refactor: reuse constants for redis db

go/internal/db/postgres.go

@@ -0,0 +1,44 @@
+package db
+
+import (
+	"context"
+	"log/slog"
+	"os"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+var db *pgxpool.Pool
+
+func Cleanup() {
+	db.Close()
+}
+
+func Pool() *pgxpool.Pool {
+	return db
+}
+
+func Init() {
+	connString := os.Getenv("LLINK_POSTGRES_CONNECTION_URL")
+	if connString == "" {
+		slog.Error("must provide LLINK_POSTGRES_CONNECTION_URL in env")
+		os.Exit(1)
+	}
+
+	dbpool, err := pgxpool.New(context.Background(), connString)
+	if err != nil {
+		slog.Error("unable to create connection pool", "error", err)
+		os.Exit(1)
+	}
+
+	var greeting string
+	err = dbpool.QueryRow(context.Background(), "select 'Hello, world!'").Scan(&greeting)
+	if err != nil {
+		slog.Error("queryRow failed", "error", err)
+		os.Exit(1)
+	}
+
+	slog.Info("successfully connected to database", "greeting", greeting)
+
+	db = dbpool
+}