Terraform，创建可选的地图列表

Question

我试图创建一个可选的iam策略，但我一直得到类型不匹配的错误，我试过包装它在尝试的，但它从来没有成功过，有人有任何想法吗?

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的格式。ssm_parameters是

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

Answer 1

我通过在try中添加coaleselist来避免if语句来解决这个问题所以如果它为空，它将无法创建空列表

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 = "*"
}
], [])