Initial push

internal/dkr/data.go

@@ -0,0 +1,160 @@
+package dkr
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/arescom/docker-migrate/internal/spec"
+	dockertypes "github.com/docker/docker/api/types"
+	"github.com/docker/docker/api/types/container"
+	"github.com/docker/docker/api/types/image"
+)
+
+// CopyOut streams the contents of a path inside a container as an uncompressed
+// tar archive.
+//
+// This is the single mechanism used for every kind of data location. It works
+// for named volumes, anonymous volumes and bind mounts alike, because the
+// daemon resolves the mount and produces the tar itself: no helper image is
+// needed, the container's own image needs no tar binary, and the container does
+// not have to be running.
+//
+// The archive entries are rooted at the last path segment, matching `docker cp`
+// semantics. Restoring therefore targets the parent directory; use RestorePath.
+func (c *Client) CopyOut(ctx context.Context, containerID, srcPath string) (io.ReadCloser, error) {
+	rc, _, err := c.api.CopyFromContainer(ctx, containerID, srcPath)
+	if err != nil {
+		return nil, fmt.Errorf("read %s from %s: %w", srcPath, short(containerID), err)
+	}
+	return rc, nil
+}
+
+// CopyIn writes an uncompressed tar archive into a path inside a container.
+func (c *Client) CopyIn(ctx context.Context, containerID, dstPath string, r io.Reader) error {
+	err := c.api.CopyToContainer(ctx, containerID, dstPath, r, container.CopyToContainerOptions{
+		AllowOverwriteDirWithFile: false,
+		CopyUIDGID:                true,
+	})
+	if err != nil {
+		return fmt.Errorf("write %s into %s: %w", dstPath, short(containerID), err)
+	}
+	return nil
+}
+
+// RestorePath is the directory an archive produced by CopyOut must be extracted
+// into so that the contents land back at the original destination.
+func RestorePath(destination string) string {
+	d := path.Dir(strings.TrimSuffix(destination, "/"))
+	if d == "" || d == "." {
+		return "/"
+	}
+	return d
+}
+
+// SaveImage streams `docker save` output for one or more image references.
+func (c *Client) SaveImage(ctx context.Context, refs ...string) (io.ReadCloser, error) {
+	rc, err := c.api.ImageSave(ctx, refs)
+	if err != nil {
+		return nil, fmt.Errorf("save image %s: %w", strings.Join(refs, ","), err)
+	}
+	return rc, nil
+}
+
+// ImageSizeBytes returns the on-disk size of an image, used to estimate how
+// long a streamed transfer will take.
+func (c *Client) ImageSizeBytes(ctx context.Context, ref string) int64 {
+	insp, err := c.api.ImageInspect(ctx, ref)
+	if err != nil {
+		return -1
+	}
+	return insp.Size
+}
+
+// State returns the current status of a container, e.g. "running".
+func (c *Client) State(ctx context.Context, id string) (string, error) {
+	j, err := c.api.ContainerInspect(ctx, id)
+	if err != nil {
+		return "", err
+	}
+	if j.State == nil {
+		return "", errors.New("no state in inspect payload")
+	}
+	return j.State.Status, nil
+}
+
+// Stop stops a container and waits for it to settle. A container that is
+// already stopped is left alone.
+func (c *Client) Stop(ctx context.Context, id string, timeout time.Duration) error {
+	st, err := c.State(ctx, id)
+	if err != nil {
+		return err
+	}
+	if st != "running" && st != "restarting" && st != "paused" {
+		return nil
+	}
+	secs := int(timeout.Seconds())
+	if err := c.api.ContainerStop(ctx, id, container.StopOptions{Timeout: &secs}); err != nil {
+		return fmt.Errorf("stop %s: %w", short(id), err)
+	}
+	return nil
+}
+
+// Start starts a container.
+func (c *Client) Start(ctx context.Context, id string) error {
+	if err := c.api.ContainerStart(ctx, id, container.StartOptions{}); err != nil {
+		return fmt.Errorf("start %s: %w", short(id), err)
+	}
+	return nil
+}
+
+// VolumeSizes measures every local volume in one daemon round trip. It can be
+// slow on hosts with a lot of data, so the UI asks for it explicitly rather
+// than including it in the inventory.
+func (c *Client) VolumeSizes(ctx context.Context) (map[string]int64, error) {
+	du, err := c.api.DiskUsage(ctx, dockertypes.DiskUsageOptions{
+		Types: []dockertypes.DiskUsageObject{dockertypes.VolumeObject},
+	})
+	if err != nil {
+		return nil, fmt.Errorf("compute disk usage: %w", err)
+	}
+	out := map[string]int64{}
+	for _, v := range du.Volumes {
+		if v == nil || v.UsageData == nil {
+			continue
+		}
+		out[v.Name] = v.UsageData.Size
+	}
+	return out, nil
+}
+
+// MeasureMounts fills in the SizeBytes of every mount it can determine.
+// Volume sizes come from the daemon; bind mount sizes are measured by walking
+// the path from inside the container, which works even when the daemon is
+// remote.
+func (c *Client) MeasureMounts(ctx context.Context, containers []spec.Container) error {
+	sizes, err := c.VolumeSizes(ctx)
+	if err != nil {
+		return err
+	}
+	for i := range containers {
+		for j := range containers[i].Mounts {
+			m := &containers[i].Mounts[j]
+			switch m.Kind {
+			case spec.MountVolume, spec.MountAnonymous:
+				if s, ok := sizes[m.Name]; ok {
+					m.SizeBytes = s
+				}
+			case spec.MountTmpfs:
+				m.SizeBytes = 0
+			}
+		}
+	}
+	return nil
+}
+
+var _ = image.InspectResponse{}