Fix tools metadata generation for null provider

cmd/plugins/juju-metadata/toolsmetadata.go

 // Copyright 2013 Canonical Ltd.
 // Licensed under the AGPLv3, see LICENCE file for details.
 
 package main
 
 import (
         "fmt"
 
         "launchpad.net/gnuflag"
         "launchpad.net/loggo"
 
         "launchpad.net/juju-core/cmd"
         "launchpad.net/juju-core/environs/config"
         "launchpad.net/juju-core/environs/filestorage"
+        "launchpad.net/juju-core/environs/storage"
         "launchpad.net/juju-core/environs/sync"
         "launchpad.net/juju-core/environs/tools"
         "launchpad.net/juju-core/provider/ec2/httpstorage"
+        coretools "launchpad.net/juju-core/tools"
         "launchpad.net/juju-core/utils"
         "launchpad.net/juju-core/version"
 )
 
 var DefaultToolsLocation = sync.DefaultToolsLocation
 
 // ToolsMetadataCommand is used to generate simplestreams metadata for
 // juju tools.
 type ToolsMetadataCommand struct {
         cmd.EnvCommandBase
         fetch       bool
         metadataDir string
 
         // noS3 is used in testing to disable the use of S3 public storage
         // as a backup.
         noS3 bool
 }
 
 func (c *ToolsMetadataCommand) Info() *cmd.Info {
         return &cmd.Info{
                 Name:    "generate-tools",
                 Purpose: "generate simplestreams tools metadata",
         }
 }
 
 func (c *ToolsMetadataCommand) SetFlags(f *gnuflag.FlagSet) {
         c.EnvCommandBase.SetFlags(f)
-        f.BoolVar(&c.fetch, "fetch", true, "fetch tools and compute content size and hash")
         f.StringVar(&c.metadataDir, "d", "", "local directory in which to store metadata")
 }
 
 func (c *ToolsMetadataCommand) Run(context *cmd.Context) error {
         loggo.RegisterWriter("toolsmetadata", cmd.NewCommandLogWriter("juju.environs.tools", context.Stdout, context.Stderr), loggo.INFO)
         defer loggo.RemoveWriter("toolsmetadata")
         if c.metadataDir == "" {
                 c.metadataDir = config.JujuHome()
         }
         c.metadataDir = utils.NormalizePath(c.metadataDir)
@@ skipping 10 matching lines @@
                 toolsList, err = tools.ReadList(sourceStorage, version.Current.Major, minorVersion)
         }
         if err != nil {
                 return err
         }
 
         targetStorage, err := filestorage.NewFileStorageWriter(c.metadataDir, filestorage.UseDefaultTmpDir)
         if err != nil {
                 return err
         }
-        return tools.MergeAndWriteMetadata(targetStorage, toolsList, c.fetch)
+        return mergeAndWriteMetadata(targetStorage, toolsList)
 }
+
+// This is essentially the same as tools.MergeAndWriteMetadata, but also
+// resolves metadata for existing tools by fetching them and computing
+// size/sha256 locally.
+func mergeAndWriteMetadata(stor storage.Storage, toolsList coretools.List) error {
+        existing, err := tools.ReadMetadata(stor)
+        if err != nil {
+                return err
+        }
+        metadata := tools.MetadataFromTools(toolsList)
+        if metadata, err = tools.MergeMetadata(metadata, existing); err != nil {
+                return err
+        }
+        if err = tools.ResolveMetadata(stor, metadata); err != nil {
+                return err
+        }
+        return tools.WriteMetadata(stor, metadata)
+}