Using an environment variable as a map for common tags in a locals block

Hello all,
I’ve run into a specific problem while trying to automate a tagging process in terraform. I’ve set an environment variable that is essentially a list of all the tags we’d be using for all resources provisioned in the apply. It looks like this…

export TF_VAR_taglist='{JiraEpic = "ETOS-56","AssignedResearcherPri" = "Isaac",AssignedResearcherSec = "Matt"}'

After setting the environment variable I added a variable called “taglist” in the file that grabs the aforementioned environment variable. It looks like this…

variable "taglist"{}

Lastly, I have another file where i set a common_tags variable. Like so…

locals { common_tags ="${var.taglist}" }

When i terraform apply, the build fails while trying to map the tags properly. This is the error i receive…

Error: Incorrect attribute value type

  on line 9, in resource "aws_instance" "master":
   9:   tags = local.common_tags
    | local.common_tags is "{JiraEpic = \"ETOS-56\",AssignedResearcherPri = \"Isaac \",AssignedResearcherSec = \"Matt\"}"

Inappropriate value for attribute "tags": map of string required.

I then decided to define the type of the variable as map(string in the file like this
variable "taglist"{ type = map(string) }
I had hoped that this would allow terraform to recognize this variable as a map of strings and not just a string literal, but I was wrong, and these are the errors I get when that definition is applied.

Error: Missing attribute separator

  on <value for var.taglist> line 1:
  (source code not available)

Expected a newline or comma to mark the beginning of the next attribute.

Error: No value for required variable

  on line 11:
  11: variable "taglist"{

The root module input variable "taglist" is not set, and has no default value.
Use a -var or -var-file command line argument to provide a value for this

I’m really stuck on this, and I feel like I’m close. Can anyone provide some insight into this and how I should go about solving it?