App not connecting to database

Nomad
1

I tried to connect my app to the database PostgreSQL but it failed always . The app is developed using golang.
— postgres job–
variable “datacenters” {
description = “A list of datacenters in the region which are eligible for task placement.”
type = list(string)
default = [“dc1”]
}

variable “region” {
description = “The region where the job should be placed.”
type = string
default = “global”
}
variable “postgres_db” {
description = “Postgres DB name”
default = “vehicle_master_bd”
}

variable “postgres_user” {
description = “Postgres DB User”
default = “postgres”
}

variable “postgres_password” {
description = “Postgres DB Password”
default = “postgres”
}

job “databases” {
region = var.region
datacenters = var.datacenters
type = “service”
group “database” {
count = 1
network {
port “db” {
to = 5432
}
}
service {
name = “postgres-service”
port = “db”
provider=“nomad”
}

task "postgres" {
  driver = "docker"
  config {
    image = "postgres"
    ports = ["db"]
  }
  resources {
    cpu    = 500
    memory = 500
  }
  env {
   
    POSTGRES_DB       = var.postgres_db
    POSTGRES_USER     = var.postgres_user
    POSTGRES_PASSWORD = var.postgres_password
  }
}

}
}
— app job—
variable “datacenters” {
description = “A list of datacenters in the region which are eligible for task placement.”
type = list(string)
default = [“dc1”]
}

variable “region” {
description = “The region where the job should be placed.”
type = string
default = “global”
}
variable “postgres_db” {
description = “Postgres DB name”
default = “vehicle_master_bd”
}

variable “postgres_user” {
description = “Postgres DB User”
default = “postgres”
}

variable “postgres_password” {
description = “Postgres DB Password”
default = “postgres”
}
job “vehicleMaster” {
datacenters = var.datacenters
region = var.region
type = “service”
group “vehicleMaster” {
count = 1
network {
port “api” {
to = 50080
}
}
service {
name = “vehicleMaster-api”
tags = [“vehicleMaster”, “RESTAPI”]
port = “api”
provider = “nomad”
}
restart {
attempts = 2
interval = “30m”
delay = “15s”
mode = “fail”
}

task "vehicleMaster-container" {
  driver = "docker"

template {
data = <<EOH
{{ range nomadService “postgres-service” }}
DB_CONN=“host={{ .Address }} port={{ .Port }} user={var.postgres_user} password={var.postgres_password} dbname={var.postgres_db} sslmode=disable" {{ end }} EOH destination = "local/env.txt" env = true } env { DB_CONN = "host={NOMAD_IP_postgres-service} port={NOMAD_PORT_db} user={var.postgres_user} password={var.postgres_password} dbname={var.postgres_db} sslmode=disable”
PORT = “50080”
}
config {
image = “jpalaparthi/vehiclemaster:v0.0.3”
ports = [“api”]
}
resources {
cpu = 500 # 500 MHz
memory = 512 # 256MB
}
}
}
}