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moby--moby/libcontainerd/remote/client_linux.go
Cory Snider 4bafaa00aa Refactor libcontainerd to minimize c8d RPCs
The containerd client is very chatty at the best of times. Because the
libcontained API is stateless and references containers and processes by
string ID for every method call, the implementation is essentially
forced to use the containerd client in a way which amplifies the number
of redundant RPCs invoked to perform any operation. The libcontainerd
remote implementation has to reload the containerd container, task
and/or process metadata for nearly every operation. This in turn
amplifies the number of context switches between dockerd and containerd
to perform any container operation or handle a containerd event,
increasing the load on the system which could otherwise be allocated to
workloads.

Overhaul the libcontainerd interface to reduce the impedance mismatch
with the containerd client so that the containerd client can be used
more efficiently. Split the API out into container, task and process
interfaces which the consumer is expected to retain so that
libcontainerd can retain state---especially the analogous containerd
client objects---without having to manage any state-store inside the
libcontainerd client.

Signed-off-by: Cory Snider <csnider@mirantis.com>
2022-08-24 14:59:08 -04:00

123 lines
3.4 KiB
Go

package remote // import "github.com/docker/docker/libcontainerd/remote"
import (
"context"
"fmt"
"os"
"path/filepath"
"strings"
"github.com/containerd/containerd"
"github.com/containerd/containerd/cio"
"github.com/containerd/containerd/containers"
libcontainerdtypes "github.com/docker/docker/libcontainerd/types"
"github.com/docker/docker/pkg/idtools"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/sirupsen/logrus"
)
func summaryFromInterface(i interface{}) (*libcontainerdtypes.Summary, error) {
return &libcontainerdtypes.Summary{}, nil
}
func (t *task) UpdateResources(ctx context.Context, resources *libcontainerdtypes.Resources) error {
// go doesn't like the alias in 1.8, this means this need to be
// platform specific
return t.Update(ctx, containerd.WithResources((*specs.LinuxResources)(resources)))
}
func hostIDFromMap(id uint32, mp []specs.LinuxIDMapping) int {
for _, m := range mp {
if id >= m.ContainerID && id <= m.ContainerID+m.Size-1 {
return int(m.HostID + id - m.ContainerID)
}
}
return 0
}
func getSpecUser(ociSpec *specs.Spec) (int, int) {
var (
uid int
gid int
)
for _, ns := range ociSpec.Linux.Namespaces {
if ns.Type == specs.UserNamespace {
uid = hostIDFromMap(0, ociSpec.Linux.UIDMappings)
gid = hostIDFromMap(0, ociSpec.Linux.GIDMappings)
break
}
}
return uid, gid
}
// WithBundle creates the bundle for the container
func WithBundle(bundleDir string, ociSpec *specs.Spec) containerd.NewContainerOpts {
return func(ctx context.Context, client *containerd.Client, c *containers.Container) error {
if c.Labels == nil {
c.Labels = make(map[string]string)
}
uid, gid := getSpecUser(ociSpec)
if uid == 0 && gid == 0 {
c.Labels[DockerContainerBundlePath] = bundleDir
return idtools.MkdirAllAndChownNew(bundleDir, 0755, idtools.Identity{UID: 0, GID: 0})
}
p := string(filepath.Separator)
components := strings.Split(bundleDir, string(filepath.Separator))
for _, d := range components[1:] {
p = filepath.Join(p, d)
fi, err := os.Stat(p)
if err != nil && !os.IsNotExist(err) {
return err
}
if os.IsNotExist(err) || fi.Mode()&1 == 0 {
p = fmt.Sprintf("%s.%d.%d", p, uid, gid)
if err := idtools.MkdirAndChown(p, 0700, idtools.Identity{UID: uid, GID: gid}); err != nil && !os.IsExist(err) {
return err
}
}
}
if c.Labels == nil {
c.Labels = make(map[string]string)
}
c.Labels[DockerContainerBundlePath] = p
return nil
}
}
func withLogLevel(_ logrus.Level) containerd.NewTaskOpts {
panic("Not implemented")
}
func newFIFOSet(bundleDir, processID string, withStdin, withTerminal bool) *cio.FIFOSet {
config := cio.Config{
Terminal: withTerminal,
Stdout: filepath.Join(bundleDir, processID+"-stdout"),
}
paths := []string{config.Stdout}
if withStdin {
config.Stdin = filepath.Join(bundleDir, processID+"-stdin")
paths = append(paths, config.Stdin)
}
if !withTerminal {
config.Stderr = filepath.Join(bundleDir, processID+"-stderr")
paths = append(paths, config.Stderr)
}
closer := func() error {
for _, path := range paths {
if err := os.RemoveAll(path); err != nil {
logrus.Warnf("libcontainerd: failed to remove fifo %v: %v", path, err)
}
}
return nil
}
return cio.NewFIFOSet(config, closer)
}
func (c *client) newDirectIO(ctx context.Context, fifos *cio.FIFOSet) (*cio.DirectIO, error) {
return cio.NewDirectIO(ctx, fifos)
}