Better error message for database-url errors

db/pg/pg.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"net/url"
 	"strconv"
+	"strings"
 	"time"
 
 	_ "github.com/jackc/pgx/v5/stdlib" // PostgreSQL driver
@@ -28,6 +29,12 @@ func Open(dsn string) (*sql.DB, error) {
 	if err != nil {
 		return nil, fmt.Errorf("invalid database URL: %w", err)
 	}
+	switch u.Scheme {
+	case "postgres", "postgresql":
+		// OK
+	default:
+		return nil, fmt.Errorf("invalid database URL scheme %q, must be \"postgres\" or \"postgresql\" (URL: %s)", u.Scheme, censorPassword(u))
+	}
 	q := u.Query()
 	maxOpenConns, err := extractIntParam(q, paramMaxOpenConns, defaultMaxOpenConns)
 	if err != nil {
@@ -61,7 +68,7 @@ func Open(dsn string) (*sql.DB, error) {
 		db.SetConnMaxIdleTime(connMaxIdleTime)
 	}
 	if err := db.Ping(); err != nil {
-		return nil, fmt.Errorf("ping failed: %w", err)
+		return nil, fmt.Errorf("database ping failed (URL: %s): %w", censorPassword(u), err)
 	}
 	return db, nil
 }
@@ -79,6 +86,14 @@ func extractIntParam(q url.Values, key string, defaultValue int) (int, error) {
 	return v, nil
 }
 
+// censorPassword returns a string representation of the URL with the password replaced by "*****".
+func censorPassword(u *url.URL) string {
+	if password, hasPassword := u.User.Password(); hasPassword {
+		return strings.Replace(u.String(), ":"+password+"@", ":*****@", 1)
+	}
+	return u.String()
+}
+
 func extractDurationParam(q url.Values, key string, defaultValue time.Duration) (time.Duration, error) {
 	s := q.Get(key)
 	if s == "" {

db/pg/pg_test.go

@@ -0,0 +1,53 @@
+package pg
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestOpen_InvalidScheme(t *testing.T) {
+	_, err := Open("postgresql+psycopg2://user:pass@localhost/db")
+	require.Error(t, err)
+	require.Contains(t, err.Error(), `invalid database URL scheme "postgresql+psycopg2"`)
+	require.Contains(t, err.Error(), "*****")
+	require.NotContains(t, err.Error(), "pass")
+}
+
+func TestOpen_InvalidURL(t *testing.T) {
+	_, err := Open("not a valid url\x00")
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "invalid database URL")
+}
+
+func TestCensorPassword(t *testing.T) {
+	tests := []struct {
+		name     string
+		url      string
+		expected string
+	}{
+		{
+			name:     "with password",
+			url:      "postgres://user:secret@localhost/db",
+			expected: "postgres://user:*****@localhost/db",
+		},
+		{
+			name:     "without password",
+			url:      "postgres://localhost/db",
+			expected: "postgres://localhost/db",
+		},
+		{
+			name:     "user only",
+			url:      "postgres://user@localhost/db",
+			expected: "postgres://user@localhost/db",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			u, err := url.Parse(tt.url)
+			require.NoError(t, err)
+			require.Equal(t, tt.expected, censorPassword(u))
+		})
+	}
+}