Add errgo as a dep, and start using it.

state/apiserver/client/client.go

Index: state/apiserver/client/client.go 
=== modified file 'state/apiserver/client/client.go' 
--- state/apiserver/client/client.go	2014-01-30 14:22:46 +0000 
+++ state/apiserver/client/client.go	2014-02-03 14:31:54 +0000 
@@ -9,6 +9,7 @@ 
	"os" 
	"strings" 
 
+	"github.com/errgo/errgo" 
	"github.com/loggo/loggo" 
 
	"launchpad.net/juju-core/charm" 
@@ -851,47 +852,47 @@ 
	store := config.AuthorizeCharmRepo(CharmStore, envConfig) 
	downloadedCharm, err := store.Get(charmURL) 
	if err != nil { 
-	return fmt.Errorf("cannot download charm %q: %v", charmURL.String(), err) 
+	return errgo.Annotatef(err, "cannot download charm %q", charmURL.String()) 
	} 
 
	// Open it and calculate the SHA256 hash. 
	downloadedBundle, ok := downloadedCharm.(*charm.Bundle) 
	if !ok { 
-	return fmt.Errorf("expected a charm archive, got %T", downloadedCharm) 
+	return errgo.New("expected a charm archive, got %T", downloadedCharm) 
	} 
	archive, err := os.Open(downloadedBundle.Path) 
	if err != nil { 
-	return fmt.Errorf("cannot read downloaded charm: %v", err) 
+	return errgo.Annotate(err, "cannot read downloaded charm") 
	} 
	defer archive.Close() 
	bundleSHA256, size, err := utils.ReadSHA256(archive) 
	if err != nil { 
-	return fmt.Errorf("cannot calculate SHA256 hash of charm: %v", err) 
+	return errgo.Annotate(err, "cannot calculate SHA256 hash of charm") 
	} 
	if _, err := archive.Seek(0, 0); err != nil { 
-	return fmt.Errorf("cannot rewind charm archive: %v", err) 
+	return errgo.Annotate(err, "cannot rewind charm archive") 
	} 
 
	// Get the environment storage and upload the charm. 
	env, err := environs.New(envConfig) 
	if err != nil { 
-	return fmt.Errorf("cannot access environment: %v", err) 
+	return errgo.Annotate(err, "cannot access environment") 
	} 
	storage := env.Storage() 
	archiveName, err := CharmArchiveName(charmURL.Name, charmURL.Revision) 
	if err != nil { 
-	return fmt.Errorf("cannot generate charm archive name: %v", err) 
+	return errgo.Annotate(err, "cannot generate charm archive name") 
	} 
	if err := storage.Put(archiveName, archive, size); err != nil { 
-	return fmt.Errorf("cannot upload charm to provider storage: %v", err) 
+	return errgo.Annotate(err, "cannot upload charm to provider storage") 
	} 
	storageURL, err := storage.URL(archiveName) 
	if err != nil { 
-	return fmt.Errorf("cannot get storage URL for charm: %v", err) 
+	return errgo.Annotate(err, "cannot get storage URL for charm") 
	} 
	bundleURL, err := url.Parse(storageURL) 
	if err != nil { 
-	return fmt.Errorf("cannot parse storage URL: %v", err) 
+	return errgo.Annotate(err, "cannot parse storage URL") 
	} 
 
	// Finally, update the charm data in state and mark it as no longer pending. 
@@ -903,7 +904,7 @@ 
	// us. This means we have to delete what we just uploaded 
	// to storage. 
	if err := storage.Remove(archiveName); err != nil { 
-	logger.Errorf("cannot remove duplicated charm from storage: %v", err) 
+	errgo.Annotate(err, "cannot remove duplicated charm from storage") 
	} 
	return nil 
	}