kubeadm init does not configure RBAC for configmaps correctly

Created on 9 Jun 2018  ·  17Comments  ·  Source: kubernetes/kubeadm

Is this a BUG REPORT or FEATURE REQUEST?

BUG REPORT

Versions

kubeadm version (use kubeadm version): "v1.12.0-alpha.0.957+1235adac3802fd-dirty"

What happened?

I created a control plane node with kubeadm init. I ran kubeadm join on a separate node and got this error message:

[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace                                                                        
configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:4ipkdk" cannot get configmaps in the namespace "kube-system"

What you expected to happen?

I expected kubeadm join to successfully finish

How to reproduce it (as minimally and precisely as possible)?

As far as I can tell, run kubeadm init and kubeadm join on another node. I have a lot of extra code/yaml that shouldn't be influencing the config map (required for happy aws deployment). But if this turns out to not be reproducible I will provide more indepth instructions.

Anything else we need to know?

I think also kubeadm join and kubeadm init are naming the config maps inconsistently. The init command uses the kubernetesVersion specified in the config file and the join command uses the kubelet version for the name of the config map (e.g. kubelet-config-1.1). This is fine unless you have mismatched versions then it is not fine.

The init command makes RBAC rules for anonymous access to config maps in the kube-public namespace but it doesn't seem to put the kubelet config in the public namespace and thus the node joining has no access to it.

kinbug prioritimportant-longterm
Source
picture chuckha

Most helpful comment

This is fine unless you have mismatched versions then it is not fine.

text

picture neolit123 on 9 Jun 2018
😄22 👍7

All 17 comments

This is fine unless you have mismatched versions then it is not fine.

text

neolit123 picture neolit123 on 9 Jun 2018
😄22 👍7

@chuckha If I remember well kubelet-* config maps should be kube-system and kubeadm creates rules for allowing access to bootstrap token and nodes. But I'm going to check this again after last round of changes

fabriziopandini picture fabriziopandini on 11 Jun 2018

@chuckha I completed join successfully on a cluster with all the components build from master + release number forced to v1.11.0

  • kubelet-config-1.11 was created in kube-system
  • role kubeadm:kubelet-config-1.11 was created in kube-system with get permission on the config map
  • rolebinding kubeadm:kubelet-config-1.11 was created in kube-system for system:nodes and system:bootstrappers:kubeadm:default-node-token

So IMO:

  • RBAC are created
  • if we are in "version consistent" scenario, everything works

The part still to investigate is

The init command uses the kubernetesVersion specified in the config file and the join command uses the kubelet version for the name of the config map (e.g. kubelet-config-1.1)

fabriziopandini picture fabriziopandini on 11 Jun 2018
👍2

Yes, this must be a version issue.

I didn't set the version when I built so the binaries all think they are 1.12.0+ but I installed and forced kubeadm to use v1.11.

This resulted in 

root@ip-10-0-0-7:~# k get cm -n kube-system
NAME                                 DATA      AGE
...
kubelet-config-1.11                  1         32m

and then when joining:

[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace                                                                        
configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:u3ns6m" cannot get configmaps in the namespace "kube-system"

I will rebuild the binaries and force them to the correct version and try again.

chuckha picture chuckha on 11 Jun 2018

Everything is fine when versions of kubelet and kubeadm match. Closing in favor of a less urgent fix regarding inconsistency (maybe intentional) between writing config map and fetching configmap.

chuckha picture chuckha on 11 Jun 2018

I'm not using kubeadm init, but calling the phases individually. There is no configmap in kube-system nor permissions to properly set it up. What phase is this?

drewwells picture drewwells on 9 Aug 2018

@drewwells I have encountered the same problem as you did. I am running the phases individually, and there are no config mpas.

sudo kubectl get cm -n kube-system --kubeconfig=/etc/kubernetes/admin.conf
NAME                                 DATA   AGE
calico-config                        2      11m
coredns                              1      15m
extension-apiserver-authentication   6      15m
kube-proxy                           2      15m

Have you found the solution?

I must also mention, all components are 1.11.4

This goes further. I bootstrap a cluster with kubeadm init, and I do have the correct config map in place now:

ubuntu@master-1-test2:~$ sudo kubectl get cm -n kube-system --kubeconfig=/etc/kubernetes/admin.conf
NAME                                 DATA      AGE
coredns                              1         41m
extension-apiserver-authentication   6         41m
kube-proxy                           2         41m
kubeadm-config                       1         41m
kubelet-config-1.11                  1         41m
ubuntu@master-1-test2:~$ kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"11", GitVersion:"v1.11.4", GitCommit:"bf9a868e8ea3d3a8fa53cbb22f566771b3f8068b", GitTreeState:"clean", BuildDate:"2018-10-25T19:13:39Z", GoVersion:"go1.10.3", Compiler:"gc", Platform:"linux/amd64"}

On the node:

$ sudo kubeadm -v=10 join k8s.oz.noris.de:6443 --token 36etul.nv5lz6hjfifdd4c9 --discovery-token-unsafe-skip-ca-verification                                                                                             I1107 12:57:01.340638    3631 join.go:226] [join] found NodeName empty
I1107 12:57:01.340816    3631 join.go:227] [join] considered OS hostname as NodeName
[preflight] running pre-flight checks
I1107 12:57:01.341152    3631 join.go:238] [preflight] running various checks on all nodes
I1107 12:57:01.341265    3631 checks.go:253] validating the existence and emptiness of directory /etc/kubernetes/manifests
I1107 12:57:01.341677    3631 checks.go:291] validating the existence of file /etc/kubernetes/pki/ca.crt
I1107 12:57:01.341774    3631 checks.go:291] validating the existence of file /etc/kubernetes/kubelet.conf
I1107 12:57:01.341857    3631 checks.go:291] validating the existence of file /etc/kubernetes/bootstrap-kubelet.conf
I1107 12:57:01.341947    3631 kernelcheck_linux.go:45] validating the kernel module IPVS required exists in machine or not
        [WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs_sh ip_vs ip_vs_rr ip_vs_wrr] or no builtin kernel ipvs support: map[ip_vs:{} ip_
vs_rr:{} ip_vs_wrr:{} ip_vs_sh:{} nf_conntrack_ipv4:{}]
you can solve this problem with following methods:
 1. Run 'modprobe -- ' to load missing kernel modules;
2. Provide the missing builtin kernel ipvs support

I1107 12:57:01.349448    3631 checks.go:138] validating if the service is enabled and active
I1107 12:57:01.361957    3631 checks.go:340] validating the contents of file /proc/sys/net/bridge/bridge-nf-call-iptables
I1107 12:57:01.362034    3631 checks.go:340] validating the contents of file /proc/sys/net/ipv4/ip_forward
I1107 12:57:01.362076    3631 checks.go:653] validating whether swap is enabled or not
I1107 12:57:01.362134    3631 checks.go:381] validating the presence of executable crictl
I1107 12:57:01.362204    3631 checks.go:381] validating the presence of executable ip
I1107 12:57:01.362244    3631 checks.go:381] validating the presence of executable iptables
I1107 12:57:01.362281    3631 checks.go:381] validating the presence of executable mount
I1107 12:57:01.362320    3631 checks.go:381] validating the presence of executable nsenter
...
[discovery] Trying to connect to API Server "mycluster.example.com:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://mycluster.example.com:6443"
I1107 12:57:01.487256    3631 round_trippers.go:386] curl -k -v -XGET  -H "Accept: application/json, */*" -H "User-Agent: kubeadm/v1.11.4 (linux/amd64) kubernetes/bf9a868" 'https://mycluster.example.com:6443/api/v1/namespaces/kube-public/config
maps/cluster-info'
I1107 12:57:01.504539    3631 round_trippers.go:405] GET https://mycluster.example.com:6443/api/v1/namespaces/kube-public/configmaps/cluster-info 200 OK in 17 milliseconds
I1107 12:57:01.504720    3631 round_trippers.go:411] Response Headers:
I1107 12:57:01.504818    3631 round_trippers.go:414]     Content-Type: application/json
I1107 12:57:01.504914    3631 round_trippers.go:414]     Content-Length: 2217
I1107 12:57:01.505003    3631 round_trippers.go:414]     Date: Wed, 07 Nov 2018 12:57:01 GMT
I1107 12:57:01.505174    3631 request.go:942] Response Body: {"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"cluster-info","namespace":"kube-public","selfLink":"/api/v1/namespaces/kube-public/configmaps/cluster-info","uid":"97e9
a3d1-e286-11e8-9272-fa163ef9e3af","resourceVersion":"425","creationTimestamp":"2018-11-07T12:13:53Z"},"data":{"jws-kubeconfig-36etul":"eyJhbGciOiJIUzI1NiIsImtpZCI6IjM2ZXR1bCJ9..zRgexonkjOpLJS0q3IignURwTcpBuQy7gv35Qhhsl_k","jws-kubeconfig-
eth6o8":"eyJhbGciOiJIUzI1NiIsImtpZCI6ImV0aDZvOCJ9..kWj4cI2j1WgKfNG07IGiIij4CSb9kWUbaM2mixlYThY","jws-kubeconfig-rbxd02":"eyJhbGciOiJIUzI1NiIsImtpZCI6InJieGQwMiJ9..HwIWDwfIbAjNM1EGbWdXYOhC8z1MxgwuzhjlJRaZ_pc","kubeconfig":"apiVersion: v1\n
clusters:\n- cluster:\n    certificate-authority-data: LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUN5RENDQWJDZ0F3SUJBZ0lCQURBTkJna3Foa2lHOXcwQkFRc0ZBREFWTVJNd0VRWURWUVFERXdwcmRXSmwKY201bGRHVnpNQjRYRFRFNE1URXdNekEwTlRrME4xb1hEVEk0TVRBek1UQTB
OVGswTjFvd0ZURVRNQkVHQTFVRQpBeE1LYTNWaVpYSnVaWFJsY3pDQ0FTSXdEUVlKS29aSWh2Y05BUUVCQlFBRGdnRVBBRENDQVFvQ2dnRUJBTU9BCkNHQU5jUjVRQWV3MlljY2V0eWVyYktiODd4RWRPVlp2aUdneElrbkpKTTZwZFVBbzMwSWVxckRqSnlFaTFVeDcKU0c5NS9sRlBqU1htdHhhNHMvc1g1KzNTVW4zZ
EtFRWw5TFhXa0lzeTRJYzRFUTMwWE9WcnNuYTYwN1UzNmQyaAp3NHdTK1dveE5QR3dqZDM2bXQzMFR4bUluYk54ZVl5d2NnVU1tMlZFZXM4dGhVaVhZMXB1N1Y2SUNCY243cE9NCkdoT2xlRXg4SmlEVnhuSGlpSm9oYytCbGNIdHdLU1pzK2cvZUhwdGdlSDdaQlZNRC8zZVFvZXVsUGVvTEkwamEKc09jTENMTkpEVVB
LUWJqRnRNbkFZSXVvOENHSXpFTzBDaDZNeW5vb1pTL0E0bEs1MXJmTVdkTkZ4N0dVdnQxYQo5KzZzMHo2NEpHeVFBdmtBcWhVQ0F3RUFBYU1qTUNFd0RnWURWUjBQQVFIL0JBUURBZ0trTUE4R0ExVWRFd0VCCi93UUZNQU1CQWY4d0RRWUpLb1pJaHZjTkFRRUxCUUFEZ2dFQkFEbWs1NEYzZ1BqOS91NzlRbTg2V1Mzc
k5YaFoKZG16Wmt3TXRDajRuTXdsSndGQy9iZUU4ZUdsWnFxWDcrdEpYUDVaY0xLNE1pSnM1U2JTMjd5NDF3WTRRTFFWaQpVWmRocEFHUTBOSlpHSGhWMTVDczlVQTA1ZTFNajNCaHZ6SG5VV2t1ZUhYbW84VmI4SkI5RGloeGdiUW5GY2FQCjRWcVhWY0pBemxVQ0V5aXhreVRGendZTklJbzJHdGtCdlI1YkxCM0doT2R
sQURmQzEwdzgvTmQveFFmRnRWdmYKL3lHaktpbW8rT2xERkV5YittcHVKMVdiN3Y3bnJJSzlSSy9WbVhUWENiOWZLQ3BmQ0hMU0hpa0lEWklZK0wxTQpwbWpXYXZFcjFLSlE5UEJIYmdZSHkxK1F0bkpXRDNjNnJrOUtoNU1zMFhTVmpBc2Z1RWdXaG9CYnlVdz0KLS0tLS1FTkQgQ0VSVElGSUNBVEUtLS0tLQo=\n   
 server: https://k8s.oz.noris.de:6443\n  name: \"\"\ncontexts: []\ncurrent-context: \"\"\nkind: Config\npreferences: {}\nusers: []\n"}}
[discovery] Cluster info signature and contents are valid and no TLS pinning was specified, will use API Server "k8s.oz.noris.de:6443"
[discovery] Successfully established connection with API Server "mycluster.example.com:6443"
I1107 12:57:01.509945    3631 join.go:260] [join] writing bootstrap kubelet config file at /etc/kubernetes/bootstrap-kubelet.conf
I1107 12:57:01.617006    3631 loader.go:359] Config loaded from file /etc/kubernetes/bootstrap-kubelet.conf
I1107 12:57:01.617871    3631 join.go:283] Stopping the kubelet
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace
I1107 12:57:01.627838    3631 round_trippers.go:386] curl -k -v -XGET  -H "Accept: application/json, */*" -H "User-Agent: kubeadm/v1.11.4 (linux/amd64) kubernetes/bf9a868" -H "Authorization: Bearer 36etul.nv5lz6hjfifdd4c9" 'https://mycluster.example.com:6443/api/v1/namespaces/kube-system/configmaps/kubelet-config-1.12'
I1107 12:57:01.639396    3631 round_trippers.go:405] GET https://mycluster.example.com:6443/api/v1/namespaces/kube-system/configmaps/kubelet-config-1.12 403 Forbidden in 11 milliseconds
I1107 12:57:01.639427    3631 round_trippers.go:411] Response Headers:
I1107 12:57:01.639443    3631 round_trippers.go:414]     Content-Length: 311
I1107 12:57:01.639464    3631 round_trippers.go:414]     Date: Wed, 07 Nov 2018 12:57:01 GMT
I1107 12:57:01.639477    3631 round_trippers.go:414]     Content-Type: application/json
I1107 12:57:01.639492    3631 round_trippers.go:414]     X-Content-Type-Options: nosniff
I1107 12:57:01.639525    3631 request.go:942] Response Body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"configmaps \"kubelet-config-1.12\" is forbidden: User \"system:bootstrap:36etul\" cannot get confi
gmaps in the namespace \"kube-system\"","reason":"Forbidden","details":{"name":"kubelet-config-1.12","kind":"configmaps"},"code":403}
configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:36etul" cannot get configmaps in the namespace "kube-system"

notice the weired stuff? It's trying to fetch config map in version 1.12

Apparently, that all makes since, if you check the version of the kubelet! I have had kubelet version 1.12.2.
I got the hint from the code

oz123 picture oz123 on 7 Nov 2018

I'm experiencing the same problem, except one version newer.

On the master:

$ lsb_release -d
Description:    Ubuntu 16.04.5 LTS
$ dpkg -l | grep kub
ii  kubeadm                          1.12.1-00                                  amd64        Kubernetes Cluster Bootstrapping Tool
ii  kubectl                          1.12.1-00                                  amd64        Kubernetes Command Line Tool
ii  kubelet                          1.12.1-00                                  amd64        Kubernetes Node Agent
ii  kubernetes-cni                   0.6.0-00                                   amd64        Kubernetes CNI
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.1", GitCommit:"4ed3216f3ec431b140b1d899130a69fc671678f4", GitTreeState:"clean", BuildDate:"2018-10-05T16:46:06Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T20:56:12Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}

What, where did that server version 1.13.0 come from? I didn't install that.

Anyway, before I ran kubeadm init on this VM, I cloned it, so I have another one ready to be another node in the cluster. Because it's a clone, it also has 1.12.1. When I try to join it:

$ kubeadm join --token blahblah 10.138.0.3:6443 --discovery-token-ca-cert-hash sha256:deadbeefdeadbeefetc 
[preflight] running pre-flight checks
        [WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs ip_vs_rr ip_vs_wrr ip_vs_sh] or no builtin kernel ipvs support: map[ip_vs_sh:{} nf_conntrack_ipv4:{} ip_vs:{} ip_vs_rr:{} ip_vs_wrr:{}]
you can solve this problem with following methods:
 1. Run 'modprobe -- ' to load missing kernel modules;
2. Provide the missing builtin kernel ipvs support
[discovery] Trying to connect to API Server "10.138.0.3:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://10.138.0.3:6443"
[discovery] Requesting info from "https://10.138.0.3:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will 
use API Server "10.138.0.3:6443"
[discovery] Successfully established connection with API Server "10.138.0.3:6443"
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:3ai26q" cannot get resource "configmaps" in API group "" in the namespace "kube-system"

And why can't it get the kubelet-config-1.12 configmap? 'Cause there isn't one. Back on the master:

$ sudo kubectl get cm -n kube-system --kubeconfig=/etc/kubernetes/admin.conf
NAME                                 DATA   AGE
calico-config                        4      26m
coredns                              1      29m
extension-apiserver-authentication   6      29m
kube-proxy                           2      29m
kubeadm-config                       2      29m
kubelet-config-1.13                  1      29m
brianriceca picture brianriceca on 7 Dec 2018

@brianriceca : facing exactly same issue as like you...any solution for this..

Master:ram@k8master1:~$ kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.1", GitCommit:"4ed3216f3ec431b140b1d899130a69fc671678f4", GitTreeState:"clean", BuildDate:"2018-10-05T16:43:08Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
ram@k8master1:~$ dpkg -l | grep kub
ii kubeadm 1.12.1-00 amd64 Kubernetes Cluster Bootstrapping Tool
ii kubectl 1.12.1-00 amd64 Kubernetes Command Line Tool
ii kubelet 1.12.1-00 amd64 Kubernetes Node Agent
ii kubernetes-cni 0.6.0-00 amd64 Kubernetes CNI
ram@k8master1:~$ kubectl version
Client Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.1", GitCommit:"4ed3216f3ec431b140b1d899130a69fc671678f4", GitTreeState:"clean", BuildDate:"2018-10-05T16:46:06Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T20:56:12Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}

ram@k8master1:~$ kubectl get node
NAME STATUS ROLES AGE VERSION
k8master1.example.com Ready master 101m v1.12.1
ram@k8master1:~$ kubectl get pods --all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system calico-node-r248v 2/2 Running 0 99m
kube-system coredns-869f847d58-72lqd 1/1 Running 0 101m
kube-system coredns-869f847d58-p2zzs 1/1 Running 0 101m
kube-system etcd-k8master1.example.com 1/1 Running 0 100m
kube-system kube-apiserver-k8master1.example.com 1/1 Running 0 100m
kube-system kube-controller-manager-k8master1.example.com 1/1 Running 0 100m
kube-system kube-proxy-77qbx 1/1 Running 0 101m
kube-system kube-scheduler-k8master1.example.com 1/1 Running 0 100m

Worker Nodes:
root@k8worker1:~# dpkg -l|grep -i kub
ii kubeadm 1.12.1-00 amd64 Kubernetes Cluster Bootstrapping Tool
ii kubectl 1.12.1-00 amd64 Kubernetes Command Line Tool
ii kubelet 1.12.1-00 amd64 Kubernetes Node Agent
ii kubernetes-cni 0.6.0-00 amd64 Kubernetes CNI
root@k8worker1:~# kubectl version
Client Version: version.Info{Major:"1", Minor:"12", GitVersion:"v1.12.1", GitCommit:"4ed3216f3ec431b140b1d899130a69fc671678f4", GitTreeState:"clean", BuildDate:"2018-10-05T16:46:06Z", GoVersion:"go1.10.4", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server localhost:8080 was refused - did you specify the right host or port?

root@k8worker1:~# kubeadm join 10.0.0.61:6443 --token xjxgqa.h2vnld3x9ztgf3pr --discovery-token-ca-cert-hash sha256:7c18b654b623ee84164bb0dfa79409c821398f1a968843446af525ec72e0fdad
[preflight] running pre-flight checks
[WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs ip_vs_rr ip_vs_wrr ip_vs_sh] or no builtin kernel ipvs support: map[nf_conntrack_ipv4:{} ip_vs:{} ip_vs_rr:{} ip_vs_wrr:{} ip_vs_sh:{}]
you can solve this problem with following methods:

  1. Run 'modprobe -- ' to load missing kernel modules;

    1. Provide the missing builtin kernel ipvs support

[discovery] Trying to connect to API Server "10.0.0.61:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://10.0.0.61:6443"
[discovery] Requesting info from "https://10.0.0.61:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "10.0.0.61:6443"
[discovery] Successfully established connection with API Server "10.0.0.61:6443"
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace
configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:xjxgqa" cannot get resource "configmaps" in API group "" in the namespace "kube-system"
root@k8worker1:~# kubeadm join 10.0.0.61:6443 --token xjxgqa.h2vnld3x9ztgf3pr --discovery-token-ca-cert-hash sha256:7c18b654b623ee84164bb0dfa79409c821398f1a968843446af525ec72e0fdad
[preflight] running pre-flight checks
[WARNING RequiredIPVSKernelModulesAvailable]: the IPVS proxier will not be used, because the following required kernel modules are not loaded: [ip_vs ip_vs_rr ip_vs_wrr ip_vs_sh] or no builtin kernel ipvs support: map[ip_vs_rr:{} ip_vs_wrr:{} ip_vs_sh:{} nf_conntrack_ipv4:{} ip_vs:{}]
you can solve this problem with following methods:

  1. Run 'modprobe -- ' to load missing kernel modules;

    1. Provide the missing builtin kernel ipvs support

[preflight] Some fatal errors occurred:
[ERROR FileAvailable--etc-kubernetes-bootstrap-kubelet.conf]: /etc/kubernetes/bootstrap-kubelet.conf already exists
[ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists
[preflight] If you know what you are doing, you can make a check non-fatal with --ignore-preflight-errors=...

ramanjk picture ramanjk on 10 Dec 2018

same as @brianriceca and @ramanjk. Versions of kubadm and kubelet are 1.12.1 on both nodes, the kubelet-config-1.13 configmap is there, and seeing configmaps "kubelet-config-1.12" is forbidden as well

timwebster9 picture timwebster9 on 17 Dec 2018

D'oh! What I didn't yet know is that kubeadm always downloads the latest version of the Kubernetes control plane from gcr.io unless you tell it otherwise. So if I want to install 1.12.1 even when 1.13 is available, I need to do
kubeadm init --kubernetes-version 1.12.1 --pod-network-cidr _whatever/whatever_

brianriceca picture brianriceca on 17 Dec 2018
👍3

I deleted both nodes and tried again using version 1.12.2 of everything, and the problem didn't occur this time. There was some output about there being a newer version but that it will revert to 1.12 (I've lost it now)

timwebster9 picture timwebster9 on 17 Dec 2018

I am suffering the same bug, while (apparently) using the same version in the seeder as in the node.

On the seeder (after initialization):

$ kubeadm version -o json
{
  "clientVersion": {
    "major": "1",
    "minor": "13",
    "gitVersion": "v1.13.0",
    "gitCommit": "ddf47ac13c1a9483ea035a79cd7c10005ff21a6d",
    "gitTreeState": "clean",
    "buildDate": "2018-12-11T17:03:40Z",
    "goVersion": "go1.11.2",
    "compiler": "gc",
    "platform": "linux/amd64"
  }
}
$
$ kubectl get cm --all-namespaces
NAMESPACE     NAME                                 DATA   AGE
kube-public   cluster-info                         2      174m
kube-system   coredns                              1      174m
kube-system   extension-apiserver-authentication   6      174m
kube-system   flannel-plugin-config-map            2      174m
kube-system   kube-proxy                           2      174m
kube-system   kubeadm-config                       2      174m
kube-system   kubelet-config-1.13                  1      174m
kube-system   kubic-init-config-seeder             1      174m
$
$
$ kubectl version
Client Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"archive", BuildDate:"2018-12-07T12:00:00Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"13", GitVersion:"v1.13.0", GitCommit:"ddf47ac13c1a9483ea035a79cd7c10005ff21a6d", GitTreeState:"clean", BuildDate:"2018-12-03T20:56:12Z", GoVersion:"go1.11.2", Compiler:"gc", Platform:"linux/amd64"}

On the node:

$ cat config.txt 
apiVersion: kubeadm.k8s.io/v1beta1
caCertPath: /etc/kubernetes/pki/ca.crt
discovery:
  bootstrapToken:
    apiServerEndpoint: 192.168.100.1:6443
    token: 94dcda.c271f4ff502789ca
    unsafeSkipCAVerification: true
  timeout: 5m0s
  tlsBootstrapToken: 94dcda.c271f4ff502789ca
kind: JoinConfiguration
nodeRegistration:
  criSocket: /var/run/crio/crio.sock
  kubeletExtraArgs:
    cni-bin-dir: /var/lib/kubelet/cni/bin
    cni-conf-dir: /etc/cni/net.d
    container-runtime-endpoint: unix:///var/run/crio/crio.sock
    network-plugin: cni

$
$ kubeadm join --v=8 --config=config.txt 
I1220 11:55:56.879023       7 join.go:299] [join] found NodeName empty; using OS hostname as NodeName
I1220 11:55:56.880357       7 joinconfiguration.go:72] loading configuration from the given file
[preflight] Running pre-flight checks
I1220 11:55:56.890498       7 join.go:328] [preflight] Running general checks
I1220 11:55:56.891937       7 checks.go:245] validating the existence and emptiness of directory /etc/kubernetes/manifests
I1220 11:55:56.893051       7 checks.go:283] validating the existence of file /etc/kubernetes/kubelet.conf
I1220 11:55:56.894239       7 checks.go:283] validating the existence of file /etc/kubernetes/bootstrap-kubelet.conf
I1220 11:55:56.895384       7 checks.go:104] validating the container runtime
I1220 11:55:57.072517       7 checks.go:373] validating the presence of executable crictl
I1220 11:55:57.073553       7 checks.go:332] validating the contents of file /proc/sys/net/bridge/bridge-nf-call-iptables
I1220 11:55:57.074479       7 checks.go:332] validating the contents of file /proc/sys/net/ipv4/ip_forward
I1220 11:55:57.075518       7 checks.go:644] validating whether swap is enabled or not
I1220 11:55:57.076499       7 checks.go:373] validating the presence of executable ip
I1220 11:55:57.077424       7 checks.go:373] validating the presence of executable iptables
I1220 11:55:57.078594       7 checks.go:373] validating the presence of executable mount
I1220 11:55:57.079564       7 checks.go:373] validating the presence of executable nsenter
I1220 11:55:57.080425       7 checks.go:373] validating the presence of executable ebtables
I1220 11:55:57.081391       7 checks.go:373] validating the presence of executable ethtool
I1220 11:55:57.082170       7 checks.go:373] validating the presence of executable socat
I1220 11:55:57.084207       7 checks.go:373] validating the presence of executable tc
I1220 11:55:57.085250       7 checks.go:373] validating the presence of executable touch
I1220 11:55:57.086132       7 checks.go:515] running all checks
I1220 11:55:57.137681       7 checks.go:403] checking whether the given node name is reachable using net.LookupHost
I1220 11:55:57.150619       7 checks.go:613] validating kubelet version
I1220 11:55:57.450319       7 checks.go:130] validating if the service is enabled and active
I1220 11:55:57.554984       7 checks.go:208] validating availability of port 10250
I1220 11:55:57.556700       7 checks.go:283] validating the existence of file /etc/kubernetes/pki/ca.crt
I1220 11:55:57.557579       7 checks.go:430] validating if the connectivity type is via proxy or direct
[preflight] Some fatal errors occurred:
    [ERROR FileAvailable--etc-kubernetes-bootstrap-kubelet.conf]: /etc/kubernetes/bootstrap-kubelet.conf already exists
    [ERROR FileAvailable--etc-kubernetes-pki-ca.crt]: /etc/kubernetes/pki/ca.crt already exists
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
sh-4.4# rm -f /etc/kubernetes/bootstrap-kubelet.conf /etc/kubernetes/pki/ca.crt
sh-4.4# kubeadm join --v=8 --config=config.txt 
I1220 11:56:10.073469      30 join.go:299] [join] found NodeName empty; using OS hostname as NodeName
I1220 11:56:10.074575      30 joinconfiguration.go:72] loading configuration from the given file
[preflight] Running pre-flight checks
I1220 11:56:10.085937      30 join.go:328] [preflight] Running general checks
I1220 11:56:10.086871      30 checks.go:245] validating the existence and emptiness of directory /etc/kubernetes/manifests
I1220 11:56:10.087809      30 checks.go:283] validating the existence of file /etc/kubernetes/kubelet.conf
I1220 11:56:10.088573      30 checks.go:283] validating the existence of file /etc/kubernetes/bootstrap-kubelet.conf
I1220 11:56:10.089370      30 checks.go:104] validating the container runtime
I1220 11:56:10.126939      30 checks.go:373] validating the presence of executable crictl
I1220 11:56:10.128075      30 checks.go:332] validating the contents of file /proc/sys/net/bridge/bridge-nf-call-iptables
I1220 11:56:10.129096      30 checks.go:332] validating the contents of file /proc/sys/net/ipv4/ip_forward
I1220 11:56:10.129993      30 checks.go:644] validating whether swap is enabled or not
I1220 11:56:10.131006      30 checks.go:373] validating the presence of executable ip
I1220 11:56:10.132983      30 checks.go:373] validating the presence of executable iptables
I1220 11:56:10.139740      30 checks.go:373] validating the presence of executable mount
I1220 11:56:10.140267      30 checks.go:373] validating the presence of executable nsenter
I1220 11:56:10.140738      30 checks.go:373] validating the presence of executable ebtables
I1220 11:56:10.141092      30 checks.go:373] validating the presence of executable ethtool
I1220 11:56:10.141459      30 checks.go:373] validating the presence of executable socat
I1220 11:56:10.142799      30 checks.go:373] validating the presence of executable tc
I1220 11:56:10.145062      30 checks.go:373] validating the presence of executable touch
I1220 11:56:10.145954      30 checks.go:515] running all checks
I1220 11:56:10.189173      30 checks.go:403] checking whether the given node name is reachable using net.LookupHost
I1220 11:56:10.204103      30 checks.go:613] validating kubelet version
I1220 11:56:10.529594      30 checks.go:130] validating if the service is enabled and active
I1220 11:56:10.556043      30 checks.go:208] validating availability of port 10250
I1220 11:56:10.557915      30 checks.go:283] validating the existence of file /etc/kubernetes/pki/ca.crt
I1220 11:56:10.559380      30 checks.go:430] validating if the connectivity type is via proxy or direct
I1220 11:56:10.560242      30 join.go:334] [preflight] Fetching init configuration
I1220 11:56:10.561013      30 join.go:601] [join] Discovering cluster-info
[discovery] Trying to connect to API Server "192.168.100.1:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.100.1:6443"
I1220 11:56:10.567171      30 round_trippers.go:383] GET https://192.168.100.1:6443/api/v1/namespaces/kube-public/configmaps/cluster-info
I1220 11:56:10.568131      30 round_trippers.go:390] Request Headers:
I1220 11:56:10.568891      30 round_trippers.go:393]     Accept: application/json, */*
I1220 11:56:10.569609      30 round_trippers.go:393]     User-Agent: kubeadm/v1.13.0 (linux/amd64) kubernetes/ddf47ac
I1220 11:56:10.586461      30 round_trippers.go:408] Response Status: 200 OK in 16 milliseconds
I1220 11:56:10.587241      30 round_trippers.go:411] Response Headers:
I1220 11:56:10.588006      30 round_trippers.go:414]     Content-Type: application/json
I1220 11:56:10.588757      30 round_trippers.go:414]     Content-Length: 1991
I1220 11:56:10.589497      30 round_trippers.go:414]     Date: Thu, 20 Dec 2018 11:56:11 GMT
I1220 11:56:10.590141      30 request.go:942] Response Body: {"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"cluster-info","namespace":"kube-public","selfLink":"/api/v1/namespaces/kube-public/configmaps/cluster-info","uid":"c8b93b6b-0436-11e9-b4e4-4845202d6379","resourceVersion":"368","creationTimestamp":"2018-12-20T09:08:15Z"},"data":{"jws-kubeconfig-94dcda":"eyJhbGciOiJIUzI1NiIsImtpZCI6Ijk0ZGNkYSJ9..qJePAaUQp5APwTC-dSSzvL3MEVE8PQxgbvipbsC1faA","kubeconfig":"apiVersion: v1\nclusters:\n- cluster:\n    certificate-authority-data: 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 [truncated 967 chars]
[discovery] Cluster info signature and contents are valid and no TLS pinning was specified, will use API Server "192.168.100.1:6443"
[discovery] Successfully established connection with API Server "192.168.100.1:6443"
I1220 11:56:10.596836      30 join.go:608] [join] Retrieving KubeConfig objects
[join] Reading configuration from the cluster...
[join] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
I1220 11:56:10.600835      30 round_trippers.go:383] GET https://192.168.100.1:6443/api/v1/namespaces/kube-system/configmaps/kubeadm-config
I1220 11:56:10.601554      30 round_trippers.go:390] Request Headers:
I1220 11:56:10.602287      30 round_trippers.go:393]     User-Agent: kubeadm/v1.13.0 (linux/amd64) kubernetes/ddf47ac
I1220 11:56:10.603124      30 round_trippers.go:393]     Accept: application/json, */*
I1220 11:56:10.603831      30 round_trippers.go:393]     Authorization: Bearer 94dcda.c271f4ff502789ca
I1220 11:56:10.633321      30 round_trippers.go:408] Response Status: 200 OK in 28 milliseconds
I1220 11:56:10.634283      30 round_trippers.go:411] Response Headers:
I1220 11:56:10.635127      30 round_trippers.go:414]     Date: Thu, 20 Dec 2018 11:56:11 GMT
I1220 11:56:10.635912      30 round_trippers.go:414]     Content-Type: application/json
I1220 11:56:10.636635      30 round_trippers.go:414]     Content-Length: 1316
I1220 11:56:10.637413      30 request.go:942] Response Body: {"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"kubeadm-config","namespace":"kube-system","selfLink":"/api/v1/namespaces/kube-system/configmaps/kubeadm-config","uid":"c8069fb3-0436-11e9-b4e4-4845202d6379","resourceVersion":"173","creationTimestamp":"2018-12-20T09:08:14Z"},"data":{"ClusterConfiguration":"apiServer:\n  certSANs:\n  - 192.168.100.1\n  extraArgs:\n    authorization-mode: Node,RBAC\n    oidc-ca-file: /etc/kubernetes/pki/ca.crt\n    oidc-client-id: kubernetes\n    oidc-groups-claim: group\n    oidc-issuer-url: https://192.168.0.154:32000\n    oidc-username-claim: email\n  timeoutForControlPlane: 4m0s\napiVersion: kubeadm.k8s.io/v1beta1\ncertificatesDir: /etc/kubernetes/pki\nclusterName: kubernetes\ncontrolPlaneEndpoint: \"\"\ncontrollerManager: {}\ndns:\n  type: CoreDNS\netcd:\n  local:\n    dataDir: /var/lib/etcd\n    imageRepository: registry.opensuse.org/devel/kubic/containers/container/kubic\n    imageTag: \"3.3\"\nimageRepository: k8s.gcr.io\nkind: ClusterConfiguration\nkubernetesVer [truncated 292 chars]
I1220 11:56:10.643565      30 round_trippers.go:383] GET https://192.168.100.1:6443/api/v1/namespaces/kube-system/configmaps/kube-proxy
I1220 11:56:10.644430      30 round_trippers.go:390] Request Headers:
I1220 11:56:10.645126      30 round_trippers.go:393]     Accept: application/json, */*
I1220 11:56:10.645791      30 round_trippers.go:393]     User-Agent: kubeadm/v1.13.0 (linux/amd64) kubernetes/ddf47ac
I1220 11:56:10.646455      30 round_trippers.go:393]     Authorization: Bearer 94dcda.c271f4ff502789ca
I1220 11:56:10.654053      30 round_trippers.go:408] Response Status: 200 OK in 6 milliseconds
I1220 11:56:10.655099      30 round_trippers.go:411] Response Headers:
I1220 11:56:10.655921      30 round_trippers.go:414]     Content-Type: application/json
I1220 11:56:10.656796      30 round_trippers.go:414]     Content-Length: 1655
I1220 11:56:10.657597      30 round_trippers.go:414]     Date: Thu, 20 Dec 2018 11:56:11 GMT
I1220 11:56:10.658883      30 request.go:942] Response Body: {"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"kube-proxy","namespace":"kube-system","selfLink":"/api/v1/namespaces/kube-system/configmaps/kube-proxy","uid":"c8de0370-0436-11e9-b4e4-4845202d6379","resourceVersion":"229","creationTimestamp":"2018-12-20T09:08:15Z","labels":{"app":"kube-proxy"}},"data":{"config.conf":"apiVersion: kubeproxy.config.k8s.io/v1alpha1\nbindAddress: 0.0.0.0\nclientConnection:\n  acceptContentTypes: \"\"\n  burst: 10\n  contentType: application/vnd.kubernetes.protobuf\n  kubeconfig: /var/lib/kube-proxy/kubeconfig.conf\n  qps: 5\nclusterCIDR: 172.16.0.0/13\nconfigSyncPeriod: 15m0s\nconntrack:\n  max: null\n  maxPerCore: 32768\n  min: 131072\n  tcpCloseWaitTimeout: 1h0m0s\n  tcpEstablishedTimeout: 24h0m0s\nenableProfiling: false\nhealthzBindAddress: 0.0.0.0:10256\nhostnameOverride: \"\"\niptables:\n  masqueradeAll: false\n  masqueradeBit: 14\n  minSyncPeriod: 0s\n  syncPeriod: 30s\nipvs:\n  excludeCIDRs: null\n  minSyncPeriod: 0s\n  scheduler: \"\"\n  syncPeriod: 30s\nkind: Kub [truncated 631 chars]
I1220 11:56:10.664746      30 round_trippers.go:383] GET https://192.168.100.1:6443/api/v1/namespaces/kube-system/configmaps/kubelet-config-1.13
I1220 11:56:10.665883      30 round_trippers.go:390] Request Headers:
I1220 11:56:10.666731      30 round_trippers.go:393]     User-Agent: kubeadm/v1.13.0 (linux/amd64) kubernetes/ddf47ac
I1220 11:56:10.667616      30 round_trippers.go:393]     Authorization: Bearer 94dcda.c271f4ff502789ca
I1220 11:56:10.668451      30 round_trippers.go:393]     Accept: application/json, */*
I1220 11:56:10.676896      30 round_trippers.go:408] Response Status: 200 OK in 7 milliseconds
I1220 11:56:10.677820      30 round_trippers.go:411] Response Headers:
I1220 11:56:10.680010      30 round_trippers.go:414]     Content-Type: application/json
I1220 11:56:10.681115      30 round_trippers.go:414]     Content-Length: 2134
I1220 11:56:10.682015      30 round_trippers.go:414]     Date: Thu, 20 Dec 2018 11:56:11 GMT
I1220 11:56:10.683204      30 request.go:942] Response Body: {"kind":"ConfigMap","apiVersion":"v1","metadata":{"name":"kubelet-config-1.13","namespace":"kube-system","selfLink":"/api/v1/namespaces/kube-system/configmaps/kubelet-config-1.13","uid":"c80c1601-0436-11e9-b4e4-4845202d6379","resourceVersion":"176","creationTimestamp":"2018-12-20T09:08:14Z"},"data":{"kubelet":"address: 0.0.0.0\napiVersion: kubelet.config.k8s.io/v1beta1\nauthentication:\n  anonymous:\n    enabled: false\n  webhook:\n    cacheTTL: 2m0s\n    enabled: true\n  x509:\n    clientCAFile: /etc/kubernetes/pki/ca.crt\nauthorization:\n  mode: Webhook\n  webhook:\n    cacheAuthorizedTTL: 5m0s\n    cacheUnauthorizedTTL: 30s\ncgroupDriver: cgroupfs\ncgroupsPerQOS: true\nclusterDNS:\n- 172.24.0.10\nclusterDomain: cluster.local\nconfigMapAndSecretChangeDetectionStrategy: Watch\ncontainerLogMaxFiles: 5\ncontainerLogMaxSize: 10Mi\ncontentType: application/vnd.kubernetes.protobuf\ncpuCFSQuota: true\ncpuCFSQuotaPeriod: 100ms\ncpuManagerPolicy: none\ncpuManagerReconcilePeriod: 10s\nenableControllerAttachDetach: tr [truncated 1110 chars]
I1220 11:56:10.688139      30 interface.go:384] Looking for default routes with IPv4 addresses
I1220 11:56:10.688797      30 interface.go:389] Default route transits interface "eth0"
I1220 11:56:10.689612      30 interface.go:196] Interface eth0 is up
I1220 11:56:10.690375      30 interface.go:244] Interface "eth0" has 2 addresses :[192.168.100.220/24 fe80::d0a8:62ff:fe54:b6e9/64].
I1220 11:56:10.690995      30 interface.go:211] Checking addr  192.168.100.220/24.
I1220 11:56:10.691796      30 interface.go:218] IP found 192.168.100.220
I1220 11:56:10.692489      30 interface.go:250] Found valid IPv4 address 192.168.100.220 for interface "eth0".
I1220 11:56:10.693168      30 interface.go:395] Found active IP 192.168.100.220 
I1220 11:56:10.694393      30 join.go:341] [preflight] Running configuration dependant checks
I1220 11:56:10.695211      30 join.go:478] [join] writing bootstrap kubelet config file at /etc/kubernetes/bootstrap-kubelet.conf
I1220 11:56:10.942159      30 loader.go:359] Config loaded from file /etc/kubernetes/bootstrap-kubelet.conf
I1220 11:56:10.943961      30 join.go:503] Stopping the kubelet
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.12" ConfigMap in the kube-system namespace
I1220 11:56:10.977300      30 round_trippers.go:383] GET https://192.168.100.1:6443/api/v1/namespaces/kube-system/configmaps/kubelet-config-1.12
I1220 11:56:10.978035      30 round_trippers.go:390] Request Headers:
I1220 11:56:10.978844      30 round_trippers.go:393]     User-Agent: kubeadm/v1.13.0 (linux/amd64) kubernetes/ddf47ac
I1220 11:56:10.979502      30 round_trippers.go:393]     Accept: application/json, */*
I1220 11:56:10.980081      30 round_trippers.go:393]     Authorization: Bearer 94dcda.c271f4ff502789ca
I1220 11:56:10.983223      30 round_trippers.go:408] Response Status: 403 Forbidden in 2 milliseconds
I1220 11:56:10.984240      30 round_trippers.go:411] Response Headers:
I1220 11:56:10.985065      30 round_trippers.go:414]     Content-Type: application/json
I1220 11:56:10.985883      30 round_trippers.go:414]     X-Content-Type-Options: nosniff
I1220 11:56:10.987515      30 round_trippers.go:414]     Content-Length: 342
I1220 11:56:10.989207      30 round_trippers.go:414]     Date: Thu, 20 Dec 2018 11:56:11 GMT
I1220 11:56:10.990506      30 request.go:942] Response Body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"configmaps \"kubelet-config-1.12\" is forbidden: User \"system:bootstrap:94dcda\" cannot get resource \"configmaps\" in API group \"\" in the namespace \"kube-system\"","reason":"Forbidden","details":{"name":"kubelet-config-1.12","kind":"configmaps"},"code":403}
configmaps "kubelet-config-1.12" is forbidden: User "system:bootstrap:94dcda" cannot get resource "configmaps" in API group "" in the namespace "kube-system"
$
$
$ kubeadm version -o json
{
  "clientVersion": {
    "major": "1",
    "minor": "13",
    "gitVersion": "v1.13.0",
    "gitCommit": "ddf47ac13c1a9483ea035a79cd7c10005ff21a6d",
    "gitTreeState": "archive",
    "buildDate": "2018-12-07T12:00:00Z",
    "goVersion": "go1.11.2",
    "compiler": "gc",
    "platform": "linux/amd64"
  }
}

For some reason it seems it is looking for kubelet-config-1.12 while the right ConfigMap should be kubelet-config-1.13.

After checking the kubelet --version I see that:

$ kubelet --version
Kubernetes v1.12.0

Is the configmap name derived from this?

inercia picture inercia on 20 Dec 2018

@inercia the configmap name is derived from the kubelet version. See my link above.

oz123 picture oz123 on 20 Dec 2018

Thanks for the clarification @oz123.

I was wondering what would happen on updates. For example,

1) a seeder is installed with my-distribution-1.13 that includes kubeadm-1.13
2) the seeder is initialized
3) some time after that, a node is installed with the same distro, installing the kubeadm-1.13 and kubelet-1.13
4) but some updates are applied at the end of the installation, and the new kubelet-1.14 is installed
5) the kubeadm join tries to look for the configmap for 1.14 but it is not there...

inercia picture inercia on 20 Dec 2018

I'm seeing this issue installing k8s 1.13.1 with a matching kubeadm version, but isolated to kube-proxy:

kubeadm join --config /etc/kubernetes/kubeadm-client.conf --ignore-preflight-errors=all
[preflight] Running pre-flight checks
[discovery] Trying to connect to API Server "xxx.xxx.xxx.xxx:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://xxx.xxx.xxx.xxx:6443"
[discovery] Cluster info signature and contents are valid and no TLS pinning was specified, will use API Server "xxx.xxx.xxx.xxx:6443"
[discovery] Successfully established connection with API Server "xxx.xxx.xxx.xxx:6443"
[join] Reading configuration from the cluster...
[join] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
unable to fetch the kubeadm-config ConfigMap: failed to get component configs: configmaps "kube-proxy" is forbidden: User "system:bootstrap:3tw24k" cannot get resource "configmaps" in API group "" in the namespace "kube-system"

If I create a workaround RoleBinding manually, I'm able to join nodes.

# on controlplane node
kubectl create rolebinding -n kube-system --role kube-proxy --group system:bootstrappers:kubeadm:default-node-token kubeadm:kube-proxy-bootstrap

# on joining node
...
[join] Reading configuration from the cluster...
[join] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet] Downloading configuration for the kubelet from the "kubelet-config-1.13" ConfigMap in the kube-system namespace
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Activating the kubelet service
[tlsbootstrap] Waiting for the kubelet to perform the TLS Bootstrap...
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "ci-pdk1-debug4144-k8sne-1" as an annotation

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the master to see this node join the cluster.

Is a kube-proxy RoleBinding for the system:bootstrappers:kubeadm:default-node-token Group supposed to populate automatically? Any idea what's going on here?

EDIT: Also found that running kubeadm init phase addon kube-proxy explicitly after my first kubeadm init creates a kube-proxy RoleBinding for system:bootstrappers:kubeadm:default-node-token. Still not sure why my initial kubeadm init skips creating this RoleBinding.

chadswen picture chadswen on 9 Jan 2019

This worked for me:

Definitely check your version of kubeadm and kubelet, make sure the same version of these packages is used along all of your nodes. Prior to installing, you should "mark and hold" your versions of these on your hosts:

check your current version of each:
kubelet --version

check kubeadm
kubeadm version

if they're different, you've got problems. You should reinstall the same version among all your nodes and allow downgrades. My versions in the command below are probably older than what is currently out, you can replace the version number with some more up to date, but this will work:
sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu kubelet=1.12.2-00 kubeadm=1.12.2-00 kubectl=1.12.2-00 --allow-downgrades

then, once they're installed, mark and hold them so they can't be upgraded automatically, and break your system
sudo apt-mark hold docker-ce kubelet kubeadm kubectl

texasdave2 picture texasdave2 on 3 Mar 2019
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