似乎 ARM 模板中的所有表达式都是预先计算的，因此即使资源的条件为 false，也会计算该资源中的表达式。
无论条件是否显式设置为 false 或者是否是计算结果为 false 的表达式，情况似乎都是如此。
这种行为在案例资源迭代中是有问题的，因为资源中的表达式可能引用参数或变量的 copyIndex()。但是，变量的参数是一个空数组，这些表达式的计算将失败，并显示类似于以下内容的消息 -
The language expression property array index '0' is out of bounds.. Please see https://aka.ms/arm-template-expressions for usage details.
有什么方法可以修改我的模板，使其无论是否有任何资源需要添加都可以正常工作吗？
示例模板
请注意，我已经必须“破解”copy 对象的 count 参数。如果它是 0(因为表达式 length(variables('productsJArray')) 可能计算为)，模板验证将失败并出现以下错误 -
The copy count must be a postive integer value and cannot exceed '800'.
我认为，如果 count 为 0，则不会添加任何资源，这是一个合理的期望 - 但这是一个完全不同的主题!
{
"$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"apiManagementServiceName": {
"type": "string",
"metadata": {
"description": "The name of the API Management instance."
}
},
"productsJson": {
"type": "string",
"metadata": {
"description": "A JSON representation of the Products to add."
}
}
},
"variables": {
"productsJArray": "[json(parameters('productsJson'))]"
},
"resources": [
{
"condition": "[greater(length(variables('productsJArray')), 0)]",
"type": "Microsoft.ApiManagement/service/products",
"name": "[concat(parameters('apiManagementServiceName'), '/', variables('productsJArray')[copyIndex()].name)]",
"apiVersion": "2018-06-01-preview",
"properties": {
"displayName": "[variables('productsJArray')[copyIndex()].displayName]",
"description": "[variables('productsJArray')[copyIndex()].description]",
"state": "[variables('productsJArray')[copyIndex()].state]",
"subscriptionRequired": "[variables('productsJArray')[copyIndex()].subscriptionRequired]",
"approvalRequired": "[variables('productsJArray')[copyIndex()].approvalRequired]"
},
"copy": {
"name": "productscopy",
"count": "[if(greater(length(variables('productsJArray')), 0), length(variables('productsJArray')), 1)]"
}
}
]
}
可用的示例参数文件
请注意，虽然这看起来不错，但在某些情况下，productsJson 参数值可能是任何空数组 []，这就是我的问题所在出现了。
{
"$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"apiManagementServiceName": {
"value": "my-api-management"
},
"productsJson": {
"value": "[{\"name\":\"my-product\",\"displayName\":\"My Product\",\"description\":\"My product is awesome.\",\"state\":\"published\",\"subscriptionRequired\":true,\"approvalRequired\":false}]"
}
}
}
将失败的示例参数文件
{
"$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"apiManagementServiceName": {
"value": "lmk-bvt-conveyorbot"
},
"productsJson": {
"value": "[]"
}
}
}
更新了模板
源自用户“4c74356b41”的建议之一。
此模板生成以下错误 -
Unable to process template language expressions for resource '/subscriptions/**********/resourceGroups/**********/providers/Microsoft.Resources/deployments/api-management-products' at line '1' and column '839'. 'The template function 'copyIndex' is not expected at this location. The function can only be used in a resource with copy specified.
{
"$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"apiManagementServiceName": {
"type": "string",
"metadata": {
"description": "The name of the API Management instance."
}
},
"productsJson": {
"type": "string",
"metadata": {
"description": "A JSON representation of the Products to add."
}
}
},
"variables": {
"productsJArray": "[json(parameters('productsJson'))]"
},
"resources": [
{
"condition": "[greater(length(variables('productsJArray')), 0)]",
"type": "Microsoft.Resources/deployments",
"name": "api-management-products",
"apiVersion": "2017-05-10",
"properties": {
"mode": "Incremental",
"template": {
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"resources": [
{
"type": "Microsoft.ApiManagement/service/products",
"name": "[concat(parameters('apiManagementServiceName'), '/', variables('productsJArray')[copyIndex('productscopy')].name)]",
"apiVersion": "2018-06-01-preview",
"properties": {
"displayName": "[variables('productsJArray')[copyIndex('productscopy')].displayName]",
"description": "[variables('productsJArray')[copyIndex('productscopy')].description]",
"state": "[variables('productsJArray')[copyIndex('productscopy')].state]",
"subscriptionRequired": "[variables('productsJArray')[copyIndex('productscopy')].subscriptionRequired]",
"approvalRequired": "[variables('productsJArray')[copyIndex('productscopy')].approvalRequired]"
},
"copy": {
"name": "productscopy",
"count": "[if(greater(length(variables('productsJArray')), 0), length(variables('productsJArray')), 1)]"
}
}
]
}
}
}
]
}
最佳答案
有两种方法可以解决这个问题:
if()hack，所以如果length == 0，length = 1。使用这种方法，您需要有一个要引用的代理对象，因为引用不存在的对象是行不通的。- 使用嵌套部署，您可以在部署上设置一个条件，以便在
length == 0时部署不会启动(并且您在嵌套部署内运行循环)。这样你就不必关心零的长度。
关于azure - ARM 资源迭代因空数组而失败，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53722613/