{
  "properties": {
    "displayName": "Resource logs in App Services should be enabled",
    "policyType": "BuiltIn",
    "mode": "Indexed",
    "description": "Audit enabling of resource logs on the app. This enables you to recreate activity trails for investigation purposes if a security incident occurs or your network is compromised.",
    "metadata": {
      "version": "1.0.0",
      "category": "App Service"
    },
    "parameters": {
      "effect": {
        "type": "string",
        "defaultValue": "AuditIfNotExists",
        "allowedValues": ["AuditIfNotExists", "Disabled"],
        "metadata": {
          "displayName": "Effect",
          "description": "Enable or disable the execution of the policy"
        }
      },
      "requiredRetentionDays": {
        "type": "String",
        "defaultValue": "365",
        "metadata": {
          "displayName": "Required retention (days)",
          "description": "The required resource logs retention in days"
        }
      }
    },
    "policyRule": {
      "if": {
        "allOf": [
          {
            "field": "type",
            "equals": "Microsoft.Web/sites"
          },
          {
            "field": "kind",
            "notContains": "functionapp"
          }
        ]
      },
      "then": {
        "effect": "[parameters('effect')]",
        "details": {
          "type": "Microsoft.Insights/diagnosticSettings",
          "existenceCondition": {
            "count": {
              "field": "Microsoft.Insights/diagnosticSettings/logs[*]",
              "where": {
                "anyOf": [
                  {
                    "allOf": [
                      {
                        "field": "Microsoft.Insights/diagnosticSettings/logs[*].retentionPolicy.enabled",
                        "equals": "true"
                      },
                      {
                        "anyOf": [
                          {
                            "field": "Microsoft.Insights/diagnosticSettings/logs[*].retentionPolicy.days",
                            "equals": "0"
                          },
                          {
                            "field": "Microsoft.Insights/diagnosticSettings/logs[*].retentionPolicy.days",
                            "greaterOrEquals": "[parameters('requiredRetentionDays')]"
                          }
                        ]
                      },
                      {
                        "field": "Microsoft.Insights/diagnosticSettings/logs.enabled",
                        "equals": "true"
                      }
                    ]
                  },
                  {
                    "allOf": [
                      {
                        "field": "Microsoft.Insights/diagnosticSettings/logs.enabled",
                        "equals": "true"
                      },
                      {
                        "anyOf": [
                          {
                            "field": "Microsoft.Insights/diagnosticSettings/logs[*].retentionPolicy.enabled",
                            "notEquals": "true"
                          },
                          {
                            "field": "Microsoft.Insights/diagnosticSettings/storageAccountId",
                            "exists": false
                          }
                        ]
                      }
                    ]
                  }
                ]
              }
            },
            "greaterOrEquals": 1
          }
        }
      }
    }
  },
  "id": "/providers/Microsoft.Authorization/policyDefinitions/91a78b24-f231-4a8a-8da9-02c35b2b6510",
  "name": "91a78b24-f231-4a8a-8da9-02c35b2b6510"
}