened to any suggestions on how it could be done differently. But I have 2 constraints to respect:
This chart will be used as a subchart of a parent chart that won't be edited by users (making it difficult to provide certificate as a file)
Configuration format depends on an external tool and can't be modified.

Answer 1

Helm contains a toJson template function that can convert an arbitrary object to JSON. That will handle all of the string quoting and quote escaping that's necessary.
In the final structure:
The value of vaultfile.json is a JSON-encoded string.
Its value is a list.
The list contains a single object, with "key" and "value" fields.
The "value" is itself a JSON-encoded string.
That innermost string has an object, with key "certificate" and the value being the certificate.
You can build up this structure using toJson, along with dict and list to create mappings and lists. That would roughly look like:
apiVersion: v1
kind: Secret
metadata: { ... }
{{- $certObj := dict "certificate" .Values.certificate -}}
{{- $certStr := toJson $certObj -}}
{{- $kvp := "key" "myapp-config" "value" $certStr -}}
{{- $kvps := list $kvp -}}
data:
vaultfile.json: {{ $kvps | toJson | b64enc }}