Is it possible to read JSON from a file in ARM templates? - azure

Question

Lets say I want to deploy a Logic App using an ARM template. Here is a part of my azuredeploy.json:
...
parameters: {
"logic-app-definition": {
"type": "string",
"metadata": {
"description": "The JSON definition of the logic app."
}
}
},
resources: [
{
"apiVersion": "2016-06-01",
"name": "lapp-my-sample",
"type": "Microsoft.Logic/workflows",
"location": "[resourceGroup().location]",
"properties": {
"definition": "[json(parameters('logic-app-definition'))]",
"state": "Enabled"
}
]
As you can see, the actual JSON definition of the Logic App will be taken from a string-paraemter. This is pretty uncomfortable because the template-JSON is mostly a one-line-JSON-mess mostly.
I wonder if there is a function to read the string-value from a file instead.

Answer 1

There's no way to readFromUri() or anything that direct but you don't need to keep your source in a string or single-line JSON file. Depends a bit on your orchestration (e.g. how you deploy) you can do some manipulation there and pass in a parameter or pull from a "config store" (appConfigStore, keyVault).
Happy to explore some options if you want to...

Answer 2

After #bmoore-msft's answer I decided to share my imprefect solution with the community.
First a simplified version of my deploy.ps1 for brevity:
# the initial stuff like parameters and connectivity etc.
# read file content and perform regex
$ParameterFileContent = Get-Content $TemplateParametersFile
$fileName = [regex]::Matches($ParameterFileContent, "getFileJson\('(.*?)'").captures.groups[1].value
$jsonContent = (Get-Content $fileName -Raw).Replace("`n","").Replace(" ", "")
$jsonContent = [regex]::Matches($jsonContent, '{"definition":(.*)}{1}$').captures.groups[1].value
$jsonContent = $jsonContent.Replace('"', '\"')
$result = [regex]::Replace($ParameterFileContent, "[\[]getFileJson\('(.*?)'\)[\]]", $jsonContent)
Set-Content $TemplateParametersFile -Value $result
# perform deployment
New-AzResourceGroupDeployment -Name ((Get-ChildItem $TemplateFile).BaseName + '-' + ((Get-Date).ToUniversalTime()).ToString('MMdd-HHmm')) `
-ResourceGroupName $ResourceGroupName `
-TemplateFile $TemplateFile `
-TemplateParameterFile $TemplateParametersFile `
-Force -Verbose `
# reset the template file to the original version
Set-Content $TemplateParametersFile -Value $ParameterFileContent
here then is my template parameter file:
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentParameters.json#",
"contentVersion": "1.0.0.0",
"parameters": {
...
"logic-app-definition": {
"value": "[getFileJson('logicApp.json')]"
}
}
}
And finally here is my json template file for the logic app (logicapp.json):
{
"definition": {
"$schema": "https://schema.management.azure.com/providers/Microsoft.Logic/schemas/2016-06-01/workflowdefinition.json#",
"actions": {
"Condition": {
"actions": {},
"expression": {
"and": [
{ "equals": ["#outputs('HTTP')['statusCode']", 200] }
]
},
"runAfter": { "HTTP": ["Succeeded"] },
"type": "If"
},
"HTTP": {
"inputs": {
"headers": { "Accept": "application/json" },
"method": "POST",
"uri": "https://myuri/"
},
"runAfter": {},
"type": "Http"
}
},
"contentVersion": "1.0.0.0",
"outputs": {},
"parameters": {},
"triggers": {
"Recurrence": {
"recurrence": { "frequency": "Hour", "interval": 6 },
"type": "Recurrence"
}
}
},
"parameters": {}
}
So I basically create a new magic "function" getFileJson and then I use RegEx before I deploy this thing.

Answer 3

It sounds like what you are trying to do can be done using linked templates:
https://learn.microsoft.com/en-us/azure/azure-resource-manager/templates/linked-templates#linked-template
This way you can keep the Logic App template in a separate file. You can still use parameters to deploy.