From 003ec21d360b08d50b61834795692542fff295e2 Mon Sep 17 00:00:00 2001
From: Solomon Hykes <solomon@dotcloud.com>
Date: Tue, 26 Feb 2013 17:28:24 -0800
Subject: [PATCH] If curl is installed, 'docker pull' will use it to download
 images with a pretty progress bar. Otherwise it will fallback to regular
 http.Get()

---
 README.md        |  2 +-
 future/future.go | 17 +++++++++++++++++
 server/server.go | 12 +++++++++---
 3 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index cf3f74dc61..aea3d10e9d 100644
--- a/README.md
+++ b/README.md
@@ -157,7 +157,7 @@ Step by step host setup
 3. Type the following commands:
 
         apt-get update
-        apt-get install lxc wget bsdtar
+        apt-get install lxc wget bsdtar curl
 
 4. Download the latest version of the [docker binaries](https://dl.dropbox.com/u/20637798/docker.tar.gz) (`wget https://dl.dropbox.com/u/20637798/docker.tar.gz`) (warning: this may not be the most up-to-date build)
 5. Extract the contents of the tar file `tar -xf docker.tar.gz`
diff --git a/future/future.go b/future/future.go
index 75caab3d19..33f1f8925c 100644
--- a/future/future.go
+++ b/future/future.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"math/rand"
+	"os/exec"
 	"time"
 )
 
@@ -83,3 +84,19 @@ func Pv(src io.Reader, info io.Writer) io.Reader {
 	}()
 	return r
 }
+
+// Curl makes an http request by executing the unix command 'curl', and returns
+// the body of the response. If `stderr` is not nil, a progress bar will be
+// written to it.
+func Curl(url string, stderr io.Writer) (io.Reader, error) {
+	curl := exec.Command("curl", "-#", "-L", url)
+	output, err := curl.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	curl.Stderr = stderr
+	if err := curl.Start(); err != nil {
+		return nil, err
+	}
+	return output, nil
+}
diff --git a/server/server.go b/server/server.go
index ee2c997634..2ef42f8b16 100644
--- a/server/server.go
+++ b/server/server.go
@@ -390,12 +390,18 @@ func (srv *Server) CmdPull(stdin io.ReadCloser, stdout io.Writer, args ...string
 		u.Path = path.Join("/docker.io/images", u.Path)
 	}
 	fmt.Fprintf(stdout, "Downloading from %s\n", u.String())
-	resp, err := http.Get(u.String())
+	// Download with curl (pretty progress bar)
+	// If curl is not available, fallback to http.Get()
+	archive, err := future.Curl(u.String(), stdout)
 	if err != nil {
-		return err
+		if resp, err := http.Get(u.String()); err != nil {
+			return err
+		} else {
+			archive = resp.Body
+		}
 	}
 	fmt.Fprintf(stdout, "Unpacking to %s\n", name)
-	img, err := srv.images.Import(name, resp.Body, nil)
+	img, err := srv.images.Import(name, archive, nil)
 	if err != nil {
 		return err
 	}