Recently I upgraded Kubernetes cluster from version 1.5.3 to 1.6.1 using kubeadm
.
Now I would like to upgrade from version 1.6.1 to 1.6.2 but I'm facing this error:
[root@master ~]#kubeadm upgrade plan --v=5
I1113 14:14:31.046080 8368 plan.go:67] [upgrade/plan] verifying health of cluster
I1113 14:14:31.046233 8368 plan.go:68] [upgrade/plan] retrieving configuration from cluster
[upgrade/config] Making sure the configuration is correct:
[upgrade/config] Reading configuration from the cluster...
[upgrade/config] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
I1113 14:14:31.111668 8368 common.go:122] running preflight checks
[preflight] Running pre-flight checks.
I1113 14:14:31.111843 8368 preflight.go:78] validating if there are any unsupported CoreDNS plugins in the Corefile
I1113 14:14:31.143841 8368 preflight.go:103] validating if migration can be done for the current CoreDNS release.
[preflight] Some fatal errors occurred:
[ERROR CoreDNSUnsupportedPlugins]: start version '' not supported
[ERROR CoreDNSMigration]: start version '' not supported
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
It seems that kubeadm
is not able to resolve CoreDNS version.
Here is the CoreDNS config:
apiVersion: v1
data:
Corefile: |
.:53 {
errors
health
ready
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
fallthrough in-addr.arpa ip6.arpa
ttl 30
}
prometheus :9153
forward . /etc/resolv.conf
cache 30
loop
reload
loadbalance
}
kind: ConfigMap
metadata:
creationTimestamp: "2018-12-15T00:02:45Z"
name: coredns
namespace: kube-system
resourceVersion: "45537229"
selfLink: /api/v1/namespaces/kube-system/configmaps/coredns
uid: c01fbb58-fffc-11e8-9a01-005056a31666
From where it is reading the version number? Or what can I do to solve this error?
Best Answer
You received failed
CoreDNSUnsupportedPlugins
check due toproxy
plugin that has been replaced withforward
plugin. Here you can find more information about that.There are two ways to solve this:
One is to ignore checks using
--ignore-preflight-errors=CoreDNSUnsupportedPlugins
at the time of the upgrade.Second one is to replace
proxy . /etc/resolv.conf
from coredns configMap withforward
.It should look like this:forward . /etc/resolv.conf
You can find more information about the same problem here