放置 S3 策略时出错：MalformedPolicy：策略语法无效答案

【问题标题】：Error putting S3 policy: MalformedPolicy: Invalid policy syntax放置 S3 策略时出错：MalformedPolicy：策略语法无效
【发布时间】：2021-09-02 10:08:52
【问题描述】：

我正在尝试在 Terraform 中设置 S3 存储桶策略。我在模块core/main.tf中编写了以下代码：

resource "aws_s3_bucket_policy" "access_to_bucket" {

  bucket = aws_s3_bucket.some_bucket.id

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action    = ["s3:GetObject", "s3:GetObjectAcl", "s3:ListBucket"]
        Effect    = "Allow"
        Principal = "${var.some_variable_name}"
        Resource = [
          "${aws_s3_bucket.some_bucket.arn}",
          "${aws_s3_bucket.some_bucket.arn}/*"
        ]
      },
    ]
  })
}

然后在本地模块中实例化，该模块使用 localstack 在本地运行。

这是生成的计划：

Terraform will perform the following actions:

  # module.local.aws_s3_bucket_policy.access_to_bucket will be created
  + resource "aws_s3_bucket_policy" "access_to_bucket" {
      + bucket = "some_bucket"
      + id     = (known after apply)
      + policy = jsonencode(
            {
              + Statement = [
                  + {
                      + Action    = [
                          + "s3:GetObject",
                          + "s3:GetObjectAcl",
                          + "s3:ListBucket",
                        ]
                      + Effect    = "Allow"
                      + Principal = "arn:aws:iam::000000000000:role/test_role"
                      + Resource  = [
                          + "arn:aws:s3:::some-bucket/*",
                          + "arn:aws:s3:::some-bucket",
                        ]
                    },
                ]
              + Version   = "2012-10-17"
            }
        )
    }
╷
│ Error: Error putting S3 policy: MalformedPolicy: Invalid policy syntax.
│       status code: 400, request id, host id
│ 
│   with module.local.aws_s3_bucket_policy.access_to_bucket,
│   on ../core/main.tf line 55, in resource "aws_s3_bucket_policy" "access_to_bucket":
│   55: resource "aws_s3_bucket_policy" "access_to_bucket" {
│

在本地和 AWS 中运行它最终会出现此错误。我猜这是某处的语法错误，但 AFAIK 这是正确的。有什么线索吗？

【问题讨论】：

标签： amazon-web-services amazon-s3 terraform terraform-provider-aws

【解决方案1】：

您的Principal 无效。如果您查看the Principal element 上的 IAM 用户指南（S3 存储桶策略共享相同的语法，但仅限于对存储桶的操作并组合形成最低权限访问控制），您应该会看到如下示例：

"Principal" : { 
"AWS": [ 
  "arn:aws:iam::123456789012:root",
  "arn:aws:iam::555555555555:root" 
  ]
}

这允许仅对 ID 为 123456789012 和 555555555555 的两个 AWS 账户中的用户或角色执行 IAM 操作。

在您的情况下，您希望允许 an IAM role，因此您的策略应如下所示：

{
  "Version":"2012-10-17",
  "Statement":[
    {
      "Effect": "Allow",
      "Principal": {"AWS": "arn:aws:iam::000000000000:role/test_role"},
      "Action": ["s3:GetObject", "s3:GetObjectAcl", "s3:ListBucket"],
      "Resource": ["arn:aws:s3:::some-bucket/*", "arn:aws:s3:::some-bucket"]
    }
  ]
}

Terraform 允许您自己为您的 IAM 策略编写 JSON，这可以更容易地与 Internet 上的示例进行比较，或者您可以使用 aws_iam_policy_document data source 这将为您提供更多计划时间验证，因为 Terraform 可以更好地理解你给它的结构。

与上面相同但作为aws_iam_policy_document 数据源的策略文档如下所示：

data "aws_iam_policy_document" "bucket_policy" {
  statement {
    principals {
      type        = "AWS"
      identifiers = ["arn:aws:iam::000000000000:role/test_role"]
    }

    actions = [
      "s3:GetObject",
      "s3:GetObjectAcl",
      "s3:ListBucket",
    ]

    resources = [
      "arn:aws:s3:::some-bucket",
      "arn:aws:s3:::some-bucket/*",
    ]
  }
}

resource "aws_s3_bucket_policy" "access_to_bucket" {
  bucket = aws_s3_bucket.some_bucket.id
  policy = data.aws_iam_policy_document.bucket_policy.json
}

【讨论】：