Use Arrays and for-loops in BICEP - powershell

Question

I am passing an array of services into the BICEP template
param objectarray array =[]
I also have an array variable that contains a subset of the service names that I passed in
var objectarray =
[
'Abc'
'DEF'
'GHI'
]
My intention is to see if the service names being passed in are in the subset and if so, then I need to set another variable accordingly. What's the best way to do that? I've used conditional loops and if statements in BICEP before but not together.
var isInSubset =
Additional Info
I did try this
var apis_with_listener = contains(objectarray, objectarray)
but the resource that I am creating is a backend policy and i am using a for loop in the resource creation and setting the value based on what apis_with_listener is set to. Sorry, this sounds confusing.
value: '<\r\n<policies>\r\n <inbound>\r\n <base />\r\n <set-backend-service backend-id="${APIM_Name}" sf-resolve-condition="#(context.LastError?.Reason == "BackendConnectionFailure")" sf-service-instance-name="#("fabric:/${Application_Name}${Customer_AreaName}/${api}")" **sf-listener-name="${api}Service**" />\r\n </inbound>\r\n <backend>\r\n <base />\r\n </backend>\r\n <outbound>\r\n <base />\r\n </outbound>\r\n <on-error>\r\n <base />\r\n </on-error>\r\n</policies>'
so the sf-listener-name needs to be set ONLY if the service is one of the ones in the subset. Not sure how to do a for loop and an if properly
resource BackendPolicy 'Microsoft.ApiManagement/service/apis/policies#2021-04-01-preview'= [for (api,i) in API_Names : {
name: 'policy'
parent:API_Service[i]
properties: {
value: '<\r\n<policies>\r\n <inbound>\r\n <base />\r\n <set-backend-service backend-id="${APIM_Name}" sf-resolve-condition="#(context.LastError?.Reason == "BackendConnectionFailure")" sf-service-instance-name="#("fabric:/${Application_Name}${Customer_AreaName}/${api}")" sf-listener-name="${api}Service" />\r\n </inbound>\r\n <backend>\r\n <base />\r\n </backend>\r\n <outbound>\r\n <base />\r\n </outbound>\r\n <on-error>\r\n <base />\r\n </on-error>\r\n</policies>'
format: 'xml'
}
}]

Answer 1

First of all, Bicep doesn't allow loops within loops, but you don't need that here as you're just looking for whether an array contains the string value you're matching against. Let's start my saying that all the APIM policy setting is going to happen in its own module, 'sf-apimPolicy.bicep', for clarity.
You indicated that you want to pass in an array of your Service Fabric service names and see if any of them are in a subset, presumably one kept in your intended module, so we'll start with that.
// sf-apimPolicy.bicep
#description('Your APIM resource name')
param APIM_Name string
#description('The prefix of your SF application name')
param Application_Name string
#description('Used to route to the appropriate SF application per customer')
param Customer_AreaName string
#description('Contains each of your Service names being passed in')
param API_Names array //Presumably this is the 'objectarray' you mention in the question
#description('The array of service names that set a constraint on what can be set in this policy')
param ApiNameConstraints array
resource ApimService 'Microsoft.ApiManagement/service/apis#2021-04-01-preview' existing = {
name: '${APIM_Name}/${ApiServiceName}'
}
//And finally you're looking to set the policy itself if ApiNameConstraints contains your api value
resource BackendPolicy 'Microsoft.ApiManagement/service/apis/policies#2021-04-01-preview' = [for (api, i) in API_Names: if (contains(ApiNameConstraints, api)): {
name: 'policy'
parent: ApimService
properties: {
value: '''
<policies>
<inbound>
<base> // As an aside, changed this from your original value as it used a content-less close tag
<set-backend-service backend-id="${APIM_Name}" sf-resolve-condition="#(context.LastError?.Reason == "BackendConnectionFailure")" sf-service-instance-name="#("fabric:/${Application_Name}${Customer_AreaName}/${api}")" **sf-listener-name="${api}Service**" />
</base> //Also changed this as it didn't use a close tag
</inbound>
<backend>
<base />
</backend>
<outbound>
<base />
</outbound>
<on-error>
<base />
</on-error>
</policies>
'''
format: 'xml'
}
}]
Then merely call this module and populate the various parameters to call it and the loop will be handled internally.