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Rewrite resolv.conf for dockershim

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PR #29378 introduces ClusterFirstWithHostNet, but docker doesn't support
setting dns options togather with hostnetwork. This commit rewrites
resolv.conf same as dockertools.
This commit is contained in:
Pengfei Ni
2017-03-20 18:45:39 +08:00
parent 079158fa08
commit 95c3782043
2 changed files with 23 additions and 9 deletions
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26
pkg/kubelet/dockershim/docker_sandbox.go
View File

@@ -92,6 +92,25 @@ func (ds *dockerService) RunPodSandbox(config *runtimeapi.PodSandboxConfig) (str
if err != nil {
return createResp.ID, fmt.Errorf("failed to start sandbox container for pod %q: %v", config.Metadata.Name, err)
}
// Rewrite resolv.conf file generated by docker.
// NOTE: cluster dns settings aren't passed anymore to docker api in all cases,
// not only for pods with host network: the resolver conf will be overwritten
// after sandbox creation to override docker's behaviour. This resolv.conf
// file is shared by all containers of the same pod, and needs to be modified
// only once per pod.
if dnsConfig := config.GetDnsConfig(); dnsConfig != nil {
containerInfo, err := ds.client.InspectContainer(createResp.ID)
if err != nil {
return createResp.ID, fmt.Errorf("failed to inspect sandbox container for pod %q: %v", config.Metadata.Name, err)
}
if err := dockertools.RewriteResolvFile(containerInfo.ResolvConfPath, dnsConfig.Servers, dnsConfig.Searches, len(dnsConfig.Options) > 0); err != nil {
return createResp.ID, fmt.Errorf("rewrite resolf.conf faield for pod %q: %v", config.Metadata.Name, err)
}
}
// Do not invoke network plugins if in hostNetwork mode.
if nsOptions := config.GetLinux().GetSecurityContext().GetNamespaceOptions(); nsOptions != nil && nsOptions.HostNetwork {
return createResp.ID, nil
}
@@ -486,13 +505,6 @@ func (ds *dockerService) makeSandboxDockerConfig(c *runtimeapi.PodSandboxConfig,
createConfig.Config.ExposedPorts = exposedPorts
hc.PortBindings = portBindings
// Set DNS options.
if dnsConfig := c.GetDnsConfig(); dnsConfig != nil {
hc.DNS = dnsConfig.Servers
hc.DNSSearch = dnsConfig.Searches
hc.DNSOptions = dnsConfig.Options
}
// Apply resource options.
setSandboxResources(hc)

6
pkg/kubelet/dockertools/docker_manager.go
View File

@@ -1834,7 +1834,7 @@ func (dm *DockerManager) runContainerInPod(pod *v1.Pod, container *v1.Container,
// we modify it when the pause container is created since it is the first container created in the pod since it holds
// the networking namespace.
if container.Name == PodInfraContainerName {
if err := rewriteResolvFile(containerInfo.ResolvConfPath, opts.DNS, opts.DNSSearch, useClusterFirstPolicy); err != nil {
if err := RewriteResolvFile(containerInfo.ResolvConfPath, opts.DNS, opts.DNSSearch, useClusterFirstPolicy); err != nil {
return kubecontainer.ContainerID{}, err
}
}
@@ -1900,7 +1900,9 @@ func (dm *DockerManager) checkDockerAPIVersion(expectedVersion string) (int, err
return result, nil
}
func rewriteResolvFile(resolvFilePath string, dns []string, dnsSearch []string, useClusterFirstPolicy bool) error {
// RewriteResolvFile rewrites resolv.conf file generated by docker.
// Exported for reusing in dockershim.
func RewriteResolvFile(resolvFilePath string, dns []string, dnsSearch []string, useClusterFirstPolicy bool) error {
if len(resolvFilePath) == 0 {
glog.Errorf("ResolvConfPath is empty.")
return nil