ARM template conditional nested resources without template linking - azure

Question

I'm trying to create a conditional resource template. The devel environment is not as beefy as the production environment and I've been successful in doing this for the most part. However, I can't seem to get nested resources right.
Here's a snippet from my ARM template:
"webApp-resources": "[variables(concat('webApp-', parameters('env'), '-resources'))]",
"webApp-dev-resources": [],
"webApp-prod-resources": [
{
"name": "staging",
"type": "Microsoft.Web/sites/slots",
"location": "[resourceGroup().location]",
"apiVersion": "2015-08-01",
"dependsOn": [
"[resourceId('Microsoft.Web/sites', variables('webApp-name'))]"
]
}
],
The idea is simple, the resources variable is composed using the env parameter. The env parameter can be either dev or prod and while this works, I get the following error when I try to deploy this template.
{
"name": "[variables('webApp-name')]",
"type": "Microsoft.Web/sites",
...
"resources": "[variables('webApp-resources')]" // <- culprit!
},
The request content was invalid and could not be deserialized: 'Error converting value "[variables('webApp-resources')]" to type 'Microsoft.WindowsAzure.ResourceStack.Frontdoor.Templates.Schema.TemplateResource[]'. Path 'properties.template.resources[1].resources', line 195, position 64.'
I've also tried moving the resource into a variable and referencing the variable in a similar conditional manner, very similar to how we would do nested template linking but without the template linking.
resources: [
"[variables('webApp-resource')]" // <- this doesn't work!
]
This resulted in a similar error but different error if I recalled correctly.
From this I've concluded that ARM template syntax is not simply find and replace which I think is bad because it does make it harder to reason about what works and what doesn't. Because if it was, this would have resulted in a valid template that would work. Which I've verified by pasting the correct value into the resources section.
Has anyone had similar problems, how did you work around the issue?

Answer 1

You should be able to do this without multiple template files, but not without using nested deployments. So depending on what you're trying to avoid, try this:
{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"env": {
"type": "string",
"allowedValues": [ "dev", "prod" ]
}
},
"variables": {
"resourceArray": "[variables(concat('resources', parameters('env')))]",
"resourcesprod": [
{
"name": "as",
"type": "Microsoft.Compute/availabilitySets",
"location": "[resourceGroup().location]",
"apiVersion": "2015-06-15",
"dependsOn": [],
"properties": {
}
}
],
"resourcesdev": []
},
"resources": [
{
"name": "nest",
"type": "Microsoft.Resources/deployments",
"apiVersion": "2016-09-01",
"dependsOn": [],
"properties": {
"mode": "Incremental",
"template": {
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"resources": "[variables('resourceArray')]"
},
"parameters": {
}
}
}
],
"outputs": {}
}