Using information from existing resources - requires a value that can be calculated at the start of the deployment

[ehrnst]

Bicep version
Bicep CLI version 0.4.451

Describe the bug
I'm trying to provision a public ip from an existing prefix. And I want to use information about sku and zones from that prefix. However these values cannot be evaluated, and hence i get an error in bicep. I have tried to set dependsOn without any effect.

To Reproduce

resource pipPrefix 'Microsoft.Network/publicIPPrefixes@2021-02-01' existing = {
  name: '${env}-pip-prefix'
  scope: resourceGroup('test-${env}-rg')
}

resource aksEgressIp 'Microsoft.Network/publicIPAddresses@2021-02-01' = {
  name: '${aksSettings.clusterName}-egress-pip'
  location: resourceGroup().location
  sku: {
    name: 'Standard'
    tier: 'Regional'
  }
  zones: pipPrefix.zones
  properties:{
    publicIPAllocationMethod: 'Static'
    publicIPPrefix: {
      id: pipPrefix.id
    }
  }
}

[alex-frankel]

Unfortunately we have a runtime limitation that requires any top level properties (name, zones, etc.) to be known at "compile-time" and so it can't be a runtime reference to an existing resource. My understanding is that this only needs to be restricted for name since we need to construct the resource ID with that name. For the others like sku and zones we should be able to relax the restriction.

In the meantime, you may be able to work around this with modules. If you pass in pipPrefix.zones as a param to a module which creates the publicIPAddress, I think you avoid the check.

[ehrnst]

Unfortunately we have a runtime limitation that requires any top level properties (name, zones, etc.) to be known at "compile-time" and so it can't be a runtime reference to an existing resource. My understanding is that this only needs to be restricted for name since we need to construct the resource ID with that name. For the others like sku and zones we should be able to relax the restriction.

In the meantime, you may be able to work around this with modules. If you pass in pipPrefix.zones as a param to a module which creates the publicIPAddress, I think you avoid the check.

Thanks, i will try that!

[ghost]

Hi ehrnst, this issue has been marked as stale because it was labeled as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. Thanks for contributing to bicep! 😄 🦾