Terraform，创建可选地图列表

Question

我试图创建一个可选的iam策略，但我一直收到类型不匹配的错误，我尝试过将它包装在try中，但从来没有成功过，有人有什么想法吗？

  ssm_readonly_policies = can(coalescelist(local.ssm_parameters)) ? [
    {
      Sid    = "ReadOnlyParametersSSM"
      Effect = "Allow"
      Action = [
        "ssm:GetParameter*"
      ]
      Resource = flatten([for param in local.ssm_parameters : join(":", [
        "arn:aws:ssm", param["region"], param["account"], join("/", ["parameter", param["name"]])
      ])])
    },
    {
      Sid      = "ListOnlyParametersSSM"
      Effect   = "Allow"
      Action   = "ssm:DescribeParameters"
      Resource = "*"
    }
  ] : []

local.ssm_parameters的格式为

ssm_parameters = [
   {
     name = "blah"
     region = "blah"
     account = "blah"
   }
 ]

Answer 1

好的，我避免了if语句，在try中添加了coaleselist，所以如果它是空的，它将失败为空列表

  ssm_readonly_policies = try([
    {
      Sid    = "ReadOnlyParametersSSM"
      Effect = "Allow"
      Action = [
        "ssm:GetParameter*"
      ]
      Resource = flatten([for param in coalescelist(local.ssm_parameters) : join(":", [
        "arn:aws:ssm", param["region"], param["account"], join("/", ["parameter", param["name"]])
      ])])
    },
    {
      Sid      = "ListOnlyParametersSSM"
      Effect   = "Allow"
      Action   = "ssm:DescribeParameters"
      Resource = "*"
    }
  ], [])