awesome-compose/nginx-golang-postgres/backend/main.go

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package main
import (
"database/sql"
"encoding/json"
"fmt"
"io/ioutil"
"log"
"net/http"
"os"
"time"
"github.com/gorilla/handlers"
"github.com/gorilla/mux"
_ "github.com/lib/pq"
)
func connect() (*sql.DB, error) {
bin, err := ioutil.ReadFile("/run/secrets/db-password")
if err != nil {
return nil, err
}
return sql.Open("postgres", fmt.Sprintf("postgres://postgres:%s@db:5432/example?sslmode=disable", string(bin)))
}
func blogHandler(w http.ResponseWriter, r *http.Request) {
db, err := connect()
if err != nil {
w.WriteHeader(500)
return
}
defer db.Close()
rows, err := db.Query("SELECT title FROM blog")
if err != nil {
w.WriteHeader(500)
return
}
var titles []string
for rows.Next() {
var title string
err = rows.Scan(&title)
titles = append(titles, title)
}
json.NewEncoder(w).Encode(titles)
}
func main() {
log.Print("Prepare db...")
if err := prepare(); err != nil {
log.Fatal(err)
}
log.Print("Listening 8000")
r := mux.NewRouter()
r.HandleFunc("/", blogHandler)
log.Fatal(http.ListenAndServe(":8000", handlers.LoggingHandler(os.Stdout, r)))
}
func prepare() error {
db, err := connect()
if err != nil {
return err
}
defer db.Close()
for i := 0; i < 60; i++ {
if err := db.Ping(); err == nil {
break
}
time.Sleep(time.Second)
}
if _, err := db.Exec("DROP TABLE IF EXISTS blog"); err != nil {
return err
}
if _, err := db.Exec("CREATE TABLE IF NOT EXISTS blog (id SERIAL, title VARCHAR)"); err != nil {
return err
}
for i := 0; i < 5; i++ {
if _, err := db.Exec("INSERT INTO blog (title) VALUES ($1);", fmt.Sprintf("Blog post #%d", i)); err != nil {
return err
}
}
return nil
}