jq cannot convert string to int in bash - bash

Question

I'm working on generating a new JSON payload to update Consul with a MSSQL database service location.
When I call jq like this:
mssql_svc_ip=$(kubectl get svc/mssql-linux -o 'jsonpath={.spec.clusterIP}')
mssql_svc_port=$(kubectl get svc/mssql-linux -o 'jsonpath={.spec.ports[0].port}')
jq -n -r --arg MSSQL_IP $mssql_svc_ip --arg MSSQL_PORT $mssql_svc_port '{
"Datacenter": "dev",
"Node": "database",
"Address": $MSSQL_IP,
"Service": {
"Service": "mssql-dev",
"Port": $MSSQL_PORT
}
}'
It produces the proper structure:
{
"Datacenter": "dev",
"Node": "database",
"Address": "10.43.192.146",
"Service": {
"Service": "mssql-dev",
"Port": "1433"
}
}
I need to convert the Service.Port field from a string to an integer as that's what the Consul API requires. I can do that with tonumber, like this:
mssql_svc_ip=$(kubectl get svc/mssql-linux -o 'jsonpath={.spec.clusterIP}')
mssql_svc_port=$(kubectl get svc/mssql-linux -o 'jsonpath={.spec.ports[0].port}')
jq -n -r --arg MSSQL_IP $mssql_svc_ip --arg MSSQL_PORT $mssql_svc_port '{
"Datacenter": "dev",
"Node": "database",
"Address": $MSSQL_IP,
"Service": {
"Service": "mssql-dev",
"Port": tonumber($MSSQL_PORT)
}
}'
However, when I try and convert the $MSSQL_PORT variable to a number, I get this error:
jq: error: tonumber/1 is not defined at <top-level>, line 7:
"Port": tonumber($MSSQL_PORT)
jq: 1 compile error
At first I thought it was an assignment error and the variables weren't being passes as arguments properly, but I've tried a couple iterations and I still get the same error. What am I doing incorrectly?

Answer 1

I think you are misusing the tonumber filter. Based on the documentation it looks like the syntax would be something like:
jq -n -r --arg MSSQL_IP "$mssql_svc_ip" --arg MSSQL_PORT "$mssql_svc_port" '{
"Datacenter": "dev",
"Node": "database",
"Address": $MSSQL_IP,
"Service": {
"Service": "mssql-dev",
"Port": ($MSSQL_PORT|tonumber)
}
}'
And indeed, if $msssql_svc_ip is 10.43.192.146 and $mssql_svc_port is
1433, that gets me:
{
"Datacenter": "dev",
"Node": "database",
"Address": "10.43.192.146",
"Service": {
"Service": "mssql-dev",
"Port": 1433
}
}

Answer 2

Looks like you need to pass the number in with --argjson instead of --arg:
$ jq -n -r --argjson foo 12 '{"foo":$foo}'
{
"foo": 12
}
This seems simpler than using tonumber