app.go

package main

import "fmt"
import "net/http"
import "os"
import "github.com/go-chi/chi"
import "github.com/jmoiron/sqlx"

import _ "github.com/go-sql-driver/mysql"

func main() {
    mapper := func(name string) string {
        value := os.Getenv(name)
        switch name {
        case "DB_HOST":
            if value == "" {
                value = "localhost"
            }
        case "DB_NAME", "DB_USER", "DB_PASSWORD":
            if value == "" {
                fmt.Fprintf(os.Stderr, "%s env variable is not set or empty\n", name)
                os.Exit(1)
            }
        }
        return value
    }

    dsn := os.Expand("${DB_USER}:${DB_PASSWORD}@tcp(${DB_HOST}:3306)/${DB_NAME}", mapper)
    db, err := sqlx.Open("mysql", dsn)
    if err != nil {
        fmt.Fprintf(os.Stderr, "sqlx.Open failed: %v\n", err)
        os.Exit(1)
    }
    defer db.Close()

    if err = db.Ping(); err != nil {
        fmt.Fprintf(os.Stderr, "Ping failed: could not connect to database: %v\n", err)
        os.Exit(1)
    }

    r := chi.NewRouter()
    registerRoutes(r, db)
    registerCustomRoutes(r, db)

    port := os.Getenv("PORT")
    if port == "" {
        port = "3000"
    }

    fmt.Println("Listen on " + port)
    err = http.ListenAndServe(":"+port, r)
    fmt.Fprintf(os.Stderr, "ListenAndServe failed: %v\n", err)
    os.Exit(1)
}