Nesting Resource Assistance

[Vegas588]

Hello,

Trying to figure out the child nesting syntax for subnets within a virtual network. Goal is to create separate files for vnet and subnets and eventually NSGs to use as modules. So, I want to be able to call or reference these child resource types wherever I need. I have looked at the examples and I have failed to get this working. This would be especially important in cases where we might deploy multiple vnets and subnets of different ranges. In this case, we may have a vnet1 module and a vnet 2 module and corresponding subnet1, subnet2 modules.

Thanks for your help.

//deploy virtual network
@description('The expected Azure region to deploy resources.')
param location string = resourceGroup().location
@description('The base naming for all resources.')
param namePrefix string = 'azmech'
@description('The base name of the virtual network.')
param vnetid string = 'vnet'
@description('The virtual network address space.')
param vnetAddressSpace string = '10.0.0.0/26'
@description('The tags to be used.')
param resourceTags object = {
  environment: 'dev'
  project: 'bicep_tutorial'
}

var baseName = '${namePrefix}-${location}'

resource vnet 'Microsoft.Network/VirtualNetworks@2020-07-01' = {
  name: toLower('${baseName}-${vnetid}-1')
  location: location
  tags: resourceTags
  properties: {
    addressSpace: {
      addressPrefixes: [
        vnetAddressSpace
      ]
    }
    resource subs 'subnets' = {  //Why the mismatch?
      name: //?????

    }
    }
  }
}

//deploy subnets
@description('The expected Azure region to deploy resources.')
param location string = resourceGroup().location

@description('The base naming for all resources.')
param namePrefix string = 'azmech'

@description('The base name of a virtual network subnet resource.')
param snetid string = 'snet'

var baseName = '${namePrefix}-${location}'

var subnets = [
  {
    snetPrefix: '10.0.0.0/28'
  }
  {
    snetPrefix: '10.0.0.16/28'
  }
  {
    snetPrefix: '10.0.0.32/28'
  }
  {
    snetPrefix: '10.0.0.48/28'
  }
]

resource snets 'Microsoft.Network/VirtualNetworks/subnets@2020-07-01' = [for (subnet, i) in subnets: {
  name: toLower('${baseName}-${snetid}-${i + 1}')
  properties: {
    addressPrefix: subnet.snetPrefix
  }
}]

[fluffy-cakes]

I think this should answer your question?

resource vnet1 'Microsoft.Network/virtualNetworks@2020-08-01' = {
    name: 'asdf1'
    location: 'uksouth'
    properties: {
        addressSpace: {
            addressPrefixes: [
                '1.1.1.1'
            ]
        }
    }
    resource subs1 'subnets@2020-08-01' = {
        name: 'asdf1'
        properties: {
            addressPrefix: '1.1.1.1'
        }
    }
}

or

param list array

resource vnet2 'Microsoft.Network/virtualNetworks@2020-08-01' = {
    name: 'asdf2'
    location: 'uksouth'
    properties: {
        addressSpace: {
            addressPrefixes: [
                '1.1.1.1'
            ]
        }
    }
    resource subs2 'subnets@2020-08-01' = [for item in list: {
        name: item.name
        properties: {
            addressPrefixes: [
                item.cidr
            ]
        }
    }]
}

^^ here i assumed throwing in an array of objects, which I personally prefer

[fluffy-cakes]

just to expand upon that; notice how i nested the resource OUTSIDE the properties object of the vnet. if you install VSCode Bicep extension you will get handy tips and whatnot on building out your resources.

[Vegas588]

Understood. Thanks
Now how does this work when I have 4 different files and need to reference them from outside the parent resource? From your example, it looks like the subs1 / subs2 resources are called from within the same file. Or is my understanding wrong here?

So, for example:

vnet1.bicep
vnet2.bicep
subnet1.bicep
subnet2.bicep

If they are truly separate files, how do I reference subnet1.bicep as a child of vnet1.bicep, etc.?

Thanks again!

[fluffy-cakes]

I'm not too sure what you mean by referencing subnet1 as a child of vnet1. But does this screenshot offer any help with referencing outputs and passing to another resource in another file?

You can pass a string, array or even the whole resource object out (which you could even then use dot notation to get to the sub values of that object you want).

[Vegas588]

I'll try to clarify here. If you deploy a vnet, part of that would also be deploying subnets. Subnets are a child resource of vnets, correct? NSG rules are a child of subnets, etc.

So, if a create two files - one to deploy just the vnet and one just to deploy the subnets, how would this work in Bicep?

In ARM templates, we could do this by using the templateLink option.

{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {},
  "variables": {},
  "resources": [
    {
      "type": "Microsoft.Resources/deployments",
      "apiVersion": "2020-10-01",
      "name": "linkedTemplate",
      "properties": {
        "mode": "Incremental",
        "templateLink": {
          "uri":"https://mystorageaccount.blob.core.windows.net/AzureTemplates/newStorageAccount.json",
          "contentVersion":"1.0.0.0"
        }
      }
    }
  ],
  "outputs": {
  }
}

This way, we can have separate files for the child resources.

[fluffy-cakes]

Ok, I don't think what you're trying to do in your screenshot is the same as what you've pasted in code above. Bicep is an extension of ARM, it still needs to comply with the structural design of ARM JSON. By the very nature of Bicep, a module (located in another file) will be nested within a deploymentTemplate once converted to ARM.

Using my example screenshot above; if I were to convert the Bicep file to an ARM template, it will be nested as such:

However, I do not think (note; I am not an M$ employee, so I can be wrong) that you can pass an entire resource from another file to be "nested" within it's parent type of resource. Perhaps instead, you should look at using an object to iterate over within the same network resource.

Like so:

It might also be worth check against the Azure templates to see what can be done with ARM templates, because as far as I'm aware, Bicep can only do what ARM can (but in a much easier way!)

• https://docs.microsoft.com/en-us/azure/templates/microsoft.network/virtualnetworks?tabs=json
• https://docs.microsoft.com/en-us/azure/templates/microsoft.network/virtualnetworks/subnets?tabs=json

[Vegas588]

@fluffy-cakes Ok. Will look at it. I think my initial question is related to Issue #1170