Jq Replace Existing JSON with Values Complex - jq

Question

I need to generate a CloudFormation parameter list (config.json) during a CodeBuild. I have a bash script in my repo that will take a couple of parameters. This will either be production, staging, or development.
Here's the generator.json. The values here will be used to generate config.json.
{
"Parameters" : {
"FargateStackSuffix" : "environment-fargate",
"VPCStackSuffix": "environment-base-vpc",
"ContainerPort" : "80",
"ContainerCpu" : "256",
"ContainerMemory" : "512",
"Path" : "*",
"productionDesiredCount" : "3",
"stagingDesiredCount" : "2",
"developmentDesiredCount" : "1",
"ELBType" : "application",
"ELBIpAddressType": "ipv4",
"productionZone": "service.example.com",
"stagingZone": "service-staging.example.com",
"devZone": "service-dev.example.com"
}
}
For example:
./generate.sh my-service production
Would generate this:
{
"Parameters" : {
"FargateStackSuffix" : "production-fargate",
"VPCStackSuffix": "production-base-vpc",
"ServiceName" : "myservice",
"EnvironmentName" : "production",
"ContainerPort" : "80",
"ContainerCpu" : "256",
"ContainerMemory" : "512",
"Path" : "*",
"DesiredCount" : "3",
"ELBType" : "application",
"ELBIpAddressType": "ipv4",
"Zone": "myservice.example.com"
}
}
As you can see there's a bit of replacement based on additions. Just iterating over the keys won't do this. Is there a way to do all fot eh transformations I need with just jq?
EDIT: I ended up using some sed to filter replace a few values. Now I need to replace the appropriate DesiredCount:
cat .codedeploy/generator.json | jq '[paths(type == "string" and contains("DesiredCount"))]'
[]
My problem is that it's returning an empty array.

Answer 1

You can use object construction to do this.
cat generator.json | jq --arg variable $variable '{Parameters: {DesiredCount: .Parameters.developmentDesiredCount, Zone: .Parameters.devZone, environmentName: "Production", var: $variable}}'
Here I have shown a few solutions to help you.
you can reference the parameters in generator.json by using dot notation in the value for that field in the new object.
You can simply define a string
You can use the args flag to pass in a bash variable.
Output (incomplete, but shows solution)
{
"Parameters": {
"DesiredCount": "1",
"Zone": "service-dev.example.com",
"environmentName": "Production",
"var": "VariableString"
}
}

Answer 2

Here's one such way you can generate that json. Perhaps the tricky part here is generating the dynamic name for the environment DesiredCount and Zone. But jq handles that rather easily.
$ jq --arg ServiceName "myservice" --arg EnvironmentName "production" '.Parameters |=
{
FargateStackSuffix,
VPCStackSuffix,
$ServiceName,
$EnvironmentName,
ContainerPort,
ContainerCpu,
ContainerMemory,
Path,
DesiredCount: ."\($EnvironmentName)DesiredCount",
ELBType,
ELBIpAddressType,
Zone: ."\($EnvironmentName)Zone"
}
' generator.json > config.json
$ cat config.json
{
"Parameters": {
"FargateStackSuffix": "environment-fargate",
"VPCStackSuffix": "environment-base-vpc",
"ServiceName": "myservice",
"EnvironmentName": "production",
"ContainerPort": "80",
"ContainerCpu": "256",
"ContainerMemory": "512",
"Path": "*",
"DesiredCount": "3",
"ELBType": "application",
"ELBIpAddressType": "ipv4",
"Zone": "service.example.com"
}
}