From 3bfc82257878e55141bb029390574130c3ac0530 Mon Sep 17 00:00:00 2001
From: "Guillaume J. Charmes" <guillaume@dotcloud.com>
Date: Mon, 17 Jun 2013 18:39:30 -0700
Subject: [PATCH] * API: Add tag lookup to history command. Fixes #882

---
 api_params.go |  1 +
 commands.go   |  2 +-
 server.go     | 14 ++++++++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/api_params.go b/api_params.go
index 2a641f8ccd..c3fabb2be0 100644
--- a/api_params.go
+++ b/api_params.go
@@ -2,6 +2,7 @@ package docker
 
 type APIHistory struct {
 	ID        string `json:"Id"`
+	Tag       string `json:",omitempty"`
 	Created   int64
 	CreatedBy string `json:",omitempty"`
 }
diff --git a/commands.go b/commands.go
index ce15fd6cf1..98be40181c 100644
--- a/commands.go
+++ b/commands.go
@@ -627,7 +627,7 @@ func (cli *DockerCli) CmdHistory(args ...string) error {
 	fmt.Fprintln(w, "ID\tCREATED\tCREATED BY")
 
 	for _, out := range outs {
-		fmt.Fprintf(w, "%s\t%s ago\t%s\n", out.ID, utils.HumanDuration(time.Now().Sub(time.Unix(out.Created, 0))), out.CreatedBy)
+		fmt.Fprintf(w, "%s (%s)\t%s ago\t%s\n", out.ID, out.Tag, utils.HumanDuration(time.Now().Sub(time.Unix(out.Created, 0))), out.CreatedBy)
 	}
 	w.Flush()
 	return nil
diff --git a/server.go b/server.go
index 30e3ec6b3a..912349b82e 100644
--- a/server.go
+++ b/server.go
@@ -218,12 +218,26 @@ func (srv *Server) ImageHistory(name string) ([]APIHistory, error) {
 		return nil, err
 	}
 
+	lookupMap := make(map[string]string)
+	for name, repository := range srv.runtime.repositories.Repositories {
+		for tag, id := range repository {
+			// If the ID already has a reverse lookup, do not update it unless for "latest"
+			if _, exists := lookupMap[id]; exists {
+				if tag != "latest" {
+					continue
+				}
+			}
+			lookupMap[id] = name + ":" + tag
+		}
+	}
+
 	outs := []APIHistory{} //produce [] when empty instead of 'null'
 	err = image.WalkHistory(func(img *Image) error {
 		var out APIHistory
 		out.ID = srv.runtime.repositories.ImageName(img.ShortID())
 		out.Created = img.Created.Unix()
 		out.CreatedBy = strings.Join(img.ContainerConfig.Cmd, " ")
+		out.Tag = lookupMap[img.ID]
 		outs = append(outs, out)
 		return nil
 	})