Merge pull request #7604 from vrothberg/fix-7406

system df: fix image-size calculations

1 files changed, 126 insertions, 0 deletions

diff --git a/libpod/image/df.go b/libpod/image/df.go
new file mode 100644
index 000000000..84cf7af9e
--- /dev/null
+++ b/libpod/image/df.go
@@ -0,0 +1,126 @@
+package image
+
+import (
+	"context"
+	"time"
+
+	"github.com/containers/image/v5/docker/reference"
+)
+
+// DiskUsageStat gives disk-usage statistics for a specific image.
+type DiskUsageStat struct {
+	// ID of the image.
+	ID string
+	// Repository of the first recorded name of the image.
+	Repository string
+	// Tag of the first recorded name of the image.
+	Tag string
+	// Created is the creation time of the image.
+	Created time.Time
+	// SharedSize is the amount of space shared with another image.
+	SharedSize uint64
+	// UniqueSize is the amount of space used only by this image.
+	UniqueSize uint64
+	// Size is the total size of the image (i.e., the sum of the shared and
+	// unique size).
+	Size uint64
+	// Number of containers using the image.
+	Containers int
+}
+
+// DiskUsage returns disk-usage statistics for the specified slice of images.
+func (ir *Runtime) DiskUsage(ctx context.Context, images []*Image) ([]DiskUsageStat, error) {
+	stats := make([]DiskUsageStat, len(images))
+
+	// Build a layerTree to quickly compute (and cache!) parent/child
+	// relations.
+	tree, err := ir.layerTree()
+	if err != nil {
+		return nil, err
+	}
+
+	// Calculate the stats for each image.
+	for i, img := range images {
+		stat, err := diskUsageForImage(ctx, img, tree)
+		if err != nil {
+			return nil, err
+		}
+		stats[i] = *stat
+	}
+
+	return stats, nil
+}
+
+// diskUsageForImage returns the disk-usage statistics for the spcified image.
+func diskUsageForImage(ctx context.Context, image *Image, tree *layerTree) (*DiskUsageStat, error) {
+	stat := DiskUsageStat{
+		ID:      image.ID(),
+		Created: image.Created(),
+	}
+
+	// Repository and tag.
+	var name, repository, tag string
+	for _, n := range image.Names() {
+		if len(n) > 0 {
+			name = n
+			break
+		}
+	}
+	if len(name) > 0 {
+		named, err := reference.ParseNormalizedNamed(name)
+		if err != nil {
+			return nil, err
+		}
+		repository = named.Name()
+		if tagged, isTagged := named.(reference.NamedTagged); isTagged {
+			tag = tagged.Tag()
+		}
+	} else {
+		repository = "<none>"
+		tag = "<none>"
+	}
+	stat.Repository = repository
+	stat.Tag = tag
+
+	// Shared, unique and total size.
+	parent, err := tree.parent(ctx, image)
+	if err != nil {
+		return nil, err
+	}
+	childIDs, err := tree.children(ctx, image, false)
+	if err != nil {
+		return nil, err
+	}
+	// Optimistically set unique size to the full size of the image.
+	size, err := image.Size(ctx)
+	if err != nil {
+		return nil, err
+	}
+	stat.UniqueSize = *size
+
+	if len(childIDs) > 0 {
+		// If we have children, we share everything.
+		stat.SharedSize = stat.UniqueSize
+		stat.UniqueSize = 0
+	} else if parent != nil {
+		// If we have no children but a parent, remove the parent
+		// (shared) size from the unique one.
+		size, err := parent.Size(ctx)
+		if err != nil {
+			return nil, err
+		}
+		stat.UniqueSize -= *size
+		stat.SharedSize = *size
+	}
+
+	stat.Size = stat.SharedSize + stat.UniqueSize
+
+	// Number of containers using the image.
+	containers, err := image.Containers()
+	if err != nil {
+		return nil, err
+	}
+	stat.Containers = len(containers)
+
+	return &stat, nil
+}