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container_operations_unix.go
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container_operations_unix.go
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//go:build linux || freebsd
// +build linux freebsd
package daemon // import "github.com/docker/docker/daemon"
import (
"fmt"
"os"
"strconv"
"github.com/docker/docker/container"
"github.com/docker/docker/daemon/links"
"github.com/docker/docker/errdefs"
"github.com/docker/docker/pkg/idtools"
"github.com/docker/docker/pkg/stringid"
"github.com/docker/docker/pkg/system"
"github.com/docker/docker/runconfig"
"github.com/docker/libnetwork"
"github.com/opencontainers/selinux/go-selinux/label"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
func (daemon *Daemon) setupLinkedContainers(container *container.Container) ([]string, error) {
var env []string
children := daemon.children(container)
bridgeSettings := container.NetworkSettings.Networks[runconfig.DefaultDaemonNetworkMode().NetworkName()]
if bridgeSettings == nil || bridgeSettings.EndpointSettings == nil {
return nil, nil
}
for linkAlias, child := range children {
if !child.IsRunning() {
return nil, fmt.Errorf("Cannot link to a non running container: %s AS %s", child.Name, linkAlias)
}
childBridgeSettings := child.NetworkSettings.Networks[runconfig.DefaultDaemonNetworkMode().NetworkName()]
if childBridgeSettings == nil || childBridgeSettings.EndpointSettings == nil {
return nil, fmt.Errorf("container %s not attached to default bridge network", child.ID)
}
link := links.NewLink(
bridgeSettings.IPAddress,
childBridgeSettings.IPAddress,
linkAlias,
child.Config.Env,
child.Config.ExposedPorts,
)
env = append(env, link.ToEnv()...)
}
return env, nil
}
func (daemon *Daemon) getIpcContainer(id string) (*container.Container, error) {
errMsg := "can't join IPC of container " + id
// Check the container exists
ctr, err := daemon.GetContainer(id)
if err != nil {
return nil, errors.Wrap(err, errMsg)
}
// Check the container is running and not restarting
if err := daemon.checkContainer(ctr, containerIsRunning, containerIsNotRestarting); err != nil {
return nil, errors.Wrap(err, errMsg)
}
// Check the container ipc is shareable
if st, err := os.Stat(ctr.ShmPath); err != nil || !st.IsDir() {
if err == nil || os.IsNotExist(err) {
return nil, errors.New(errMsg + ": non-shareable IPC (hint: use IpcMode:shareable for the donor container)")
}
// stat() failed?
return nil, errors.Wrap(err, errMsg+": unexpected error from stat "+ctr.ShmPath)
}
return ctr, nil
}
func (daemon *Daemon) getPidContainer(ctr *container.Container) (*container.Container, error) {
containerID := ctr.HostConfig.PidMode.Container()
ctr, err := daemon.GetContainer(containerID)
if err != nil {
return nil, errors.Wrapf(err, "cannot join PID of a non running container: %s", containerID)
}
return ctr, daemon.checkContainer(ctr, containerIsRunning, containerIsNotRestarting)
}
func containerIsRunning(c *container.Container) error {
if !c.IsRunning() {
return errdefs.Conflict(errors.Errorf("container %s is not running", c.ID))
}
return nil
}
func containerIsNotRestarting(c *container.Container) error {
if c.IsRestarting() {
return errContainerIsRestarting(c.ID)
}
return nil
}
func (daemon *Daemon) setupIpcDirs(c *container.Container) error {
ipcMode := c.HostConfig.IpcMode
switch {
case ipcMode.IsContainer():
ic, err := daemon.getIpcContainer(ipcMode.Container())
if err != nil {
return err
}
c.ShmPath = ic.ShmPath
case ipcMode.IsHost():
if _, err := os.Stat("/dev/shm"); err != nil {
return fmt.Errorf("/dev/shm is not mounted, but must be for --ipc=host")
}
c.ShmPath = "/dev/shm"
case ipcMode.IsPrivate(), ipcMode.IsNone():
// c.ShmPath will/should not be used, so make it empty.
// Container's /dev/shm mount comes from OCI spec.
c.ShmPath = ""
case ipcMode.IsEmpty():
// A container was created by an older version of the daemon.
// The default behavior used to be what is now called "shareable".
fallthrough
case ipcMode.IsShareable():
rootIDs := daemon.idMapping.RootPair()
if !c.HasMountFor("/dev/shm") {
shmPath, err := c.ShmResourcePath()
if err != nil {
return err
}
if err := idtools.MkdirAllAndChown(shmPath, 0700, rootIDs); err != nil {
return err
}
shmproperty := "mode=1777,size=" + strconv.FormatInt(c.HostConfig.ShmSize, 10)
if err := unix.Mount("shm", shmPath, "tmpfs", uintptr(unix.MS_NOEXEC|unix.MS_NOSUID|unix.MS_NODEV), label.FormatMountLabel(shmproperty, c.GetMountLabel())); err != nil {
return fmt.Errorf("mounting shm tmpfs: %s", err)
}
if err := os.Chown(shmPath, rootIDs.UID, rootIDs.GID); err != nil {
return err
}
c.ShmPath = shmPath
}
default:
return fmt.Errorf("invalid IPC mode: %v", ipcMode)
}
return nil
}
func (daemon *Daemon) setupSecretDir(c *container.Container) (setupErr error) {
if len(c.SecretReferences) == 0 && len(c.ConfigReferences) == 0 {
return nil
}
return fmt.Errorf("secret store is not initialized")
}
func (daemon *Daemon) cleanupSecretDir(c *container.Container) {
// noop
}
func killProcessDirectly(container *container.Container) error {
pid := container.GetPID()
// Ensure that we don't kill ourselves
if pid == 0 {
return nil
}
if err := unix.Kill(pid, 9); err != nil {
if err != unix.ESRCH {
return err
}
e := errNoSuchProcess{pid, 9}
logrus.WithError(e).WithField("container", container.ID).Debug("no such process")
return e
}
// In case there were some exceptions(e.g., state of zombie and D)
if system.IsProcessAlive(pid) {
// Since we can not kill a zombie pid, add zombie check here
isZombie, err := system.IsProcessZombie(pid)
if err != nil {
logrus.WithError(err).WithField("container", container.ID).Warn("Container state is invalid")
return err
}
if isZombie {
return errdefs.System(errors.Errorf("container %s PID %d is zombie and can not be killed. Use the --init option when creating containers to run an init inside the container that forwards signals and reaps processes", stringid.TruncateID(container.ID), pid))
}
}
return nil
}
func isLinkable(child *container.Container) bool {
// A container is linkable only if it belongs to the default network
_, ok := child.NetworkSettings.Networks[runconfig.DefaultDaemonNetworkMode().NetworkName()]
return ok
}
func enableIPOnPredefinedNetwork() bool {
return false
}
// serviceDiscoveryOnDefaultNetwork indicates if service discovery is supported on the default network
func serviceDiscoveryOnDefaultNetwork() bool {
return false
}
func (daemon *Daemon) setupPathsAndSandboxOptions(container *container.Container, sboxOptions *[]libnetwork.SandboxOption) error {
var err error
// Set the correct paths for /etc/hosts and /etc/resolv.conf, based on the
// networking-mode of the container. Note that containers with "container"
// networking are already handled in "initializeNetworking()" before we reach
// this function, so do not have to be accounted for here.
switch {
case container.HostConfig.NetworkMode.IsHost():
// In host-mode networking, the container does not have its own networking
// namespace, so both `/etc/hosts` and `/etc/resolv.conf` should be the same
// as on the host itself. The container gets a copy of these files.
*sboxOptions = append(
*sboxOptions,
libnetwork.OptionOriginHostsPath("/etc/hosts"),
libnetwork.OptionOriginResolvConfPath("/etc/resolv.conf"),
)
case container.HostConfig.NetworkMode.IsUserDefined():
// The container uses a user-defined network. We use the embedded DNS
// server for container name resolution and to act as a DNS forwarder
// for external DNS resolution.
// We parse the DNS server(s) that are defined in /etc/resolv.conf on
// the host, which may be a local DNS server (for example, if DNSMasq or
// systemd-resolvd are in use). The embedded DNS server forwards DNS
// resolution to the DNS server configured on the host, which in itself
// may act as a forwarder for external DNS servers.
// If systemd-resolvd is used, the "upstream" DNS servers can be found in
// /run/systemd/resolve/resolv.conf. We do not query those DNS servers
// directly, as they can be dynamically reconfigured.
*sboxOptions = append(
*sboxOptions,
libnetwork.OptionOriginResolvConfPath("/etc/resolv.conf"),
)
default:
// For other situations, such as the default bridge network, container
// discovery / name resolution is handled through /etc/hosts, and no
// embedded DNS server is available. Without the embedded DNS, we
// cannot use local DNS servers on the host (for example, if DNSMasq or
// systemd-resolvd is used). If systemd-resolvd is used, we try to
// determine the external DNS servers that are used on the host.
// This situation is not ideal, because DNS servers configured in the
// container are not updated after the container is created, but the
// DNS servers on the host can be dynamically updated.
//
// Copy the host's resolv.conf for the container (/run/systemd/resolve/resolv.conf or /etc/resolv.conf)
*sboxOptions = append(
*sboxOptions,
libnetwork.OptionOriginResolvConfPath(daemon.configStore.GetResolvConf()),
)
}
container.HostsPath, err = container.GetRootResourcePath("hosts")
if err != nil {
return err
}
*sboxOptions = append(*sboxOptions, libnetwork.OptionHostsPath(container.HostsPath))
container.ResolvConfPath, err = container.GetRootResourcePath("resolv.conf")
if err != nil {
return err
}
*sboxOptions = append(*sboxOptions, libnetwork.OptionResolvConfPath(container.ResolvConfPath))
return nil
}
func (daemon *Daemon) initializeNetworkingPaths(container *container.Container, nc *container.Container) error {
container.HostnamePath = nc.HostnamePath
container.HostsPath = nc.HostsPath
container.ResolvConfPath = nc.ResolvConfPath
return nil
}
func (daemon *Daemon) setupContainerMountsRoot(c *container.Container) error {
// get the root mount path so we can make it unbindable
p, err := c.MountsResourcePath("")
if err != nil {
return err
}
return idtools.MkdirAllAndChown(p, 0710, idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: daemon.IdentityMapping().RootPair().GID})
}