允许CloudFront使用原始访问身份访问S3存储桶

Question

我已经做了一个静态网站，托管由CloudFront服务的S3存储桶。 我想仅通过原始访问身份限制从CloudFront直接进行存储桶访问。

我尝试更新S3存储桶策略，但显示错误：

Error putting S3 policy: MalformedPolicy: Invalid principal in policy status code: 400, request id

我正在尝试使用以下政策：

resource "aws_s3_bucket_policy" "default" {
  bucket = "${aws_s3_bucket.default.id}"
  policy = <<EOF
  {
"Version": "2008-10-17",
"Statement": [
    {
        "Sid": "2",
        "Effect": "Allow",
        "Principal": {
            "AWS": "arn:aws:iam::cloudfront:user/CloudFront Origin Access Identity ${aws_cloudfront_origin_access_identity.origin_access_identity.id}"
        },
        "Action": "s3:*",
        "Resource": "arn:aws:s3:::$/*"
    }
  ]
}
EOF 
}

Answer 1

如aws_cloudfront_origin_access_identity文档中所述，最好的方法是通过使用aws_iam_policy_document数据源生成IAM策略文档，然后将其直接附加。

一个例子看起来像这样：

data "aws_iam_policy_document" "s3_policy" {
  statement {
    actions   = ["s3:GetObject"]
    resources = ["${module.names.s3_endpoint_arn_base}/*"]

    principals {
      type        = "AWS"
      identifiers = ["${aws_cloudfront_origin_access_identity.origin_access_identity.iam_arn}"]
    }
  }

  statement {
    actions   = ["s3:ListBucket"]
    resources = ["${module.names.s3_endpoint_arn_base}"]

    principals {
      type        = "AWS"
      identifiers = ["${aws_cloudfront_origin_access_identity.origin_access_identity.iam_arn}"]
    }
  }
}

resource "aws_s3_bucket" "bucket" {
  # ...
  policy = "${data.aws_iam_policy_document.s3_policy.json}"
}

如果您真的想像问题中那样手工制定IAM策略，那么您只需要以下内容：

resource "aws_s3_bucket_policy" "default" {
  bucket = "${aws_s3_bucket.default.id}"
  policy = <<EOF
{
"Version": "2008-10-17",
"Statement": [
    {
        "Sid": "2",
        "Effect": "Allow",
        "Principal": {
            "AWS": "${aws_cloudfront_origin_access_identity.origin_access_identity.id}"
        },
        "Action": "s3:*",
        "Resource": "${aws_s3_bucket.default.arn}""
    }
  ]
}
EOF 
}