feat(cli): show storage capacity in repo status (#1867)

The connected repository's backing storage capacity and available
space can be now retrieved from `kopia repository status`. In text
format, these fields are printed in a human friendly form (MiB, GiB).
In JSON mode (`--json`), they are output as bytes.

Co-authored-by: Shikhar Mall <mall.shikhar.in@gmail.com>
Co-authored-by: Julio

cli/command_repository_status.go

@@ -34,6 +34,7 @@ type RepositoryStatus struct {
 
 	ClientOptions repo.ClientOptions        `json:"clientOptions"`
 	Storage       blob.ConnectionInfo       `json:"storage"`
+	Capacity      *blob.Capacity            `json:"volume,omitempty"`
 	ContentFormat content.FormattingOptions `json:"contentFormat"`
 	ObjectFormat  object.Format             `json:"objectFormat"`
 	BlobRetention content.BlobCfgBlob       `json:"blobRetention"`
@@ -50,7 +51,7 @@ func (c *commandRepositoryStatus) setup(svc advancedAppServices, parent commandP
 	c.jo.setup(svc, cmd)
 }
 
-func (c *commandRepositoryStatus) outputJSON(r repo.Repository) error {
+func (c *commandRepositoryStatus) outputJSON(ctx context.Context, r repo.Repository) error {
 	s := RepositoryStatus{
 		ConfigFile:    c.svc.repositoryConfigFileName(),
 		ClientOptions: r.ClientOptions(),
@@ -64,6 +65,15 @@ func (c *commandRepositoryStatus) outputJSON(r repo.Repository) error {
 		s.BlobRetention = dr.BlobCfg()
 		s.Storage = scrubber.ScrubSensitiveData(reflect.ValueOf(ci)).Interface().(blob.ConnectionInfo)                                             // nolint:forcetypeassert
 		s.ContentFormat = scrubber.ScrubSensitiveData(reflect.ValueOf(dr.ContentReader().ContentFormat())).Interface().(content.FormattingOptions) // nolint:forcetypeassert
+
+		switch cp, err := dr.BlobVolume().GetCapacity(ctx); {
+		case err == nil:
+			s.Capacity = &cp
+		case errors.Is(err, blob.ErrNotAVolume):
+			// This is okay, we will just not populate the result.
+		default:
+			return errors.Wrap(err, "unable to get storage volume capacity")
+		}
 	}
 
 	c.out.printStdout("%s\n", c.jo.jsonBytes(s))
@@ -71,9 +81,10 @@ func (c *commandRepositoryStatus) outputJSON(r repo.Repository) error {
 	return nil
 }
 
+// nolint: funlen
 func (c *commandRepositoryStatus) run(ctx context.Context, rep repo.Repository) error {
 	if c.jo.jsonOutput {
-		return c.outputJSON(rep)
+		return c.outputJSON(ctx, rep)
 	}
 
 	c.out.printStdout("Config file:         %v\n", c.svc.repositoryConfigFileName())
@@ -99,6 +110,16 @@ func (c *commandRepositoryStatus) run(ctx context.Context, rep repo.Repository)
 	ci := dr.BlobReader().ConnectionInfo()
 	c.out.printStdout("Storage type:        %v\n", ci.Type)
 
+	switch cp, err := dr.BlobVolume().GetCapacity(ctx); {
+	case err == nil:
+		c.out.printStdout("Storage capacity:    %v\n", units.BytesStringBase10(int64(cp.SizeB)))
+		c.out.printStdout("Storage available:   %v\n", units.BytesStringBase10(int64(cp.FreeB)))
+	case errors.Is(err, blob.ErrNotAVolume):
+		c.out.printStdout("Storage capacity:    unbounded\n")
+	default:
+		return errors.Wrap(err, "unable to get storage volume capacity")
+	}
+
 	if cjson, err := json.MarshalIndent(scrubber.ScrubSensitiveData(reflect.ValueOf(ci.Config)).Interface(), "                     ", "  "); err == nil {
 		c.out.printStdout("Storage config:      %v\n", string(cjson))
 	}

repo/blob/storage.go

@@ -56,9 +56,9 @@ type OutputBuffer interface {
 // Capacity describes the storage capacity and usage of a Volume.
 type Capacity struct {
 	// Size of volume in bytes.
-	SizeB uint64
+	SizeB uint64 `json:"capacity,omitempty"`
 	// Available (writeable) space in bytes.
-	FreeB uint64
+	FreeB uint64 `json:"available"`
 }
 
 // Volume defines disk/volume access API to blob storage.

repo/repository.go

@@ -50,6 +50,7 @@ type DirectRepository interface {
 	ObjectFormat() object.Format
 	BlobCfg() content.BlobCfgBlob
 	BlobReader() blob.Reader
+	BlobVolume() blob.Volume
 	ContentReader() content.Reader
 	IndexBlobs(ctx context.Context, includeInactive bool) ([]content.IndexBlobInfo, error)
 	Crypter() *content.Crypter
@@ -308,6 +309,11 @@ func (r *directRepository) BlobReader() blob.Reader {
 	return r.blobs
 }
 
+// BlobVolume returns the blob volume interface.
+func (r *directRepository) BlobVolume() blob.Volume {
+	return r.blobs
+}
+
 // ContentReader returns the content reader.
 func (r *directRepository) ContentReader() content.Reader {
 	return r.cmgr