Accept basic configuration through environment variables

cmd/web/main.go

@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"log"
 	"net/http"
+	"net/url"
 	"os"
 	"time"
 	"vkane.cz/tinyquiz/pkg/model"
@@ -31,6 +32,40 @@ func setDefaultTemplateData(td *templateData) {
 }
 
 func main() {
+	var addr string
+	if env, ok := os.LookupEnv("TINYQUIZ_LISTEN"); ok {
+		addr = env
+	} else {
+		addr = "[::1]:8080"
+	}
+
+	var pgConnectionUri url.URL
+	pgConnectionUri.Scheme = "postgresql"
+	pgConnectionUri.Path = "/"
+	pgQuery := pgConnectionUri.Query()
+	if env, ok := os.LookupEnv("TINYQUIZ_PG_HOST"); ok {
+		pgQuery.Set("host", env)
+	} else {
+		pgQuery.Set("host", "127.0.0.1")
+	}
+	if env, ok := os.LookupEnv("TINYQUIZ_PG_DBNAME"); ok {
+		pgQuery.Set("dbname", env)
+	} else {
+		pgQuery.Set("dbname", "tinyquiz")
+	}
+	if env, ok := os.LookupEnv("TINYQUIZ_PG_USER"); ok {
+		pgQuery.Set("user", env)
+	}
+	if env, ok := os.LookupEnv("TINYQUIZ_PG_PASSWORD"); ok {
+		pgQuery.Set("password", env)
+	}
+	if _, ok := os.LookupEnv("TINYQUIZ_PG_ENABLESSL"); ok {
+		pgQuery.Set("sslmode", "verify-full")
+	} else {
+		pgQuery.Set("sslmode", "disable")
+	}
+	pgConnectionUri.RawQuery = pgQuery.Encode()
+
 	infoLog := log.New(os.Stdout, "INFO\t", log.Ldate|log.Ltime)
 	errorLog := log.New(os.Stderr, "ERROR\t", log.Ldate|log.Ltime|log.Lshortfile)
 
@@ -46,7 +81,7 @@ func main() {
 		errorLog.Fatal(err)
 	}
 
-	if c, err := ent.Open("postgres", "host='127.0.0.1' sslmode=disable dbname=tinyquiz"); err == nil {
+	if c, err := ent.Open("postgres", pgConnectionUri.String()); err == nil {
 		if err := c.Schema.Create(context.Background(), migrate.WithDropIndex(true), migrate.WithDropColumn(true)); err != nil {
 			errorLog.Fatal(err)
 		}
@@ -77,11 +112,11 @@ func main() {
 	mux.ServeFiles("/static/*filepath", http.Dir("./ui/static/"))
 
 	var srv = &http.Server{
-		Addr:     "127.0.0.1:8080",
+		Addr:     addr,
 		ErrorLog: errorLog,
 		Handler:  mux,
 	}
-	log.Println("Starting server on :8080")
+	log.Printf("Starting server on %s\n", addr)
 	err := srv.ListenAndServe()
 	log.Fatal(err)
 }