Allow Concierge to start on a custom port based on the environment variable, API_PORT, passed to it:

package main 
 
import ( 
    "fmt" 
    "net/http" 
    "os" 
 
    "github.com/last-ent/distributed-go/chapter8/goophr/concierge/api" 
    "github.com/last-ent/distributed-go/chapter8/goophr/concierge/common" 
) 
 
func main() { 
    common.Log("Adding API handlers...") 
    http.HandleFunc("/api/feeder", api.FeedHandler) 
    http.HandleFunc("/api/query", api.QueryHandler) 
 
    common.Log("Starting feeder...") 
    api.StartFeederSystem() 
 
    port := fmt.Sprintf(":%s", os.Getenv("API_PORT")) 
    common.Log(fmt.Sprintf("Starting Goophr Concierge server on port %s...", port)) 
    http.ListenAndServe(port, nil) 
}