Bicep and Azure Firewall Management IP Configuration

[tw3lveparsecs]

Bicep version Bicep CLI version 0.9.1

Describe the bug When using Bicep to deploy Azure firewall using a variable with a condition on the managementIpConfiguration property it fails with error The template variable 'variableName' is not found.

To Reproduce

1. Create variable with condition

   var firwallMgmtConfig = (deployMgmtConfig) ? {
   name: publicIpFirewallMgmt.name
   properties: {
   subnet: {
     id: mgmtSubnetResourceId
   }
   publicIPAddress: {
     id: publicIpFirewallMgmt.id
   }
   }
   } : null

2. Set variable on managementIpConfiguration property.

   resource firewall 'Microsoft.Network/azureFirewalls@2022-01-01' = {
   name: name
   location: location
   tags: tags
   properties: {
   sku: {
     name: sku
     tier: tier
   }
   ipConfigurations: [
     {
       name: publicIpFirewall.name
       properties: {
         subnet: {
           id: subnetResourceId
         }
         publicIPAddress: {
           id: publicIpFirewall.id
         }
       }
     }
   ]
   managementIpConfiguration: firwallMgmtConfig
   }
   }

   Additional context When moving the code from the variable directly to the property it works correctly.

   resource firewall 'Microsoft.Network/azureFirewalls@2022-01-01' = {
   name: name
   location: location
   tags: tags
   properties: {
   sku: {
     name: sku
     tier: tier
   }
   ipConfigurations: [
     {
       name: publicIpFirewall.name
       properties: {
         subnet: {
           id: subnetResourceId
         }
         publicIPAddress: {
           id: publicIpFirewall.id
         }
       }
     }
   ]
   managementIpConfiguration: (deployMgmtConfig) ? {
     name: publicIpFirewallMgmt.name
     properties: {
       subnet: {
         id: mgmtSubnetResourceId
       }
       publicIPAddress: {
         id: publicIpFirewallMgmt.id
       }
     }
   } : null
   firewallPolicy: {
     id: firewallPolicy.id
   }
   }
   }

[anthony-c-martin]

Here's a short repro - looks like the engine treats a null variable the same as a variable not being defined:

param timeNow string = utcNow()

var foo = (timeNow == 'blah') ? {
  abc: 'def'
} : null

output foo object = {
  bar: foo
}

[brwilkinson]

Thanks @anthony-c-martin I will remove myself, leave triage on, given you have the repro.

[stephaniezyen]

Can you try using nullable parameters? Here is the issue with more information on nullable parameters/variables: #6418