Configuration

Everything has a sensible default, and everything can be swapped out through migrate.Configtype Config struct{ … }Config adjusts how migrations work., which you pass to Main or Up.

Field	Default	Purpose
Dir	migrations	The folder
VersionsDir, CodeDir	versions, code	The two folders inside it
FS, Embedded	none	Read from go:embed, always, or when the folder is missing
Source	files	Replace storage entirely
PerDialect	off	Keep each dialect's files in Dir/<dialect>
Name, Parse	0001_name.up.sql	Write and read file names, with migrate.Timestampedfunc Timestamped(n Next) stringTimestamped names files by time, as in 20261031120501_add_bio.up.sql, which avoids most version clashes between branches. built in
Render	schema.Scriptfunc Script(d Dialect, p *Plan) (string, error)Script writes a plan as a SQL file, with warnings as comments above the statements they concern.	Replace how a plan becomes SQL
HistoryTable, HistorySchema	ant_migrations	Where applied migrations are recorded
DSN	none	The fallback after --dsn and DATABASE_URL
Skip	none	Versions to leave unapplied
OutOfOrder	off	Let an older pending migration run
Ignore	none	Names for drift to overlook, such as legacy_* or users.handmade_idx
NoLock	off	Turn off the migration lock
SeedHooks	off	Run model hooks while seeding
Out, OnApply	quiet in Up	Progress text, and a callback per migration

Storage

Source lists migrations from anywhere, such as a table or an object store. Implement Store as well for the commands that write.

type Source interface {
	List(ctx context.Context) ([]migrate.Migration, error)
	Snapshot(ctx context.Context) ([]byte, error)
}

File names

Name chooses a new file's name, and Parse reads a version and name back.

SQL

Render receives the plan, as data, and can wrap the default.

config := migrate.Config{
	Render: func(plan *schema.Plan, d schema.Dialect) (string, error) {
		text, err := schema.Script(d, plan)

		return "SET lock_timeout = '5s';\n\n" + text, err
	},
}

See it tested: tests/features/migrations/source_test.go