MalformedPolicyDocument error when creating policy via terraform

Question

I am getting the following error when running terraform:

* aws_iam_role_policy.rds_policy: Error putting IAM role policy my-rds-policy: MalformedPolicyDocument: The policy failed legacy parsing

Here is my definition of the resource:

resource "aws_iam_role_policy" "rds_policy" {
  name = "my-rds-policy"
  role = "${aws_iam_role.rds_role.id}"
  policy = <<EOF
  {
  "Version": "2012-10-17",
  "Statement": [
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetBucketLocation"
          ],
          "Resource": [
              "arn:aws:s3:::my-bucket"
          ]
      },
      {
          "Effect": "Allow",
          "Action": [
              "s3:GetObjectMetaData",
              "s3:GetObject",
              "s3:PutObject",
              "s3:ListMultipartUploadParts",
              "s3:AbortMultipartUpload"
          ],
          "Resource": [
              "arn:aws:s3:::my-bucket/backups/*"
          ]
      }
  ]
}
EOF
}

The JSON policy doc is well formed, and I can't see anything obvious.

Answer 1

You need to make sure that you don't have any indentation at the start of your EOF heredoc because your JSON policy should not start with an indented brace.

So you should be fine with this small change:

resource "aws_iam_role_policy" "rds_policy" {
  name = "my-rds-policy"
  role = "${aws_iam_role.rds_role.id}"
  policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
      {
          "Effect": "Allow",
          "Action": [
              "s3:ListBucket",
              "s3:GetBucketLocation"
          ],
          "Resource": [
              "arn:aws:s3:::my-bucket"
          ]
      },
      {
          "Effect": "Allow",
          "Action": [
              "s3:GetObjectMetaData",
              "s3:GetObject",
              "s3:PutObject",
              "s3:ListMultipartUploadParts",
              "s3:AbortMultipartUpload"
          ],
          "Resource": [
              "arn:aws:s3:::my-bucket/backups/*"
          ]
      }
  ]
}
EOF
}