some fixes for docker and migrations

service_a/internal/app/db.go

@@ -2,8 +2,16 @@ package app
 
 import (
 	"context"
+	"database/sql"
+	"embed"
+	"errors"
+	"fmt"
 	"log/slog"
+	"os"
 
+	mig "github.com/golang-migrate/migrate/v4"
+	_ "github.com/golang-migrate/migrate/v4/database/postgres"
+	"github.com/golang-migrate/migrate/v4/source/iofs"
 	"github.com/jackc/pgx/v5/pgxpool"
 	_ "github.com/jackc/pgx/v5/stdlib"
 )
@@ -22,3 +30,36 @@ func NewPGXPool(datasource string) *pgxpool.Pool {
 	slog.Info("connected to database", "datasource", datasource)
 	return dbPool
 }
+
+func Migrate(database embed.FS) {
+	dbConn, err := sql.Open("pgx", os.Getenv("DATASOURCE"))
+	if err != nil {
+		slog.Error("error opening database connection", "error", err)
+		return
+	}
+	defer dbConn.Close()
+
+	d, err := iofs.New(database, "database/migrations")
+	if err != nil {
+		slog.Error("error creating migration source", "error", err)
+		return
+	}
+
+	m, err := mig.NewWithSourceInstance("iofs", d, fmt.Sprintf("postgres://%s:%s@%s", os.Getenv("POSTGRES_USER"), os.Getenv("POSTGRES_PASSWORD"), os.Getenv("DSN")))
+	if err != nil {
+		slog.Error("error creating migration instance", "error", err)
+		return
+	}
+
+	err = m.Up()
+	if err != nil && !errors.Is(err, mig.ErrNoChange) {
+		slog.Error("cannot migrate", "error", err)
+		panic(err)
+	}
+	if errors.Is(err, mig.ErrNoChange) {
+		slog.Info("migration has no changes")
+		return
+	}
+
+	slog.Info("migration done")
+}