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docker.go
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/
docker.go
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package layers
import (
"context"
"fmt"
"io"
"os"
"strings"
"time"
"github.com/containers/image/copy"
"github.com/containers/image/docker/daemon"
"github.com/containers/image/signature"
ctypes "github.com/containers/image/types"
"github.com/docker/distribution/reference"
"github.com/docker/docker/client"
"github.com/erikh/box/builder/config"
"github.com/erikh/box/fetcher"
"github.com/erikh/box/image"
"github.com/erikh/box/logger"
)
const megaByte = 1024 * 1024
// Docker needs a documetnation
type Docker struct {
context context.Context
tty bool
doSkipLayers bool
skipLayers []string
layers []string
images []string
client *client.Client
layerSet map[string]struct{}
logger *logger.Logger
}
// NewDocker needs a documetnation
func NewDocker(ctx context.Context, tty bool, logger *logger.Logger) (*Docker, error) {
client, err := client.NewEnvClient()
if err != nil {
return nil, err
}
return &Docker{
client: client,
context: ctx,
tty: tty,
logger: logger,
layerSet: map[string]struct{}{},
images: []string{},
skipLayers: []string{},
layers: []string{},
}, nil
}
// SetContext sets the context for subsequent calls.
func (d *Docker) SetContext(ctx context.Context) {
d.context = ctx
}
// AddImage adds layers to the layer list from a provided image, in order of
// appearance. Any existing layers are skipped over, removing them from the list.
func (d *Docker) AddImage(image string) error {
d.images = append(d.images, image)
resp, _, err := d.client.ImageInspectWithRaw(d.context, image)
if err != nil {
return err
}
for _, layer := range resp.RootFS.Layers {
if _, ok := d.layerSet[layer]; !ok {
if !d.doSkipLayers {
// XXX this really worries me. Pretty sure there's a potential cache
// fail/poison here, but I have to debug it.
// BETA QUALITY YO
d.layers = append(d.layers, layer)
} else {
// this is principally an optimization so we can determine later if we
// need to reconstruct the image.
d.skipLayers = append(d.skipLayers, layer)
}
d.layerSet[layer] = struct{}{}
}
}
return nil
}
// SetSkipLayers toggles whether or not to skip layers that are being built
// next. Toggle again to re-enable layer recording. The final image will not
// contain the skipped layers.
func (d *Docker) SetSkipLayers(ok bool) {
d.doSkipLayers = ok
}
func (d *Docker) uploadImage(fn string) (io.Reader, error) {
f, err := os.Open(fn)
if err != nil {
return nil, err
}
defer f.Close()
imgresp, err := d.client.ImageLoad(context.Background(), f, false)
if err != nil {
return nil, err
}
return imgresp.Body, nil
}
func (d *Docker) calculateCommits(layers []*image.Layer) []*image.Layer {
commitLayers := []*image.Layer{}
for i := 0; i < len(layers); i++ {
if i >= len(d.layers) {
break
}
commit := true
for layers[i].LayerID() != d.layers[i] {
if i == 0 {
layers = layers[1:]
} else {
layers = append(layers[:i-1], layers[i:]...)
}
if len(layers) < i || len(d.layers) < i {
commit = false
break
}
}
if commit {
commitLayers = append(commitLayers, layers[i])
}
}
return commitLayers
}
func (d *Docker) consumeEdits(progressChan chan ctypes.ProgressProperties) {
var last string
for prog := range progressChan {
if d.tty {
digest := prog.Artifact.Digest.String()
if digest == last {
fmt.Fprint(d.logger.Output(), "\r")
} else if last != "" {
fmt.Fprintln(d.logger.Output())
}
d.logger.Progress(strings.SplitN(digest, ":", 2)[1][:12], float64(prog.Offset/megaByte))
last = digest
}
}
if d.tty {
fmt.Fprintln(d.logger.Output())
}
}
func (d *Docker) makeImage(from string) (string, error) {
ref, err := daemon.ParseReference(from)
if err != nil {
return "", err
}
img, err := ref.NewImage(nil)
if err != nil {
return "", err
}
defer img.Close()
tgtRef, err := reference.ParseNamed(from)
if err != nil {
return "", err
}
tgt, err := daemon.NewReference("", tgtRef)
if err != nil {
return "", err
}
pc, err := signature.NewPolicyContext(&signature.Policy{
Default: []signature.PolicyRequirement{signature.NewPRInsecureAcceptAnything()},
})
if err != nil {
return "", err
}
progressChan := make(chan ctypes.ProgressProperties)
go d.consumeEdits(progressChan)
if d.tty {
d.logger.Print(d.logger.Notice("Editing image\n"))
} else {
d.logger.Print(d.logger.Notice("Editing image..."))
}
img2, err := copy.Image(pc, tgt, ref, ©.Options{
RemoveSignatures: true,
LayerCopyHook: func(srcLayer ctypes.BlobInfo) bool {
var found bool
for _, l := range d.layers {
if srcLayer.Digest.String() == l {
found = true
}
}
return found
},
Progress: progressChan,
ProgressInterval: 100 * time.Millisecond,
})
close(progressChan)
if err != nil {
return "", err
}
if !d.tty {
fmt.Fprintln(d.logger.Output(), "done.")
}
return img2.ConfigInfo().Digest.String(), nil
}
// MakeImage makes the final image, skipping any layers as necessary. The
// layers must be pre-recorded within the executor. Note that if you have no
// layers to skip, this operation will need to do nothing, so it will do
// nothing.
//
// It returns an error condition, if any.
func (d *Docker) MakeImage(config *config.Config) (string, error) {
// this is principally an optimization so we can determine later if we
// need to reconstruct the image.
if len(d.skipLayers) == 0 {
return config.Image, nil
}
var err error
config.Image, err = d.makeImage(config.Image)
if err != nil {
return "", err
}
return config.Image, nil
}
// Lookup an image by name, returning the id.
func (d *Docker) Lookup(name string) (string, error) {
img, _, err := d.client.ImageInspectWithRaw(d.context, name)
if err != nil {
return "", err
}
return img.ID, nil
}
// Fetch retrieves a docker image, overwrites the container configuration, and
// returns its id.
func (d *Docker) Fetch(config *config.Config, name string) (string, error) {
location, layers, err := fetcher.Docker(d.context, d.logger, d.client, d.tty, config, name)
if err != nil {
return "", err
}
d.SetLayers(layers)
return location, nil
}
// SetLayers sets the layers.
func (d *Docker) SetLayers(layers []string) {
d.layers = layers
}