Cloudformation complains "array items are not unique"-CodePudding

The cloudformation template is valid, but giving an error which seems to be undocumented.

Properties validation failed for resource MoodleRDS with message: #/VPCSecurityGroups: array items are not unique

Code is uploaded at github because it was too long for the post.

https://github.com/rkhyd/MoodleQuickStart/blob/main/MoodleQuickStartv2.json

Any ideas on how to fix?

I checked in the documentation, but could not find any such reference.

Thanks in advance

CodePudding user response：

The issue is actually pretty clear. It says that you have values in your security groups list that are not unique. Here's what you put :

"VPCSecurityGroups": [
                {
                    "Fn::GetAtt": [
                        "DBSecGroup",
                        "GroupId"
                    ]
                },
                {
                    "Ref": "DBSecGroup"
                }
            ],

What you did here is, you put 2 values in your list, but they are actually the same value... Fn:GetAtt will give you the DBSecGroup id, and the same will happen with "Ref":"DBSecGroup" which means that effectively, you put 2 values that are exactly the same in the list. Remove one of those and it will be ok.