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Set up DNS server in containerized mounter path

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During NFS/GlusterFS mount, it requires to have DNS server to be able to
resolve service name. This PR gets the DNS server ip from kubelet and
add it to the containerized mounter path. So if containerized mounter is
used, service name could be resolved during mount
This commit is contained in:
Jing Xu 2017-08-25 14:15:37 -07:00
parent 775f5d232d
commit 3d4bc931d3
2 changed files with 37 additions and 1 deletions
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2
cluster/gce/gci/configure-helper.sh
View File

@ -1201,7 +1201,7 @@ function prepare-mounter-rootfs {
mount --make-rshared "${CONTAINERIZED_MOUNTER_ROOTFS}/var/lib/kubelet"
mount --bind -o ro /proc "${CONTAINERIZED_MOUNTER_ROOTFS}/proc"
mount --bind -o ro /dev "${CONTAINERIZED_MOUNTER_ROOTFS}/dev"
mount --bind -o ro /etc/resolv.conf "${CONTAINERIZED_MOUNTER_ROOTFS}/etc/resolv.conf"
cp /etc/resolv.conf "${CONTAINERIZED_MOUNTER_ROOTFS}/etc/"
}
# A helper function for removing salt configuration and comments from a file.

36
pkg/kubelet/kubelet.go
View File

@ -19,11 +19,13 @@ package kubelet
import (
"crypto/tls"
"fmt"
"io/ioutil"
"net"
"net/http"
"net/url"
"os"
"path"
"path/filepath"
"sort"
"strings"
"sync"
@ -760,7 +762,11 @@ func NewMainKubelet(kubeCfg *kubeletconfiginternal.KubeletConfiguration,
// check node capabilities since the mount path is not the default
if len(kubeCfg.ExperimentalMounterPath) != 0 {
kubeCfg.ExperimentalCheckNodeCapabilitiesBeforeMount = false
// Replace the nameserver in containerized-mounter's rootfs/etc/resolve.conf with kubelet.ClusterDNS
// so that service name could be resolved
klet.setupDNSinContainerizedMounter(kubeCfg.ExperimentalMounterPath)
}
// setup volumeManager
klet.volumeManager = volumemanager.NewVolumeManager(
kubeCfg.EnableControllerAttachDetach,
@ -2141,6 +2147,36 @@ func (kl *Kubelet) cleanUpContainersInPod(podID types.UID, exitedContainerID str
}
}
// Replace the nameserver in containerized-mounter's rootfs/etc/resolve.conf with kubelet.ClusterDNS
func (kl *Kubelet) setupDNSinContainerizedMounter(mounterPath string) {
resolvePath := filepath.Join(strings.TrimSuffix(mounterPath, "/mounter"), "rootfs", "etc", "resolv.conf")
dnsString := ""
for _, dns := range kl.clusterDNS {
dnsString = dnsString + fmt.Sprintf("nameserver %s\n", dns)
}
if kl.resolverConfig != "" {
f, err := os.Open(kl.resolverConfig)
defer f.Close()
if err != nil {
glog.Error("Could not open resolverConf file")
} else {
_, hostSearch, err := kl.parseResolvConf(f)
if err != nil {
glog.Errorf("Error for parsing the reslov.conf file: %v", err)
} else {
dnsString = dnsString + "search"
for _, search := range hostSearch {
dnsString = dnsString + fmt.Sprintf(" %s", search)
}
dnsString = dnsString + "\n"
}
}
}
if err := ioutil.WriteFile(resolvePath, []byte(dnsString), 0600); err != nil {
glog.Errorf("Could not write dns nameserver in file %s, with error %v", resolvePath, err)
}
}
// isSyncPodWorthy filters out events that are not worthy of pod syncing
func isSyncPodWorthy(event *pleg.PodLifecycleEvent) bool {
// ContatnerRemoved doesn't affect pod state