panel v0.9.1 — open-source game server manager

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

controller/internal/db/migrate.go

@@ -0,0 +1,95 @@
+package db
+
+import (
+	"context"
+	"embed"
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+//go:embed migrations/*.sql
+var migrationsFS embed.FS
+
+// migrateLockKey is the pg advisory-lock key serializing Migrate across
+// controllers sharing one database. Arbitrary but fixed: fnv-ish of
+// "panel:schema_migrations". Session-scoped (not transaction-scoped) so it
+// spans the whole multi-transaction run and releases on disconnect if the
+// process dies mid-migrate.
+const migrateLockKey int64 = 0x70616e656c6d6967 // "panelmig"
+
+// Migrate applies any pending SQL files in migrations/ in filename-sorted
+// order. Each file is wrapped in a transaction alongside its schema_migrations
+// insert so failure leaves the DB in a consistent state. A session-level
+// pg advisory lock serializes concurrent controllers: the second one blocks
+// here, then finds every version already recorded and no-ops.
+func Migrate(ctx context.Context, pool *pgxpool.Pool) error {
+	// Dedicated connection: session advisory locks belong to a connection,
+	// and pool.Exec could lock on one conn and unlock on another.
+	lockConn, err := pool.Acquire(ctx)
+	if err != nil {
+		return fmt.Errorf("acquire migrate lock conn: %w", err)
+	}
+	defer lockConn.Release()
+	if _, err := lockConn.Exec(ctx, `SELECT pg_advisory_lock($1)`, migrateLockKey); err != nil {
+		return fmt.Errorf("acquire migrate advisory lock: %w", err)
+	}
+	defer func() {
+		_, _ = lockConn.Exec(context.WithoutCancel(ctx), `SELECT pg_advisory_unlock($1)`, migrateLockKey)
+	}()
+
+	if _, err := pool.Exec(ctx, `CREATE TABLE IF NOT EXISTS schema_migrations (
+		version TEXT PRIMARY KEY,
+		applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+	)`); err != nil {
+		return fmt.Errorf("create schema_migrations: %w", err)
+	}
+
+	entries, err := migrationsFS.ReadDir("migrations")
+	if err != nil {
+		return fmt.Errorf("read embedded migrations: %w", err)
+	}
+	var files []string
+	for _, e := range entries {
+		if !e.IsDir() && strings.HasSuffix(e.Name(), ".sql") {
+			files = append(files, e.Name())
+		}
+	}
+	sort.Strings(files)
+
+	for _, name := range files {
+		var exists bool
+		if err := pool.QueryRow(ctx,
+			`SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version = $1)`, name,
+		).Scan(&exists); err != nil {
+			return fmt.Errorf("check %s: %w", name, err)
+		}
+		if exists {
+			continue
+		}
+
+		body, err := migrationsFS.ReadFile("migrations/" + name)
+		if err != nil {
+			return fmt.Errorf("read %s: %w", name, err)
+		}
+
+		tx, err := pool.Begin(ctx)
+		if err != nil {
+			return fmt.Errorf("begin tx for %s: %w", name, err)
+		}
+		if _, err := tx.Exec(ctx, string(body)); err != nil {
+			_ = tx.Rollback(ctx)
+			return fmt.Errorf("apply %s: %w", name, err)
+		}
+		if _, err := tx.Exec(ctx, `INSERT INTO schema_migrations(version) VALUES ($1)`, name); err != nil {
+			_ = tx.Rollback(ctx)
+			return fmt.Errorf("record %s: %w", name, err)
+		}
+		if err := tx.Commit(ctx); err != nil {
+			return fmt.Errorf("commit %s: %w", name, err)
+		}
+	}
+	return nil
+}