AWS Cloudformation: Fn :: Register with Fn :: FindInMap?

Question

Trying to use Fn :: Join Fn :: FindInMap as shown below:

"SubnetId": {
    "Fn::FindInMap": [
        {
            "Ref": "OrganizationName"
        },
        "AZ",
        {
            "Fn::Join": [
                "",
                [
                    {
                        "Ref": "Environment"
                    },
                    {
                        "Ref": "Member1AZ"
                    }
                ]
            ]
        }
    ]
}

The elements OrganizationName, Environment, and Member1AZ are parameters. Essentially, it should connect to my comparisons and produce, for example:

"SubnetId" : { "Fn::FindInMap" : [ "Organization2", "AZ", "prod1c" ]}

However, it does not seem to output the result from Fn :: Join as the only object in Fn :: FindInMap, it correctly checks if I hardcode this section of the template.

A client error (ValidationError) occurred when calling the ValidateTemplate operation: Template error: every Fn::FindInMap object requires three parameters, the map name, map key and the attribute for return value

My mappings are as follows:

Mappings" : {
      "OrganizationDefaults" : {
            "AZ" : {
                "prod1a" : "subnet-foobar1",
                "qa1a" : "subnet-foobar2",
                "prod1c" : "subnet-foobar3",
                "qa1c" : "subnet-foobar4"
            }
      },
      "OrganizationTwo" : {
            "AZ" : {
                "prod1a" : "subnet-foobar5",
                "qa1a" : "subnet-foobar6",
                "prod1c" : "subnet-foobar7",
                "qa1c" : "subnet-foobar8"
            }
      },
},

Could someone help with this or should have done something like this before? I need to use the same template for any listed organizations, so Mappings should solve this for me if I can fix it.

Answer 1

, Fn:: Join.

Mappings" : {
      "OrganizationDefaults" : {
            "1a" : {
                "prod" : "subnet-foobar1",
                "qa" : "subnet-foobar2"
            },
            "1c"
                "prod" : "subnet-foobar3",
                "qa" : "subnet-foobar4"
            }
      },
      "OrganizationTwo" : {
            "1a" : {
                "prod" : "subnet-foobar5",
                "qa" : "subnet-foobar6"
            },
            "1c" : {
                "prod" : "subnet-foobar7",
                "qa" : "subnet-foobar8"
            }
      },
},

.

"SubnetId" : { "Fn::FindInMap" : [ { "Ref" : "OrganizationName" }, { "Ref" : "Member1AZ" }, { "Ref" : "Environment" }]}

Answer 2

@Jason, , , CloudFormation , .

, Fn::FindInMap :

• Fn::FindInMap
• Ref

Join , . , FindInMap, "3- " , :

Mappings" : {
  "OrganizationDefaults" : {
        "AZ" : {
            "prod1a" : "subnet-foobar1",
            "qa1a" : "subnet-foobar2",
            "prod1c" : "subnet-foobar3",
            "qa1c" : "subnet-foobar4"
        }
  },
  "OrganizationTwo" : {
        "AZ" : {
            "prod1a" : "subnet-foobar5",
            "qa1a" : "subnet-foobar6",
            "prod1c" : "subnet-foobar7",
            "qa1c" : "subnet-foobar8"
        }
  },
  "EnvMemberMap" : {
        "prod": {
            "1a" : "prod1a",
            "1c" : "prod1c",
        },
        "qa": {
            "1a" : "qa1a",
            "1c" : "qa1c",
        }    
  }
},

:

"SubnetId": {
    "Fn::FindInMap": [
        {
            "Ref": "OrganizationName"
        },
        "AZ",
        {
            "Fn::FindInMap": [
                "EnvMemberMap",
                {
                    "Ref": "Environment"
                },
                {
                    "Ref": "Member1AZ"
                }
            ]
        }
    ]
}