ioprogress is a Go (golang) library with implementations of io.Reader
and io.Writer that draws progress bars. The primary use case for these
are for CLI applications but alternate progress bar writers can be supplied
for alternate environments.
Standard go get:
$ go get github.com/mitchellh/ioprogress
Here is an example of outputting a basic progress bar to the CLI as
we're "downloading" from some other io.Reader (perhaps from a network
connection):
// Imagine this came from some external source, such as a network connection,
// and that we have the full size of it, such as from a Content-Length HTTP
// header.
var r io.Reader
// Create the progress reader
progressR := &ioprogress.Reader{
Reader: r,
Size: rSize,
}
// Copy all of the reader to some local file f. As it copies, the
// progressR will write progress to the terminal on os.Stdout. This is
// customizable.
io.Copy(f, progressR)