[WIP] - goose schema command (postgres only)

cmd/goose/main.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/pressly/goose/v3"
 	"github.com/pressly/goose/v3/internal/cfg"
+	"github.com/pressly/goose/v3/internal/pgutil"
 )
 
 var (
@@ -137,6 +138,29 @@ func main() {
 	if *noVersioning {
 		options = append(options, goose.WithNoVersioning())
 	}
+
+	switch command {
+	case "schema":
+		if driver != "pgx" {
+			log.Fatalln("this command is only available for postgres")
+		}
+		connOptions, err := pgutil.NewConnectionOptions(dbstring)
+		if err != nil {
+			log.Fatalln(err)
+		}
+		var clean bool
+		if len(args) == 4 && args[3] == "--clean" { // LOL
+			clean = true
+		}
+		out, err := pgutil.DumpSchema(connOptions, clean)
+		if err != nil {
+			log.Fatalln(err)
+		}
+		// TODO(mf): dump to stdout or to a file?
+		fmt.Fprintln(os.Stdout, out)
+		return
+	}
+
 	if err := goose.RunWithOptions(
 		command,
 		db,

internal/pgutil/pgutil.go

@@ -0,0 +1,146 @@
+package pgutil
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+)
+
+func DumpSchema(options ConnectionOptions, clean bool) (string, error) {
+	var b bytes.Buffer
+	if err := dump(&b, options); err != nil {
+		return "", err
+	}
+	if clean {
+		return cleanup(&b)
+	}
+	return b.String(), nil
+}
+
+var matchIgnorePrefix = []string{
+	"--",
+	"COMMENT ON",
+	"REVOKE",
+	"GRANT",
+	"SET",
+	"ALTER DEFAULT PRIVILEGES",
+}
+
+var matchIgnoreContains = []string{
+	"ALTER DEFAULT PRIVILEGES",
+	"OWNER TO",
+}
+
+func ignore(input string) bool {
+	for _, v := range matchIgnorePrefix {
+		if strings.HasPrefix(input, v) {
+			return true
+		}
+	}
+	for _, v := range matchIgnoreContains {
+		if strings.Contains(input, v) {
+			return true
+		}
+	}
+	return false
+}
+
+var reAdjacentEmptyLines = regexp.MustCompile(`(?m)(\n){3,}`)
+
+func cleanup(r io.Reader) (string, error) {
+	var b strings.Builder
+	sc := bufio.NewScanner(r)
+	for sc.Scan() {
+		line := sc.Text()
+		if ignore(line) {
+			continue
+		}
+		if _, err := b.WriteString(line + "\n"); err != nil {
+			return "", fmt.Errorf("failed to write output: %w", err)
+		}
+	}
+	if err := sc.Err(); err != nil {
+		return "", err
+	}
+	result := reAdjacentEmptyLines.ReplaceAllString(b.String(), "\n\n")
+	return "\n" + strings.TrimSpace(result) + "\n", nil
+}
+
+func dump(w io.Writer, options ConnectionOptions) error {
+	pgDumpPath, err := exec.LookPath("pg_dump")
+	if err != nil && !errors.Is(err, exec.ErrNotFound) {
+		return err
+	}
+	if pgDumpPath != "" {
+		return runPgDump(w, pgDumpPath, options)
+	}
+	dockerPath, err := exec.LookPath("docker")
+	if err != nil && !errors.Is(err, exec.ErrNotFound) {
+		return err
+	}
+	if dockerPath != "" {
+		return runDockerPgDump(dockerPath)
+	}
+	return fmt.Errorf("failed to find at least one exectuable: pg_dump, docker")
+}
+
+type ConnectionOptions struct {
+	DBname   string
+	Username string
+	Host     string
+	Port     string
+	Password string
+}
+
+func NewConnectionOptions(raw string) (ConnectionOptions, error) {
+	var opt ConnectionOptions
+	u, err := url.Parse(raw)
+	if err != nil {
+		return opt, err
+	}
+	if u.User == nil {
+		return opt, fmt.Errorf("invalid postgres connection string: missing username and password information")
+	}
+	// TODO(mf): we could ask the user for password with a prompt here.
+	pass, ok := u.User.Password()
+	if !ok {
+		return opt, fmt.Errorf("invalid postgres connection string: missing password information")
+	}
+	opt.Username = u.User.Username()
+	opt.Password = pass
+	opt.Host = u.Hostname()
+	opt.Port = u.Port()
+	opt.DBname = strings.TrimPrefix(u.Path, "/")
+	// TODO(mf): What about u.RawQuery to get at options after the ? .."sslmode=disable"
+	return opt, nil
+}
+
+func (c ConnectionOptions) Args() []string {
+	return []string{
+		"--dbname=" + c.DBname,
+		"--host=" + c.Host,
+		"--port=" + c.Port,
+		"--username=" + c.Username,
+	}
+}
+
+func runPgDump(w io.Writer, pgDumpPath string, connOptions ConnectionOptions) error {
+	args := append(connOptions.Args(), "--schema-only")
+	cmd := exec.Command(pgDumpPath, args...)
+	cmd.Env = append(cmd.Env, "PGPASSWORD="+connOptions.Password)
+	cmd.Stdout = w
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+
+}
+
+func runDockerPgDump(dockerPath string) error {
+	return errors.New("unimplemented")
+}