moby/daemon/container_operations_windows.go
Rob Murray 6c68be24a2 Windows DNS resolver forwarding
Make the internal DNS resolver for Windows containers forward requests
to upsteam DNS servers when it cannot respond itself, rather than
returning SERVFAIL.

Windows containers are normally configured with the internal resolver
first for service discovery (container name lookup), then external
resolvers from '--dns' or the host's networking configuration.

When a tool like ping gets a SERVFAIL from the internal resolver, it
tries the other nameservers. But, nslookup does not, and with this
change it does not need to.

The internal resolver learns external server addresses from the
container's HNSEndpoint configuration, so it will use the same DNS
servers as processes in the container.

The internal resolver for Windows containers listens on the network's
gateway address, and each container may have a different set of external
DNS servers. So, the resolver uses the source address of the DNS request
to select external resolvers.

On Windows, daemon.json feature option 'windows-no-dns-proxy' can be used
to prevent the internal resolver from forwarding requests (restoring the
old behaviour).

Signed-off-by: Rob Murray <rob.murray@docker.com>
2024-04-16 18:57:28 +01:00

214 lines
6 KiB
Go

package daemon // import "github.com/docker/docker/daemon"
import (
"context"
"fmt"
"os"
"github.com/containerd/log"
"github.com/docker/docker/container"
"github.com/docker/docker/daemon/config"
"github.com/docker/docker/libnetwork"
"github.com/docker/docker/pkg/system"
"github.com/pkg/errors"
)
func (daemon *Daemon) setupLinkedContainers(container *container.Container) ([]string, error) {
return nil, nil
}
func (daemon *Daemon) setupConfigDir(c *container.Container) (setupErr error) {
if len(c.ConfigReferences) == 0 {
return nil
}
localPath := c.ConfigsDirPath()
log.G(context.TODO()).Debugf("configs: setting up config dir: %s", localPath)
// create local config root
if err := system.MkdirAllWithACL(localPath, 0, system.SddlAdministratorsLocalSystem); err != nil {
return errors.Wrap(err, "error creating config dir")
}
defer func() {
if setupErr != nil {
if err := os.RemoveAll(localPath); err != nil {
log.G(context.TODO()).Errorf("error cleaning up config dir: %s", err)
}
}
}()
if c.DependencyStore == nil {
return fmt.Errorf("config store is not initialized")
}
for _, configRef := range c.ConfigReferences {
// TODO (ehazlett): use type switch when more are supported
if configRef.File == nil {
// Runtime configs are not mounted into the container, but they're
// a valid type of config so we should not error when we encounter
// one.
if configRef.Runtime == nil {
log.G(context.TODO()).Error("config target type is not a file or runtime target")
}
// However, in any case, this isn't a file config, so we have no
// further work to do
continue
}
fPath, err := c.ConfigFilePath(*configRef)
if err != nil {
return errors.Wrap(err, "error getting config file path for container")
}
log := log.G(context.TODO()).WithFields(log.Fields{"name": configRef.File.Name, "path": fPath})
log.Debug("injecting config")
config, err := c.DependencyStore.Configs().Get(configRef.ConfigID)
if err != nil {
return errors.Wrap(err, "unable to get config from config store")
}
if err := os.WriteFile(fPath, config.Spec.Data, configRef.File.Mode); err != nil {
return errors.Wrap(err, "error injecting config")
}
}
return nil
}
func (daemon *Daemon) setupIpcDirs(container *container.Container) error {
return nil
}
// TODO Windows: Fix Post-TP5. This is a hack to allow docker cp to work
// against containers which have volumes. You will still be able to cp
// to somewhere on the container drive, but not to any mounted volumes
// inside the container. Without this fix, docker cp is broken to any
// container which has a volume, regardless of where the file is inside the
// container.
func (daemon *Daemon) mountVolumes(container *container.Container) error {
return nil
}
func (daemon *Daemon) setupSecretDir(c *container.Container) (setupErr error) {
if len(c.SecretReferences) == 0 {
return nil
}
localMountPath, err := c.SecretMountPath()
if err != nil {
return err
}
log.G(context.TODO()).Debugf("secrets: setting up secret dir: %s", localMountPath)
// create local secret root
if err := system.MkdirAllWithACL(localMountPath, 0, system.SddlAdministratorsLocalSystem); err != nil {
return errors.Wrap(err, "error creating secret local directory")
}
defer func() {
if setupErr != nil {
if err := os.RemoveAll(localMountPath); err != nil {
log.G(context.TODO()).Errorf("error cleaning up secret mount: %s", err)
}
}
}()
if c.DependencyStore == nil {
return fmt.Errorf("secret store is not initialized")
}
for _, s := range c.SecretReferences {
// TODO (ehazlett): use type switch when more are supported
if s.File == nil {
log.G(context.TODO()).Error("secret target type is not a file target")
continue
}
// secrets are created in the SecretMountPath on the host, at a
// single level
fPath, err := c.SecretFilePath(*s)
if err != nil {
return err
}
log.G(context.TODO()).WithFields(log.Fields{
"name": s.File.Name,
"path": fPath,
}).Debug("injecting secret")
secret, err := c.DependencyStore.Secrets().Get(s.SecretID)
if err != nil {
return errors.Wrap(err, "unable to get secret from secret store")
}
if err := os.WriteFile(fPath, secret.Spec.Data, s.File.Mode); err != nil {
return errors.Wrap(err, "error injecting secret")
}
}
return nil
}
func killProcessDirectly(container *container.Container) error {
return nil
}
func isLinkable(child *container.Container) bool {
return false
}
func enableIPOnPredefinedNetwork() bool {
return true
}
// serviceDiscoveryOnDefaultNetwork indicates if service discovery is supported on the default network
func serviceDiscoveryOnDefaultNetwork() bool {
return true
}
func buildSandboxPlatformOptions(container *container.Container, cfg *config.Config, sboxOptions *[]libnetwork.SandboxOption) error {
// By default, the Windows internal resolver does not forward requests to
// external resolvers - but forwarding can be enabled using feature flag
// "windows-dns-proxy":true.
if doproxy, exists := cfg.Features["windows-dns-proxy"]; !exists || !doproxy {
*sboxOptions = append(*sboxOptions, libnetwork.OptionDNSNoProxy())
}
return nil
}
func (daemon *Daemon) initializeNetworkingPaths(container *container.Container, nc *container.Container) error {
if nc.HostConfig.Isolation.IsHyperV() {
return fmt.Errorf("sharing of hyperv containers network is not supported")
}
container.NetworkSharedContainerID = nc.ID
if nc.NetworkSettings != nil {
for n := range nc.NetworkSettings.Networks {
sn, err := daemon.FindNetwork(n)
if err != nil {
continue
}
ep, err := getEndpointInNetwork(nc.Name, sn)
if err != nil {
continue
}
data, err := ep.DriverInfo()
if err != nil {
continue
}
if data["GW_INFO"] != nil {
gwInfo := data["GW_INFO"].(map[string]interface{})
if gwInfo["hnsid"] != nil {
container.SharedEndpointList = append(container.SharedEndpointList, gwInfo["hnsid"].(string))
}
}
if data["hnsid"] != nil {
container.SharedEndpointList = append(container.SharedEndpointList, data["hnsid"].(string))
}
}
}
return nil
}