feat: support fetching migration history table to files (#2113)

feat: support fetching migration history to local

cmd/migration.go

@@ -8,6 +8,7 @@ import (
 	"github.com/spf13/afero"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
+	"github.com/supabase/cli/internal/migration/fetch"
 	"github.com/supabase/cli/internal/migration/list"
 	"github.com/supabase/cli/internal/migration/new"
 	"github.com/supabase/cli/internal/migration/repair"
@@ -88,6 +89,14 @@ var (
 			fmt.Println("Local database is up to date.")
 		},
 	}
+
+	migrationFetchCmd = &cobra.Command{
+		Use:   "fetch",
+		Short: "Fetch migration files from history table",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return fetch.Run(cmd.Context(), flags.DbConfig, afero.NewOsFs())
+		},
+	}
 )
 
 func init() {
@@ -132,6 +141,13 @@ func init() {
 	upFlags.Bool("local", true, "Applies pending migrations to the local database.")
 	migrationUpCmd.MarkFlagsMutuallyExclusive("db-url", "linked", "local")
 	migrationCmd.AddCommand(migrationUpCmd)
+	// Build up command
+	fetchFlags := migrationFetchCmd.Flags()
+	fetchFlags.String("db-url", "", "Fetches migrations from the database specified by the connection string (must be percent-encoded).")
+	fetchFlags.Bool("linked", true, "Fetches migration history from the linked project.")
+	fetchFlags.Bool("local", false, "Fetches migration history from the local database.")
+	migrationFetchCmd.MarkFlagsMutuallyExclusive("db-url", "linked", "local")
+	migrationCmd.AddCommand(migrationFetchCmd)
 	// Build new command
 	migrationCmd.AddCommand(migrationNewCmd)
 	rootCmd.AddCommand(migrationCmd)

internal/migration/fetch/fetch.go

@@ -0,0 +1,52 @@
+package fetch
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"github.com/go-errors/errors"
+	"github.com/jackc/pgconn"
+	"github.com/jackc/pgx/v4"
+	"github.com/spf13/afero"
+	"github.com/supabase/cli/internal/migration/history"
+	"github.com/supabase/cli/internal/utils"
+)
+
+func Run(ctx context.Context, config pgconn.Config, fsys afero.Fs, options ...func(*pgx.ConnConfig)) error {
+	if err := utils.MkdirIfNotExistFS(fsys, utils.MigrationsDir); err != nil {
+		return err
+	}
+	if empty, err := afero.IsEmpty(fsys, utils.MigrationsDir); err != nil {
+		return errors.Errorf("failed to read migrations: %w", err)
+	} else if !empty {
+		console := utils.NewConsole()
+		title := fmt.Sprintf("Do you want to overwrite existing files in %s directory?", utils.Bold(utils.MigrationsDir))
+		if !console.PromptYesNo(title, true) {
+			return context.Canceled
+		}
+	}
+	result, err := fetchMigrationHistory(ctx, config, options...)
+	if err != nil {
+		return err
+	}
+	for _, r := range result {
+		name := fmt.Sprintf("%s_%s.sql", r.Version, r.Name)
+		path := filepath.Join(utils.MigrationsDir, name)
+		contents := strings.Join(r.Statements, ";\n") + ";\n"
+		if err := afero.WriteFile(fsys, path, []byte(contents), 0644); err != nil {
+			return errors.Errorf("failed to write migration: %w", err)
+		}
+	}
+	return nil
+}
+
+func fetchMigrationHistory(ctx context.Context, config pgconn.Config, options ...func(*pgx.ConnConfig)) ([]history.SchemaMigration, error) {
+	conn, err := utils.ConnectByConfig(ctx, config, options...)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close(context.Background())
+	return history.ReadMigrationTable(ctx, conn)
+}

internal/migration/history/history.go

@@ -6,6 +6,7 @@ import (
 	"github.com/go-errors/errors"
 	"github.com/jackc/pgconn"
 	"github.com/jackc/pgx/v4"
+	"github.com/supabase/cli/internal/utils/pgxv5"
 )
 
 const (
@@ -18,8 +19,15 @@ const (
 	DELETE_MIGRATION_VERSION = "DELETE FROM supabase_migrations.schema_migrations WHERE version = ANY($1)"
 	DELETE_MIGRATION_BEFORE  = "DELETE FROM supabase_migrations.schema_migrations WHERE version <= $1"
 	TRUNCATE_VERSION_TABLE   = "TRUNCATE supabase_migrations.schema_migrations"
+	SELECT_VERSION_TABLE     = "SELECT * FROM supabase_migrations.schema_migrations"
 )
 
+type SchemaMigration struct {
+	Version    string
+	Name       string
+	Statements []string
+}
+
 func CreateMigrationTable(ctx context.Context, conn *pgx.Conn) error {
 	// This must be run without prepared statements because each statement in the batch depends on
 	// the previous schema change. The lock timeout will be reset when implicit transaction ends.
@@ -34,3 +42,11 @@ func CreateMigrationTable(ctx context.Context, conn *pgx.Conn) error {
 	}
 	return nil
 }
+
+func ReadMigrationTable(ctx context.Context, conn *pgx.Conn) ([]SchemaMigration, error) {
+	rows, err := conn.Query(ctx, SELECT_VERSION_TABLE)
+	if err != nil {
+		return nil, errors.Errorf("failed to read migration table: %w", err)
+	}
+	return pgxv5.CollectRows[SchemaMigration](rows)
+}