chore: sync from fn-registry agent

datafactory/datafactory.go

@@ -0,0 +1,77 @@
+// Package datafactory opens and migrates data_factory.db. It is consumed by
+// projects/fn_monitoring/apps/sqlite_api to expose REST + WS endpoints over
+// the data_factory schema (nodes, connections, runs, databases).
+//
+// The C++ app in apps/data_factory (main.cpp) does NOT depend on this
+// package. The Go subpackage lives in apps/data_factory/datafactory/ so it
+// does not collide with main.cpp at the Go-toolchain level.
+//
+// Migrations are read from disk at runtime (apps/data_factory/migrations/
+// relative to FN_REGISTRY_ROOT, or via an explicit migrationsDir argument).
+// This keeps the SQL as the single source of truth — the C++ side reads
+// the same files via its own bridge.
+package datafactory
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+// Open opens data_factory.db at dbPath (creating the file and the parent
+// directory if needed) and applies every *.sql under migrationsDir in
+// lexical order. Idempotent — re-running on an already-migrated DB is a
+// no-op (duplicate-column / already-exists errors are tolerated).
+// Returns a RW *sql.DB; callers are responsible for Close().
+func Open(dbPath, migrationsDir string) (*sql.DB, error) {
+	if err := os.MkdirAll(filepath.Dir(dbPath), 0o755); err != nil {
+		return nil, fmt.Errorf("datafactory: mkdir %s: %w", filepath.Dir(dbPath), err)
+	}
+	dsn := dbPath + "?_journal_mode=WAL&_busy_timeout=5000&_foreign_keys=on"
+	db, err := sql.Open("sqlite3", dsn)
+	if err != nil {
+		return nil, fmt.Errorf("datafactory: open %s: %w", dbPath, err)
+	}
+	if err := db.Ping(); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("datafactory: ping %s: %w", dbPath, err)
+	}
+	if err := applyMigrations(db, migrationsDir); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("datafactory: migrate: %w", err)
+	}
+	return db, nil
+}
+
+func applyMigrations(conn *sql.DB, dir string) error {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return fmt.Errorf("read migrations dir %s: %w", dir, err)
+	}
+	names := make([]string, 0, len(entries))
+	for _, e := range entries {
+		if !e.IsDir() && strings.HasSuffix(e.Name(), ".sql") {
+			names = append(names, e.Name())
+		}
+	}
+	sort.Strings(names)
+	for _, n := range names {
+		b, err := os.ReadFile(filepath.Join(dir, n))
+		if err != nil {
+			return fmt.Errorf("%s: read: %w", n, err)
+		}
+		if _, err := conn.Exec(string(b)); err != nil {
+			if strings.Contains(err.Error(), "duplicate column") ||
+				strings.Contains(err.Error(), "already exists") {
+				continue
+			}
+			return fmt.Errorf("%s: %w", n, err)
+		}
+	}
+	return nil
+}