How to return Redis primaryKey via ARM template output?

Question

I am trying to deploy Redis with the help of the ARM template listed below - and then return its primary key (the secret string available in Azure portal for Redis under "Access keys" -> "Primary"):

However I get the error message from my pipeline "AzureResourceManagerTemplateDeployment@3" task:

[error]Unable to evaluate template outputs: 'RedisCachePassword'. Please see error details and deployment operations. Please see https://aka.ms/arm-debug for usage details.

[error]Details:

[error]DeploymentOutputEvaluationFailed: The template output 'RedisCachePassword' is not valid: The language expression property 'primaryKey' can't be evaluated..

What is please wrong with my ARM template below? And how to be able to find the correct names in such cases?

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "redisCacheName": {
            "defaultValue": "my-redis",
            "type": "String"
        }
    },
    "variables": {
        "resourceName": "[concat(resourceGroup().name, '-', parameters('redisCacheName'))]"
    },
    "outputs": {
      "RedisCacheEndpoint": {
        "type": "string",
        "value": "[concat(reference(variables('resourceName')).hostName, ':', reference(variables('resourceName')).sslPort)]"
      },
      "RedisCachePassword": {
        "type": "string",
        "value": "[reference(variables('resourceName')).accessKeys.primaryKey]"
      }
    },
    "resources": [
        {
            "type": "Microsoft.Cache/Redis",
            "apiVersion": "2019-07-01",
            "name": "[variables('resourceName')]",
            "location": "[resourceGroup().location]",
            "properties": {
                "sku": {
                    "name": "Basic",
                    "family": "C",
                    "capacity": 1
                },
                "enableNonSslPort": false
            }
        }
    ]
}

Why does not [reference(variables('resourceName')).accessKeys.primaryKey] work?

Alex AIT Alex AIT · Accepted Answer · 2020-05-07T21:46:59

Be aware that those outputs are in some ways quite visible. You might be better off invoking the listKeys command outside of your outputs. You can use it in other templates or execute the command separately via AzureCLI or Powershell.

If you know what you are doing, this is how you should be able to set it up:

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "redisCacheName": {
            "defaultValue": "myredisinstance",
            "type": "String"
        }
    },
    "variables": {
        "resourceId": "[resourceId('Microsoft.Cache/Redis', parameters('redisCacheName'))]",
        "apiVersion": "[providers('Microsoft.Cache', 'redis').apiVersions[0]]"
    },
    "outputs": {
      "RedisCachePassword": {
        "type": "string",
        "value": "[listKeys(variables('resourceId'), variables('apiVersion')).primaryKey]"
      }
    },
    "resources": []
}

Here is some more information about how this works in general.

To "debug" such things, I like to use https://resources.azure.com, and look at the output and the "actions" tab:

How to return Redis primaryKey via ARM template output?

2 Answers