Ubuntu – How to convert Jenkins string parameter to Terraform map variable?

I’m trying to pass string parameter(s) to a Terraform map variable, but receiving error "Invalid number literal". It’s not quite clear how to access keys and values in Terraform maps when passing a Jenkins parameter via terraform apply -var ...

Jenkinsfile:

pipeline {
    agent any

    parameters {
        string(name: 'IP1', defaultValue: '', description: 'Enter first IP address')
    }
    
    stages {
        stage('Git Checkout') {
            steps {
                git branch: 'branch1', credentialsId: '', url: 'http://<redacted>.git'
            }
        }
        stage('Deploy Terraform') {
            steps {
                script {
                        dir('Linux') {
                                sh """
                                terraform init
                                terraform plan
                                terraform apply -var 'vms=${params.IP1}' 
                                --auto-approve
                                """
                            }
                    } 
                }
            }
        }
    }
}

variables.tf

variable "vm_map" {
  type = map(object({
    name = string
    ip   = string
  }))
  default = {
    "first" = {
      name = "ubuntu-jenkins1"
      ip   = "172.30.100.160"
    }
    "second" = {
      name = "ubuntu-jenkins2"
      ip   = "172.30.100.161"
    }
    "third" = {
      name = "ubuntu-jenkins3"
      ip   = "172.30.100.162"
    }
  }
}