Generate fields using environment variables and insert them into object - json

Question

I have below JSON where in I need to add key and values at a specific place from env variable. Moreover would try to avoid any hardcoding in JSON if possible
Sample JSON:
{
"abc": {
"admin": {
"username": "admin",
"password": "pa55word",
"tenant_name": "t1"
},
"users": [
{
"username": "n1",
"password": "password",
"user_domain_name": "Default",
"project_name": "p1",
"project_domain_name": "Default"
},
{
"username": "n2",
"password": "password",
"user_domain_name": "Default",
"project_name": "p2",
"project_domain_name": "Default"
}
]
}
}
Output json needs to be like below where in $AUTH and $REG are env variables.
{
"abc": {
"auth_url": "$AUTH",
"region_name": "$REG",
"endpoint_type": "PRIVATE",
"admin": {
"username": "admin",
"password": "pa55word",
"tenant_name": "t1"
},
"users": [
{
"username": "n1",
"password": "password",
"user_domain_name": "Default",
"project_name": "p1",
"project_domain_name": "Default"
},
{
"username": "n2",
"password": "password",
"user_domain_name": "Default",
"project_name": "p2",
"project_domain_name": "Default"
}
]
}
}
Looked into jq but it seemed confusing. How this can be achieved using jq?

Answer 1

Grab AUTH and REG environment variables from $ENV preset variable and create fields using them, then add the resulting object to the first member of the input. E.g:
first(.[]) |= ( $ENV | {
auth_url: .AUTH,
region_name: .REG,
endpoint_type: "PRIVATE"
}
) + .

Answer 2

The simplest approach would be to take advantage of the fact that + on objects respects the ordering of keys:
.abc |= {auth_url: env.AUTH, region_name: env.REG, endpoint_type: "PRIVATE"} + .
This assumes that AUTH and REG are environment variables. If they are not, then you could use the --arg and/or --argjson command-line options, e.g.
jq --arg AUTH "$AUTH" --arg REG "$REG" '
.abc |= {auth_url: $AUTH, region_name: $REG, endpoint_type: "PRIVATE"} + .
' sample.json