diff --git a/driver.go b/driver.go
index a9b7891..d7c3cb7 100644
--- a/driver.go
+++ b/driver.go
@@ -12,13 +12,11 @@ type Driver interface {
 	// internal reference to that connection for later use. This library might
 	// call this method multiple times, so use the internal reference if it's
 	// present instead of reconnecting to the database.
-	Connect() (*sql.DB, error)
+	Connect(dsn string) (*sql.DB, error)
 	// Close should check if there's an internal reference to a database
 	// connection (a *sql.DB) and if it's present, close it. Then reset the
 	// internal reference to that connection to nil.
 	Close() error
-	// DSN returns data source name info, ie: how do I connect?
-	DSN() DSN
 
 	// AppliedVersions queries the schema migrations table for migration
 	// versions that have been executed against the database. If the schema
@@ -39,43 +37,6 @@ type Driver interface {
 	UpdateSchemaMigrations(dir Direction, version string) error
 }
 
-// NewDriver initializes a Driver implementation by name and connection
-// parameters.
-func NewDriver(dsn DSN, migConf *MigrationsConf) (driver Driver, err error) {
-	return dsn.NewDriver(migConf)
-}
-
-// DSN generates a data source name or connection URL for DB connections. The
-// output will be passed to the standard library's sql.Open method.
-type DSN interface {
-	// Boot takes inputs from the host environment so it can create a Driver.
-	//
-	// Deprecated: Set the DB_DSN environment variable instead of using this.
-	Boot(ConnectionParams) error
-	// NewDriver calls the constructor of the corresponding Driver.
-	NewDriver(*MigrationsConf) (Driver, error)
-	// String uses connection parameters to form the data source name.
-	String() string
-}
-
-// ConnectionParams is what to use when initializing a DSN.
-//
-// Deprecated: Set the DB_DSN environment variable instead of using this.
-type ConnectionParams struct {
-	Encoding string // Encoding is the client encoding for the connection.
-	Host     string // Host is the name of the host to connect to.
-	Name     string // Name is the database name.
-	Pass     string // Pass is the password to use for the connection.
-	Port     string // Port is the connection port.
-	User     string // User is the name of the user to connect as.
-}
-
-// MigrationsConf is intended to lend customizations such as specifying the path
-// to the migration files.
-type MigrationsConf struct {
-	PathToFiles string `json:"path_to_files"`
-}
-
 // AppliedVersions represents an iterative list of migrations that have been run
 // against the database and have been recorded in the schema migrations table.
 // It's enough to convert a *sql.Rows struct when implementing the Driver
diff --git a/drivers/mysql/godfish/main.go b/drivers/mysql/godfish/main.go
index 22dcb40..a2ced4d 100644
--- a/drivers/mysql/godfish/main.go
+++ b/drivers/mysql/godfish/main.go
@@ -9,9 +9,7 @@ import (
 )
 
 func main() {
-	var dsn mysql.DSN
-	err := commands.Run(&dsn)
-	if err != nil {
+	if err := commands.Run(mysql.NewDriver()); err != nil {
 		log.Println(err)
 		os.Exit(1)
 	}
diff --git a/drivers/mysql/mysql.go b/drivers/mysql/mysql.go
index c25851d..c513f8e 100644
--- a/drivers/mysql/mysql.go
+++ b/drivers/mysql/mysql.go
@@ -3,7 +3,6 @@ package mysql
 import (
 	"database/sql"
 	"fmt"
-	"os"
 	"regexp"
 	"strings"
 
@@ -11,56 +10,21 @@ import (
 	"github.com/rafaelespinoza/godfish"
 )
 
-// DSN implements the godfish.DSN interface and defines keys, values needed to
-// connect to a mysql database.
-type DSN struct {
-	godfish.ConnectionParams
-}
-
-var _ godfish.DSN = (*DSN)(nil)
-
-// Boot initializes the DSN from environment inputs.
-func (p *DSN) Boot(params godfish.ConnectionParams) error {
-	p.ConnectionParams = params
-	return nil
-}
-
 // NewDriver creates a new mysql driver.
-func (p *DSN) NewDriver(migConf *godfish.MigrationsConf) (godfish.Driver, error) {
-	return newMySQL(*p)
-}
-
-// String generates a data source name (or connection URL) based on the fields.
-func (p *DSN) String() string {
-	return os.Getenv("DB_DSN")
-}
+func NewDriver() godfish.Driver { return &driver{} }
 
 // driver implements the godfish.Driver interface for mysql databases.
 type driver struct {
 	connection *sql.DB
-	dsn        DSN
-}
-
-var _ godfish.Driver = (*driver)(nil)
-
-func newMySQL(dsn DSN) (*driver, error) {
-	if dsn.Host == "" {
-		dsn.Host = "localhost"
-	}
-	if dsn.Port == "" {
-		dsn.Port = "3306"
-	}
-	return &driver{dsn: dsn}, nil
 }
 
-func (d *driver) Name() string     { return "mysql" }
-func (d *driver) DSN() godfish.DSN { return &d.dsn }
-func (d *driver) Connect() (conn *sql.DB, err error) {
+func (d *driver) Name() string { return "mysql" }
+func (d *driver) Connect(dsn string) (conn *sql.DB, err error) {
 	if d.connection != nil {
 		conn = d.connection
 		return
 	}
-	if conn, err = sql.Open(d.Name(), d.DSN().String()); err != nil {
+	if conn, err = sql.Open(d.Name(), dsn); err != nil {
 		return
 	}
 	d.connection = conn
diff --git a/drivers/mysql/mysql_test.go b/drivers/mysql/mysql_test.go
index e0854f9..e8b8ace 100644
--- a/drivers/mysql/mysql_test.go
+++ b/drivers/mysql/mysql_test.go
@@ -8,5 +8,5 @@ import (
 )
 
 func Test(t *testing.T) {
-	internal.RunDriverTests(t, &mysql.DSN{})
+	internal.RunDriverTests(t, mysql.NewDriver())
 }
diff --git a/drivers/postgres/godfish/main.go b/drivers/postgres/godfish/main.go
index ad60579..9ed9fa4 100644
--- a/drivers/postgres/godfish/main.go
+++ b/drivers/postgres/godfish/main.go
@@ -9,9 +9,7 @@ import (
 )
 
 func main() {
-	var dsn postgres.DSN
-	err := commands.Run(&dsn)
-	if err != nil {
+	if err := commands.Run(postgres.NewDriver()); err != nil {
 		log.Println(err)
 		os.Exit(1)
 	}
diff --git a/drivers/postgres/postgres.go b/drivers/postgres/postgres.go
index 57c566b..d594b46 100644
--- a/drivers/postgres/postgres.go
+++ b/drivers/postgres/postgres.go
@@ -2,62 +2,26 @@ package postgres
 
 import (
 	"database/sql"
-	"os"
 
 	"github.com/lib/pq"
 	"github.com/rafaelespinoza/godfish"
 )
 
-// DSN implements the godfish.DSN interface and defines keys, values needed to
-// connect to a postgres database.
-type DSN struct {
-	godfish.ConnectionParams
-}
-
-var _ godfish.DSN = (*DSN)(nil)
-
-// Boot initializes the DSN from environment inputs.
-func (p *DSN) Boot(params godfish.ConnectionParams) error {
-	p.ConnectionParams = params
-	return nil
-}
-
 // NewDriver creates a new postgres driver.
-func (p *DSN) NewDriver(migConf *godfish.MigrationsConf) (godfish.Driver, error) {
-	return newPostgres(*p)
-}
-
-// String generates a data source name (or connection URL) based on the fields.
-func (p *DSN) String() string {
-	return os.Getenv("DB_DSN")
-}
+func NewDriver() godfish.Driver { return &driver{} }
 
 // driver implements the Driver interface for postgres databases.
 type driver struct {
 	connection *sql.DB
-	dsn        DSN
-}
-
-var _ godfish.Driver = (*driver)(nil)
-
-func newPostgres(dsn DSN) (*driver, error) {
-	if dsn.Host == "" {
-		dsn.Host = "localhost"
-	}
-	if dsn.Port == "" {
-		dsn.Port = "5432"
-	}
-	return &driver{dsn: dsn}, nil
 }
 
-func (d *driver) Name() string     { return "postgres" }
-func (d *driver) DSN() godfish.DSN { return &d.dsn }
-func (d *driver) Connect() (conn *sql.DB, err error) {
+func (d *driver) Name() string { return "postgres" }
+func (d *driver) Connect(dsn string) (conn *sql.DB, err error) {
 	if d.connection != nil {
 		conn = d.connection
 		return
 	}
-	if conn, err = sql.Open(d.Name(), d.DSN().String()); err != nil {
+	if conn, err = sql.Open(d.Name(), dsn); err != nil {
 		return
 	}
 	d.connection = conn
diff --git a/drivers/postgres/postgres_test.go b/drivers/postgres/postgres_test.go
index bfce968..e41d8df 100644
--- a/drivers/postgres/postgres_test.go
+++ b/drivers/postgres/postgres_test.go
@@ -8,5 +8,5 @@ import (
 )
 
 func Test(t *testing.T) {
-	internal.RunDriverTests(t, &postgres.DSN{})
+	internal.RunDriverTests(t, postgres.NewDriver())
 }
diff --git a/godfish.go b/godfish.go
index a4c869c..e653443 100644
--- a/godfish.go
+++ b/godfish.go
@@ -14,7 +14,16 @@ import (
 
 // Migrate executes all migrations at directoryPath in the specified direction.
 func Migrate(driver Driver, directoryPath string, direction Direction, finishAtVersion string) (err error) {
-	var migrations []Migration
+	var (
+		dsn        string
+		migrations []Migration
+	)
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
+		return
+	}
 	defer driver.Close()
 
 	if finishAtVersion == "" && direction == DirForward {
@@ -23,9 +32,6 @@ func Migrate(driver Driver, directoryPath string, direction Direction, finishAtV
 		finishAtVersion = minVersion
 	}
 
-	if _, err = driver.Connect(); err != nil {
-		return
-	}
 	finder := migrationFinder{
 		direction:       direction,
 		directoryPath:   directoryPath,
@@ -57,17 +63,25 @@ var (
 // ApplyMigration runs a migration at directoryPath with the specified version
 // and direction.
 func ApplyMigration(driver Driver, directoryPath string, direction Direction, version string) (err error) {
-	var mig Migration
-	var pathToFile string
+	var (
+		dsn        string
+		pathToFile string
+		mig        Migration
+	)
+
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
+		return
+	}
 	defer driver.Close()
 
 	if direction == DirUnknown {
 		err = fmt.Errorf("unknown Direction %q", direction)
 		return
 	}
-	if _, err = driver.Connect(); err != nil {
-		return
-	}
+
 	if version == "" {
 		// attempt to find the next version to apply in the direction
 		var limit string
@@ -183,7 +197,11 @@ func runMigration(driver Driver, pathToFile string, mig Migration) (err error) {
 // the database. Running any migration will create the table, so you don't
 // usually need to call this function.
 func CreateSchemaMigrationsTable(driver Driver) (err error) {
-	if _, err = driver.Connect(); err != nil {
+	var dsn string
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
 		return err
 	}
 	defer driver.Close()
@@ -192,7 +210,11 @@ func CreateSchemaMigrationsTable(driver Driver) (err error) {
 
 // Info displays the outputs of various helper functions.
 func Info(driver Driver, directoryPath string, direction Direction, finishAtVersion string) (err error) {
-	if _, err = driver.Connect(); err != nil {
+	var dsn string
+	if dsn, err = getDSN(); err != nil {
+		return
+	}
+	if _, err = driver.Connect(dsn); err != nil {
 		return err
 	}
 	defer driver.Close()
@@ -206,6 +228,11 @@ func Info(driver Driver, directoryPath string, direction Direction, finishAtVers
 	return
 }
 
+// Config is for various runtime settings.
+type Config struct {
+	PathToFiles string `json:"path_to_files"`
+}
+
 // Init creates a configuration file at pathToFile unless it already exists.
 func Init(pathToFile string) (err error) {
 	_, err = os.Stat(pathToFile)
@@ -218,7 +245,7 @@ func Init(pathToFile string) (err error) {
 	}
 
 	var data []byte
-	if data, err = json.MarshalIndent(MigrationsConf{}, "", "\t"); err != nil {
+	if data, err = json.MarshalIndent(Config{}, "", "\t"); err != nil {
 		return err
 	}
 	return os.WriteFile(
@@ -454,3 +481,13 @@ func printMigrations(migrations []Migration) {
 		fmt.Printf("\t%-20s | %-s\n", mig.Version().String(), makeMigrationFilename(mig))
 	}
 }
+
+const dsnKey = "DB_DSN"
+
+func getDSN() (dsn string, err error) {
+	dsn = os.Getenv(dsnKey)
+	if dsn == "" {
+		err = fmt.Errorf("missing environment variable: %s", dsnKey)
+	}
+	return
+}
diff --git a/godfish_test.go b/godfish_test.go
index 9465440..964d622 100644
--- a/godfish_test.go
+++ b/godfish_test.go
@@ -33,7 +33,7 @@ func TestInit(t *testing.T) {
 	if err = godfish.Init(pathToFile); err != nil {
 		t.Fatalf("something else is wrong with setup; %v", err)
 	}
-	var conf godfish.MigrationsConf
+	var conf godfish.Config
 	if data, err := os.ReadFile(pathToFile); err != nil {
 		t.Fatal(err)
 	} else if err = json.Unmarshal(data, &conf); err != nil {
@@ -54,7 +54,7 @@ func TestInit(t *testing.T) {
 	if err := godfish.Init(pathToFile); err != nil {
 		t.Fatal(err)
 	}
-	var conf2 godfish.MigrationsConf
+	var conf2 godfish.Config
 	if data, err := os.ReadFile(pathToFile); err != nil {
 		t.Fatal(err)
 	} else if err = json.Unmarshal(data, &conf2); err != nil {
diff --git a/internal/commands/commands.go b/internal/commands/commands.go
index a9097d6..c2d3f66 100644
--- a/internal/commands/commands.go
+++ b/internal/commands/commands.go
@@ -17,7 +17,7 @@ type arguments struct {
 	Conf       string
 	Debug      bool
 	Direction  string
-	DSN        godfish.DSN
+	Driver     godfish.Driver
 	Files      string
 	Name       string
 	Reversible bool
@@ -32,9 +32,9 @@ var (
 )
 
 // Run does all the CLI things.
-func Run(dsn godfish.DSN) (err error) {
+func Run(driver godfish.Driver) (err error) {
 	flag.Parse()
-	args.DSN = dsn
+	args.Driver = driver
 
 	var cmd *subcommand
 
@@ -123,7 +123,7 @@ func initSubcommand(positionalArgs []string, a *arguments) (subcmd *subcommand,
 	}
 
 	// Read configuration file, if present. Negotiate with Args.
-	var conf godfish.MigrationsConf
+	var conf godfish.Config
 	if data, ierr := os.ReadFile(a.Conf); ierr != nil {
 		// probably no config file present, rely on Args instead.
 	} else if ierr = json.Unmarshal(data, &conf); ierr != nil {
@@ -225,12 +225,8 @@ var subcommands = map[string]*subcommand{
 			return flags
 		},
 		run: func(a arguments) error {
-			driver, err := bootDriver(a.DSN)
-			if err != nil {
-				return err
-			}
 			direction := whichDirection(a)
-			return godfish.Info(driver, a.Files, direction, a.Version)
+			return godfish.Info(a.Driver, a.Files, direction, a.Version)
 		},
 	},
 	"init": &subcommand{
@@ -281,13 +277,8 @@ var subcommands = map[string]*subcommand{
 			return flags
 		},
 		run: func(a arguments) error {
-			driver, err := bootDriver(a.DSN)
-			if err != nil {
-				return err
-			}
-
-			err = godfish.Migrate(
-				driver,
+			err := godfish.Migrate(
+				a.Driver,
 				a.Files,
 				godfish.DirForward,
 				a.Version,
@@ -311,24 +302,11 @@ var subcommands = map[string]*subcommand{
 			return flags
 		},
 		run: func(a arguments) error {
-			driver, err := bootDriver(a.DSN)
+			err := godfish.ApplyMigration(a.Driver, a.Files, godfish.DirReverse, "")
 			if err != nil {
 				return err
 			}
-			if err = godfish.ApplyMigration(
-				driver,
-				a.Files,
-				godfish.DirReverse,
-				"",
-			); err != nil {
-				return err
-			}
-			return godfish.ApplyMigration(
-				driver,
-				a.Files,
-				godfish.DirForward,
-				"",
-			)
+			return godfish.ApplyMigration(a.Driver, a.Files, godfish.DirForward, "")
 		},
 	},
 	"rollback": &subcommand{
@@ -356,20 +334,17 @@ var subcommands = map[string]*subcommand{
 			return flags
 		},
 		run: func(a arguments) error {
-			driver, err := bootDriver(a.DSN)
-			if err != nil {
-				return err
-			}
+			var err error
 			if a.Version == "" {
 				err = godfish.ApplyMigration(
-					driver,
+					a.Driver,
 					a.Files,
 					godfish.DirReverse,
 					a.Version,
 				)
 			} else {
 				err = godfish.Migrate(
-					driver,
+					a.Driver,
 					a.Files,
 					godfish.DirReverse,
 					a.Version,
@@ -381,21 +356,6 @@ var subcommands = map[string]*subcommand{
 	"version": _Version,
 }
 
-func bootDriver(dsn godfish.DSN) (driver godfish.Driver, err error) {
-	connParams := godfish.ConnectionParams{
-		Host: os.Getenv("DB_HOST"),
-		Name: os.Getenv("DB_NAME"),
-		Pass: os.Getenv("DB_PASSWORD"),
-		Port: os.Getenv("DB_PORT"),
-		User: os.Getenv("DB_USER"),
-	}
-	if err = dsn.Boot(connParams); err != nil {
-		return
-	}
-	driver, err = dsn.NewDriver(nil)
-	return
-}
-
 func whichDirection(a arguments) (direction godfish.Direction) {
 	direction = godfish.DirForward
 	d := strings.ToLower(a.Direction)
diff --git a/internal/stub/driver.go b/internal/stub/driver.go
index 71b984d..2b06e72 100644
--- a/internal/stub/driver.go
+++ b/internal/stub/driver.go
@@ -10,7 +10,6 @@ import (
 )
 
 type Driver struct {
-	dsn             DSN
 	connection      *sql.DB
 	appliedVersions godfish.AppliedVersions
 	err             error
@@ -19,10 +18,9 @@ type Driver struct {
 
 var _ godfish.Driver = (*Driver)(nil)
 
-func (d *Driver) Name() string              { return "stub" }
-func (d *Driver) Connect() (*sql.DB, error) { return d.connection, d.err }
-func (d *Driver) Close() error              { return d.err }
-func (d *Driver) DSN() godfish.DSN          { return &d.dsn }
+func (d *Driver) Name() string                        { return "stub" }
+func (d *Driver) Connect(dsn string) (*sql.DB, error) { return d.connection, d.err }
+func (d *Driver) Close() error                        { return d.err }
 func (d *Driver) CreateSchemaMigrationsTable() error {
 	if d.appliedVersions == nil {
 		d.appliedVersions = MakeAppliedVersions()
@@ -77,19 +75,6 @@ func (d *Driver) Teardown() {
 	d.appliedVersions = MakeAppliedVersions()
 }
 
-type DSN struct{ godfish.ConnectionParams }
-
-func (d DSN) Boot(params godfish.ConnectionParams) error {
-	d.ConnectionParams = params
-	return nil
-}
-func (d DSN) NewDriver(migConf *godfish.MigrationsConf) (godfish.Driver, error) {
-	return &Driver{dsn: d}, nil
-}
-func (d DSN) String() string { return "this://is.a/test" }
-
-var _ godfish.DSN = (*DSN)(nil)
-
 type AppliedVersions struct {
 	counter  int
 	versions []string
diff --git a/internal/stub/driver_test.go b/internal/stub/driver_test.go
index 1df8285..660910e 100644
--- a/internal/stub/driver_test.go
+++ b/internal/stub/driver_test.go
@@ -8,5 +8,6 @@ import (
 )
 
 func Test(t *testing.T) {
-	internal.RunDriverTests(t, &stub.DSN{})
+	var driver stub.Driver
+	internal.RunDriverTests(t, &driver)
 }
diff --git a/internal/test.go b/internal/test.go
index 4496019..072ad99 100644
--- a/internal/test.go
+++ b/internal/test.go
@@ -13,30 +13,7 @@ import (
 )
 
 // RunDriverTests tests an implementation of the godfish.Driver interface.
-func RunDriverTests(t *testing.T, dsn godfish.DSN) {
-	t.Helper()
-	connParams := godfish.ConnectionParams{
-		Encoding: "UTF8",
-		Host:     os.Getenv("DB_HOST"),
-		Name:     "godfish_test",
-		Pass:     os.Getenv("DB_PASSWORD"),
-		Port:     os.Getenv("DB_PORT"),
-		User:     os.Getenv("DB_USER"),
-	}
-	if connParams.Host == "" {
-		connParams.Host = "localhost"
-	}
-	if connParams.User == "" {
-		connParams.User = "godfish"
-	}
-	if err := dsn.Boot(connParams); err != nil {
-		t.Fatal(err)
-	}
-	driver, err := godfish.NewDriver(dsn, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-
+func RunDriverTests(t *testing.T, driver godfish.Driver) {
 	// Tests for creating the schema migrations table are deliberately not
 	// included. It should be called as needed by other library functions.
 
@@ -605,6 +582,16 @@ func RunDriverTests(t *testing.T, dsn godfish.DSN) {
 	})
 }
 
+const dsnKey = "DB_DSN"
+
+func mustDSN() string {
+	dsn := os.Getenv(dsnKey)
+	if dsn == "" {
+		panic("empty environment variable " + dsnKey)
+	}
+	return dsn
+}
+
 // Magic option values for test setup and teardown.
 const (
 	_SkipMigration = "-"
@@ -628,7 +615,7 @@ func setup(driver godfish.Driver, testName string, stubs []testDriverStub, migra
 // teardown clears state after running a test.
 func teardown(driver godfish.Driver, path string, tablesToDrop ...string) {
 	var err error
-	if _, err = driver.Connect(); err != nil {
+	if _, err = driver.Connect(mustDSN()); err != nil {
 		panic(err)
 	}
 
@@ -824,7 +811,7 @@ func generateMigrationFiles(pathToTestDir string, stubs []testDriverStub) error
 func collectAppliedVersions(driver godfish.Driver) (out []string, err error) {
 	// Collect output of AppliedVersions.
 	// Reconnect here because ApplyMigration closes the connection.
-	if _, err = driver.Connect(); err != nil {
+	if _, err = driver.Connect(mustDSN()); err != nil {
 		return
 	}
 	defer driver.Close()