How do I use dependsOn on a copyIndex (array) resource? - azure

Question

I'm using an arm template to deploy topics and subscriptions. My resources to be deployed are of type Microsoft.Resources/deployments because I'm targeting a resource group external to where the deployment lives.
If the topics already exists, the template works.
Because arm template resources are deploy in parallel, I need to have the topics deploy before the subscriptions - this ordering is made possible by dependsOn.
The problem I'm having is that because the "name" value of the topics have a copyIndex(), I'm not sure how I can target the topic resource.
Among the many things I have tried, here are some:
[concat(parameters('serviceBusNamespaceName'), '/', parameters('subscriptions')[copyIndex()].topic)]
[resourceId('Microsoft.Resources/deployments',
parameters('topics'))]
["topicLoop"]
Here are the topics and subscriptions resource objects in my template:
{
"apiVersion": "2018-02-01",
"type": "Microsoft.Resources/deployments",
"name": "[concat(parameters('serviceBusNamespaceName'), copyIndex())]",
"resourceGroup": "[parameters('sharedResourcesResourceGroupName')]",
"copy": {
"name": "topicLoop",
"count": "[length(parameters('topics'))]"
},
"properties": {
"mode": "Incremental",
"template": {
"$schema": "2018-05-01",
"contentVersion": "1.0.0.0",
"resources": [
{
"type": "Microsoft.ServiceBus/namespaces/topics",
"name": "[concat(parameters('serviceBusNamespaceName'), '/', parameters('topics')[copyIndex()])]",
"apiVersion": "2017-04-01",
"location": "[resourceGroup().location]",
"properties": {}
}
]
}
}
},
{
"apiVersion": "2018-02-01",
"type": "Microsoft.Resources/deployments",
"name": "[concat(parameters('subscriptions')[copyIndex()].topic, copyIndex())]",
"resourceGroup": "[parameters('sharedResourcesResourceGroupName')]",
"copy": {
"name": "subscriptionLoop",
"count": "[length(parameters('subscriptions'))]"
},
"properties": {
"mode": "Incremental",
"template": {
"$schema": "2018-05-01",
"contentVersion": "1.0.0.0",
"resources": [
{
"type": "Microsoft.ServiceBus/namespaces/topics/subscriptions",
"name": "[concat(parameters('serviceBusNamespaceName'), '/', parameters('subscriptions')[copyIndex()].topic, '/', parameters('subscriptions')[copyIndex()].subscription)]",
"apiVersion": "2017-04-01",
"location": "[resourceGroup().location]",
"properties": {}
}
]
}
},
"dependsOn": [
// what goes here?! I need to have this depend on the topics
]
}

Answer 1

The dependsOn value is simply:
"dependsOn" : ["topicLoop"]
But it needed to be on the most external resource and not nested template.

Answer 2

yes, you can use dependsOn for each individual resource if you can generate its name. or you can hardcode those. either way, you can dependsOn the whole loop by using its name or individual resources inside the loop by referencing them by their name