package cmd

import (
	"fmt"
	"io"
	"os"
)

// newWarnWriter forwards everything written to it to stderr, prefixed
// with a tag. Used to surface docker subcommand stderr in CI logs.
func newWarnWriter(tag string) io.Writer {
	return &warnWriter{tag: tag}
}

type warnWriter struct{ tag string }

func (w *warnWriter) Write(p []byte) (int, error) {
	fmt.Fprintf(os.Stderr, "[%s] %s", w.tag, p)
	return len(p), nil
}