feat(gl): add immutable postgres ledger storage

infrastructure/postgres/migrate.go

@@ -0,0 +1,75 @@
+package postgres
+
+import (
+	"context"
+	"embed"
+	"fmt"
+	"io/fs"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+//go:embed migrations/*.up.sql
+var migrationFiles embed.FS
+
+const migrationLockID int64 = 674301
+
+func Migrate(ctx context.Context, database Database) (err error) {
+	tx, err := database.Begin(ctx)
+	if err != nil {
+		return fmt.Errorf("begin migrations: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			_ = tx.Rollback(ctx)
+		}
+	}()
+
+	if _, err = tx.Exec(ctx, "SELECT pg_advisory_xact_lock($1)", migrationLockID); err != nil {
+		return fmt.Errorf("lock migrations: %w", err)
+	}
+	if _, err = tx.Exec(ctx, `CREATE TABLE IF NOT EXISTS ledger_schema_migrations (
+        version bigint PRIMARY KEY,
+        applied_at timestamptz NOT NULL DEFAULT clock_timestamp()
+    )`); err != nil {
+		return fmt.Errorf("create migration ledger: %w", err)
+	}
+
+	files, err := fs.Glob(migrationFiles, "migrations/*.up.sql")
+	if err != nil {
+		return fmt.Errorf("list migrations: %w", err)
+	}
+	sort.Strings(files)
+	for _, name := range files {
+		versionText := strings.SplitN(strings.TrimPrefix(name, "migrations/"), "_", 2)[0]
+		version, parseErr := strconv.ParseInt(versionText, 10, 64)
+		if parseErr != nil {
+			return fmt.Errorf("parse migration %s: %w", name, parseErr)
+		}
+
+		var applied bool
+		if err = tx.QueryRow(ctx, "SELECT EXISTS (SELECT 1 FROM ledger_schema_migrations WHERE version = $1)", version).Scan(&applied); err != nil {
+			return fmt.Errorf("check migration %s: %w", name, err)
+		}
+		if applied {
+			continue
+		}
+
+		contents, readErr := migrationFiles.ReadFile(name)
+		if readErr != nil {
+			return fmt.Errorf("read migration %s: %w", name, readErr)
+		}
+		if _, err = tx.Exec(ctx, string(contents)); err != nil {
+			return fmt.Errorf("apply migration %s: %w", name, err)
+		}
+		if _, err = tx.Exec(ctx, "INSERT INTO ledger_schema_migrations (version) VALUES ($1) ON CONFLICT DO NOTHING", version); err != nil {
+			return fmt.Errorf("record migration %s: %w", name, err)
+		}
+	}
+
+	if err = tx.Commit(ctx); err != nil {
+		return fmt.Errorf("commit migrations: %w", err)
+	}
+	return nil
+}