pulumi/pulumi · error

running pager: %w

Error message

running pager: %w

What it means

The no-op pager's runNoopPager copies the command output through an io.Pipe to stdout. If the copy fails mid-stream (e.g. the writing goroutine's function errored and closed the pipe writer, or stdout became unwritable), the error is wrapped as "running pager: %w". Despite the message, this is in the fallback (non-pager) path.

Source

Thrown at pkg/cmd/esc/cli/pager/noop.go:39

)

func runNoopPager(stdout io.Writer, f func(context.Context, io.Writer) error) error {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	r, stdin := io.Pipe()
	defer r.Close()

	done := make(chan error)
	go func() {
		done <- func() error {
			defer stdin.Close()
			return f(ctx, stdin)
		}()
	}()

	if _, err := io.Copy(stdout, r); err != nil {
		return fmt.Errorf("running pager: %w", err)
	}
	cancel()

	return <-done
}

View on GitHub (pinned to 793f7b2e16)

Solutions

1. Check the wrapped cause: an EPIPE usually means the downstream consumer (head, grep -q) closed early — handle SIGPIPE or avoid closing early
2. Retry the command writing directly to a file instead of a pipe
3. Capture output to a file (`> out.json`) to rule out pipe issues
4. If the producer function failed, inspect its error for the root cause

// prefer capturing to a file to avoid pipe failures
esc env get my-env --output json > out.json

out, err := exec.Command("esc", "env", "get", "my-env").Output()
if err != nil {
	var ee *exec.ExitError
	if errors.As(err, &ee) && isBrokenPipe(ee) {
		// downstream consumer (head, grep -q) closed the pipe: treat as benign
		return nil
	}
	return err
}

When it happens

Trigger: Output is written through the pipe while the producer function f(ctx, stdin) fails and closes the writer prematurely, or io.Copy fails writing to stdout (broken pipe, e.g. `esc ... | head` closing downstream, or a full/closed stdout).

Common situations: Piping ESC CLI output into `head` or a command that exits early, causing EPIPE on stdout; downstream consumer crashes while the CLI is streaming JSON output.

Related errors

• reading environment definition: %w
• could not read from stdin: %w
• running pager: %w
• reading role details from stdin: %w
• reading role details from %q: %w

AI-assisted analysis of pulumi/pulumi@793f7b2e16 (2026-08-31). Data as JSON: /api/errors/f5a062c1d1f726bf. Report an issue: GitHub.