Config credentials Documentation

[MarkusGnigler]

I have a setup with only the postgres fdw and need to provide the credentials via json based config because the app/credentials-provider and the fdw run in 2 separate containers with no file exchange.

It always fails on some formatting issues. Is it possible to add some form of extended documentation of the json parsing from #318?

What is the correct hcl for json based credentials?

hcl

#with semicolons
config = """
"credentials="{...}"
"""

#without semicolons
config = """
"credentials={...}
"""

Error is:

FdwError: failed to process options: failed to parse connection config for connection 'public': Extraneous data after value: Extra characters appear after
the JSON value.
Root value must be object: The root value in a JSON-based configuration must be either a JSON object or a JSON array of objects.

json

#with semicolons
config = """{
"credentials":"{...}"
}
#without semicolons
"""
config = """{
"credentials":{...}
}
"""

Error is:

FdwError: failed to process options: failed to parse connection config for connection 'public': Missing attribute seperator comma: A comma must appear 
between each property definition in an object.
Root value must be object: The root value in a JSON-based configuration must be either a JSON object or a JSON array of objects.

How should the json object itself be formatted?

#with escape
config = """
credentials={\n\t"key":"multi\nrow"}
"""
#without escape
"""
config = """
credentials={\\n\\t"key":"multi\\nrow"}
"""