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Merge pull request #63691 from detiber/warn_systemd-resolved

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Automatic merge from submit-queue (batch tested with PRs 63673, 63712, 63691, 63684). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

kubeadm - add preflight warning when using systemd-resolved

**What this PR does / why we need it**:

This PR adds a preflight warning when the host is running systemd-resolved.

Newer Ubuntu releases (artful and bionic in particular) run systemd-resolved by default and in the dfeault configuration have an /etc/resolv.conf file that references 127.0.0.53 which is not accessible from containers running on the host. We will now provide a warning to the user to tell them that the kubelet args should include `--resolv-conf=/run/systemd/resolve/resolv.conf`. `/run/systemd/resolve/resolv.conf`. 

**Which issue(s) this PR fixes**:
This does not resolve the following issues, but it does provide better output to the users affected by the issues: https://github.com/kubernetes/kubeadm/issues/273 https://github.com/kubernetes/kubeadm/issues/787

**Release note**:
```release-note
NONE
```
This commit is contained in:
Kubernetes Submit Queue 2018-05-11 09:49:10 -07:00 committed by GitHub
commit fc28923e71
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2 changed files with 31 additions and 1 deletions
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1
cmd/kubeadm/app/preflight/BUILD
View File

@ -56,6 +56,7 @@ go_library(
"//pkg/kubeapiserver/authorizer/modes:go_default_library",
"//pkg/registry/core/service/ipallocator:go_default_library",
"//pkg/util/initsystem:go_default_library",
"//pkg/util/procfs:go_default_library",
"//pkg/util/version:go_default_library",
"//pkg/version:go_default_library",
"//test/e2e_node/system:go_default_library",

31
cmd/kubeadm/app/preflight/checks.go
View File

@ -50,6 +50,7 @@ import (
authzmodes "k8s.io/kubernetes/pkg/kubeapiserver/authorizer/modes"
"k8s.io/kubernetes/pkg/registry/core/service/ipallocator"
"k8s.io/kubernetes/pkg/util/initsystem"
"k8s.io/kubernetes/pkg/util/procfs"
versionutil "k8s.io/kubernetes/pkg/util/version"
kubeadmversion "k8s.io/kubernetes/pkg/version"
"k8s.io/kubernetes/test/e2e_node/system"
@ -813,6 +814,33 @@ func getEtcdVersionResponse(client *http.Client, url string, target interface{})
return err
}
// ResolveCheck tests for potential issues related to the system resolver configuration
type ResolveCheck struct{}
// Name returns label for ResolveCheck
func (ResolveCheck) Name() string {
return "Resolve"
}
// Check validates the system resolver configuration
func (ResolveCheck) Check() (warnings, errors []error) {
glog.V(1).Infoln("validating the system resolver configuration")
warnings = []error{}
// procfs.PidOf only returns an error if the string passed is empty
// or there is an issue compiling the regex, so we can ignore it here
pids, _ := procfs.PidOf("systemd-resolved")
if len(pids) > 0 {
warnings = append(warnings, fmt.Errorf(
"systemd-resolved was detected, for cluster dns resolution to work "+
"properly --resolv-conf=/run/systemd/resolve/resolv.conf must be set "+
"for the kubelet. (/etc/systemd/system/kubelet.service.d/10-kubeadm.conf should be edited for this purpose)\n"))
}
return warnings, errors
}
// RunInitMasterChecks executes all individual, applicable to Master node checks.
func RunInitMasterChecks(execer utilsexec.Interface, cfg *kubeadmapi.MasterConfiguration, ignorePreflightErrors sets.String) error {
// First, check if we're root separately from the other preflight checks and fail fast
@ -951,7 +979,8 @@ func addCommonChecks(execer utilsexec.Interface, cfg kubeadmapi.CommonConfigurat
InPathCheck{executable: "socat", mandatory: false, exec: execer},
InPathCheck{executable: "tc", mandatory: false, exec: execer},
InPathCheck{executable: "touch", mandatory: false, exec: execer},
criCtlChecker)
criCtlChecker,
ResolveCheck{})
}
checks = append(checks,
SystemVerificationCheck{CRISocket: cfg.GetCRISocket()},