Troubleshooting Control Plane
This guide is written as series of topics and detailed answers for each topic. It starts with basics of control plane and goes into Talos specifics.
In this guide we assume that Talos client config is available and Talos API access is available.
Kubernetes client configuration can be pulled from control plane nodes with
talosctl -n <IP> kubeconfig
(this command works before Kubernetes is fully booted).
What is a control plane node?
Talos nodes which have
controlplane are control plane nodes.
The only difference between
controlplane nodes is that
init node automatically
bootstraps a single-node
etcd cluster on a first boot if the etcd data directory is empty.
A node with type
init can be replaced with a
controlplane node which is triggered to run etcd bootstrap
talosctl --nodes <IP> bootstrap command.
init type nodes is discouraged, as it might lead to split-brain scenario if one node in
existing cluster is reinstalled while config type is still
It is critical to make sure only one control plane runs in bootstrap mode (either with node type
via bootstrap API/
talosctl bootstrap), as having more than node in bootstrap mode leads to split-brain
scenario (multiple etcd clusters are built instead of a single cluster).
What is special about control plane node?
Control plane nodes in Talos run
etcd which provides data store for Kubernetes and Kubernetes control plane
Control plane nodes are tainted by default to prevent workloads from being scheduled to control plane nodes.
How many control plane nodes should be deployed?
With a single control plane node, cluster is not HA: if that single node experiences hardware failure, cluster control plane is broken and can’t be recovered. Single control plane node clusters are still used as test clusters and in edge deployments, but it should be noted that this setup is not HA.
Number of control plane should be odd (1, 3, 5, …), as with even number of nodes, etcd quorum doesn’t tolerate failures correctly: e.g. with 2 control plane nodes quorum is 2, so failure of any node breaks quorum, so this setup is almost equivalent to single control plane node cluster.
With three control plane nodes cluster can tolerate a failure of any single control plane node. With five control plane nodes cluster can tolerate failure of any two control plane nodes.
What is control plane endpoint?
Kubernetes requires having a control plane endpoint which points to any healthy API server running on a control plane node.
Control plane endpoint is specified as URL like
At any point in time, even during failures control plane endpoint should point to a healthy API server instance.
kube-apiserver runs with host network, control plane endpoint should point to one of the control plane node IPs:
For single control plane node clusters, control plane endpoint might be
IP is the IP of the control plane node and
DNS points to
DNS form of the endpoint allows to change the IP address of the control plane if that IP changes over time.
For HA clusters, control plane can be implemented as:
- TCP L7 loadbalancer with active health checks against port 6443
- round-robin DNS with active health checks against port 6443
- BGP anycast IP with health checks
- virtual shared L2 IP
It is critical that control plane endpoint works correctly during cluster bootstrap phase, as nodes discover each other using control plane endpoint.
kubelet is not running on control plane node
kubelet should be running on control plane node as soon as networking is configured:
$ talosctl -n <IP> service kubelet NODE 172.20.0.2 ID kubelet STATE Running HEALTH OK EVENTS [Running]: Health check successful (2m54s ago) [Running]: Health check failed: Get "http://127.0.0.1:10248/healthz": dial tcp 127.0.0.1:10248: connect: connection refused (3m4s ago) [Running]: Started task kubelet (PID 2334) for container kubelet (3m6s ago) [Preparing]: Creating service runner (3m6s ago) [Preparing]: Running pre state (3m15s ago) [Waiting]: Waiting for service "timed" to be "up" (3m15s ago) [Waiting]: Waiting for service "cri" to be "up", service "timed" to be "up" (3m16s ago) [Waiting]: Waiting for service "cri" to be "up", service "networkd" to be "up", service "timed" to be "up" (3m18s ago)
kubelet is not running, it might be caused by wrong configuration, check
$ talosctl -n <IP> logs kubelet 172.20.0.2: I0305 20:45:07.756948 2334 controller.go:101] kubelet config controller: starting controller 172.20.0.2: I0305 20:45:07.756995 2334 controller.go:267] kubelet config controller: ensuring filesystem is set up correctly 172.20.0.2: I0305 20:45:07.757000 2334 fsstore.go:59] kubelet config controller: initializing config checkpoints directory "/etc/kubernetes/kubelet/store"
etcd is not running on bootstrap node
etcd should be running on bootstrap node immediately (bootstrap node is either
init node or
talosctl bootstrap command was issued).
When node boots for the first time,
etcd data directory
/var/lib/etcd directory is empty and Talos launches
etcd in a mode to build the initial cluster of a single node.
At this time
/var/lib/etcd directory becomes non-empty and
etcd runs as usual.
etcd is not running, check service
$ talosctl -n <IP> service etcd NODE 172.20.0.2 ID etcd STATE Running HEALTH OK EVENTS [Running]: Health check successful (3m21s ago) [Running]: Started task etcd (PID 2343) for container etcd (3m26s ago) [Preparing]: Creating service runner (3m26s ago) [Preparing]: Running pre state (3m26s ago) [Waiting]: Waiting for service "cri" to be "up", service "networkd" to be "up", service "timed" to be "up" (3m26s ago)
If service is stuck in
Preparing state for bootstrap node, it might be related to slow network - at this stage
etcd image from the container registry.
etcd service is crashing and restarting, check service logs with
talosctl -n <IP> logs etcd.
Most common reasons for crashes are:
- wrong arguments passed via
extraArgsin the configuration;
- booting Talos on non-empty disk with previous Talos installation,
/var/lib/etcdcontains data from old cluster.
etcd is not running on non-bootstrap control plane node
etcd on non-bootstrap control plane node waits for Kubernetes to boot successfully on bootstrap node to find
other peers to build a cluster.
As soon as bootstrap node boots Kubernetes control plane components, and
kubectl get endpoints returns IP of bootstrap control plane node, other control plane nodes will start joining the cluster followed by Kubernetes control plane components on each control plane node.
Kubernetes static pod definitions are not generated
Talos should write down static pod definitions for the Kubernetes control plane:
$ talosctl -n <IP> ls /etc/kubernetes/manifests NODE NAME 172.20.0.2 . 172.20.0.2 talos-kube-apiserver.yaml 172.20.0.2 talos-kube-controller-manager.yaml 172.20.0.2 talos-kube-scheduler.yaml
If static pod definitions are not rendered, check
kubelet service health (see above),
and controller runtime logs (
talosctl logs controller-runtime).
Talos prints error
an error on the server ("") has prevented the request from succeeding
This is expected during initial cluster bootstrap and sometimes after a reboot:
[ 70.093289] [talos] task labelNodeAsMaster (1/1): starting [ 80.094038] [talos] retrying error: an error on the server ("") has prevented the request from succeeding (get nodes talos-default-master-1)
kube-apiserver component is not running yet, and it takes some time before it becomes fully up
during bootstrap (image should be pulled from the Internet, etc.)
Once control plane endpoint is up Talos should proceed.
If Talos doesn’t proceed further, it might be a configuration issue.
In any case, status of control plane components can be checked with
talosctl containers -k:
$ talosctl -n <IP> containers --kubernetes NODE NAMESPACE ID IMAGE PID STATUS 172.20.0.2 k8s.io kube-system/kube-apiserver-talos-default-master-1 k8s.gcr.io/pause:3.2 2539 SANDBOX_READY 172.20.0.2 k8s.io └─ kube-system/kube-apiserver-talos-default-master-1:kube-apiserver k8s.gcr.io/kube-apiserver:v1.20.4 2572 CONTAINER_RUNNING
kube-apiserver shows as
CONTAINER_EXITED, it might have exited due to configuration error.
Logs can be checked with
taloctl logs --kubernetes (or with
-k as a shorthand):
$ talosctl -n <IP> logs -k kube-system/kube-apiserver-talos-default-master-1:kube-apiserver 172.20.0.2: 2021-03-05T20:46:13.133902064Z stderr F 2021/03/05 20:46:13 Running command: 172.20.0.2: 2021-03-05T20:46:13.133933824Z stderr F Command env: (log-file=, also-stdout=false, redirect-stderr=true) 172.20.0.2: 2021-03-05T20:46:13.133938524Z stderr F Run from directory: 172.20.0.2: 2021-03-05T20:46:13.13394154Z stderr F Executable path: /usr/local/bin/kube-apiserver ...
Talos prints error
nodes "talos-default-master-1" not found
This error means that
kube-apiserver is up, and control plane endpoint is healthy, but
kubelet hasn’t got
its client certificate yet and wasn’t able to register itself.
kubelet to get its client certificate, following conditions should apply:
- control plane endpoint is healthy (
- bootstrap manifests got successfully deployed (for CSR auto-approval)
CSR state can be checked with
kubectl get csr:
$ kubectl get csr NAME AGE SIGNERNAME REQUESTOR CONDITION csr-jcn9j 14m kubernetes.io/kube-apiserver-client-kubelet system:bootstrap:q9pyzr Approved,Issued csr-p6b9q 14m kubernetes.io/kube-apiserver-client-kubelet system:bootstrap:q9pyzr Approved,Issued csr-sw6rm 14m kubernetes.io/kube-apiserver-client-kubelet system:bootstrap:q9pyzr Approved,Issued csr-vlghg 14m kubernetes.io/kube-apiserver-client-kubelet system:bootstrap:q9pyzr Approved,Issued
Talos prints error
node not ready
Node in Kubernetes is marked as
Ready once CNI is up.
It takes a minute or two for the CNI images to be pulled and for the CNI to start.
If the node is stuck in this state for too long, check CNI pods and logs with
CNI resources are created in
For example, for Talos default Flannel CNI:
$ kubectl -n kube-system get pods NAME READY STATUS RESTARTS AGE ... kube-flannel-25drx 1/1 Running 0 23m kube-flannel-8lmb6 1/1 Running 0 23m kube-flannel-gl7nx 1/1 Running 0 23m kube-flannel-jknt9 1/1 Running 0 23m ...
Talos prints error
x509: certificate signed by unknown authority
Full error might look like:
x509: certificate signed by unknown authority (possiby because of crypto/rsa: verification error" while trying to verify candidate authority certificate "kubernetes"
Commonly, the control plane endpoint points to a different cluster, as the client certificate generated by Talos doesn’t match CA of the cluster at control plane endpoint.
etcd is running on bootstrap node, but stuck in
pre state on non-bootstrap nodes
Please see question
etcd is not running on non-bootstrap control plane node.
If control plane endpoint is up, status of the pods can be performed with
$ kubectl get pods -n kube-system -l k8s-app=kube-controller-manager NAME READY STATUS RESTARTS AGE kube-controller-manager-talos-default-master-1 1/1 Running 0 28m kube-controller-manager-talos-default-master-2 1/1 Running 0 28m kube-controller-manager-talos-default-master-3 1/1 Running 0 28m
If control plane endpoint is not up yet, container status can be queried with
talosctl containers --kubernetes:
$ talosctl -n <IP> c -k NODE NAMESPACE ID IMAGE PID STATUS ... 172.20.0.2 k8s.io kube-system/kube-controller-manager-talos-default-master-1 k8s.gcr.io/pause:3.2 2547 SANDBOX_READY 172.20.0.2 k8s.io └─ kube-system/kube-controller-manager-talos-default-master-1:kube-controller-manager k8s.gcr.io/kube-controller-manager:v1.20.4 2580 CONTAINER_RUNNING 172.20.0.2 k8s.io kube-system/kube-scheduler-talos-default-master-1 k8s.gcr.io/pause:3.2 2638 SANDBOX_READY 172.20.0.2 k8s.io └─ kube-system/kube-scheduler-talos-default-master-1:kube-scheduler k8s.gcr.io/kube-scheduler:v1.20.4 2670 CONTAINER_RUNNING ...
If some of the containers are not running, it could be that image is still being pulled.
Otherwise process might crashing, in that case logs can be checked with
talosctl logs --kubernetes <containerID>:
$ talosctl -n <IP> logs -k kube-system/kube-controller-manager-talos-default-master-1:kube-controller-manager 172.20.0.3: 2021-03-09T13:59:34.291667526Z stderr F 2021/03/09 13:59:34 Running command: 172.20.0.3: 2021-03-09T13:59:34.291702262Z stderr F Command env: (log-file=, also-stdout=false, redirect-stderr=true) 172.20.0.3: 2021-03-09T13:59:34.291707121Z stderr F Run from directory: 172.20.0.3: 2021-03-09T13:59:34.291710908Z stderr F Executable path: /usr/local/bin/kube-controller-manager 172.20.0.3: 2021-03-09T13:59:34.291719163Z stderr F Args (comma-delimited): /usr/local/bin/kube-controller-manager,--allocate-node-cidrs=true,--cloud-provider=,--cluster-cidr=10.244.0.0/16,--service-cluster-ip-range=10.96.0.0/12,--cluster-signing-cert-file=/system/secrets/kubernetes/kube-controller-manager/ca.crt,--cluster-signing-key-file=/system/secrets/kubernetes/kube-controller-manager/ca.key,--configure-cloud-routes=false,--kubeconfig=/system/secrets/kubernetes/kube-controller-manager/kubeconfig,--leader-elect=true,--root-ca-file=/system/secrets/kubernetes/kube-controller-manager/ca.crt,--service-account-private-key-file=/system/secrets/kubernetes/kube-controller-manager/service-account.key,--profiling=false 172.20.0.3: 2021-03-09T13:59:34.293870359Z stderr F 2021/03/09 13:59:34 Now listening for interrupts 172.20.0.3: 2021-03-09T13:59:34.761113762Z stdout F I0309 13:59:34.760982 10 serving.go:331] Generated self-signed cert in-memory ...
Checking controller runtime logs
Talos runs a set of controllers which work on resources to build and support Kubernetes control plane.
Some debugging information can be queried from the controller logs with
talosctl logs controller-runtime:
$ talosctl -n <IP> logs controller-runtime 172.20.0.2: 2021/03/09 13:57:11 secrets.EtcdController: controller starting 172.20.0.2: 2021/03/09 13:57:11 config.MachineTypeController: controller starting 172.20.0.2: 2021/03/09 13:57:11 k8s.ManifestApplyController: controller starting 172.20.0.2: 2021/03/09 13:57:11 v1alpha1.BootstrapStatusController: controller starting 172.20.0.2: 2021/03/09 13:57:11 v1alpha1.TimeStatusController: controller starting ...
Controllers run reconcile loop, so they might be starting, failing and restarting, that is expected behavior. Things to look for:
v1alpha1.BootstrapStatusController: bootkube initialized status not found: control plane is not self-hosted, running with static pods.
k8s.KubeletStaticPodController: writing static pod "/etc/kubernetes/manifests/talos-kube-apiserver.yaml": static pod definitions were rendered successfully.
k8s.ManifestApplyController: controller failed: error creating mapping for object /v1/Secret/bootstrap-token-q9pyzr: an error on the server ("") has prevented the request from succeeding: control plane endpoint is not up yet, bootstrap manifests can’t be injected, controller is going to retry.
k8s.KubeletStaticPodController: controller failed: error refreshing pod status: error fetching pod status: an error on the server ("Authorization error (user=apiserver-kubelet-client, verb=get, resource=nodes, subresource=proxy)") has prevented the request from succeeding: kubelet hasn’t been able to contact
kube-apiserver yet to push pod status, controller
is going to retry.
k8s.ManifestApplyController: created rbac.authorization.k8s.io/v1/ClusterRole/psp:privileged: one of the bootstrap manifests got successfully applied.
secrets.KubernetesController: controller failed: missing cluster.aggregatorCA secret: Talos is running with 0.8 configuration, if the cluster was upgraded from 0.8, this is expected, and conversion process will fix machine config
If this cluster was bootstrapped with version 0.9, machine configuration should be regenerated with 0.9 talosctl.
If there are no new messages in
controller-runtime log, it means that controllers finished reconciling successfully.
Checking static pod definitions
Talos generates static pod definitions for
components based on machine configuration.
These definitions can be checked as resources with
talosctl get staticpods:
$ talosctl -n <IP> get staticpods -o yaml get staticpods -o yaml node: 172.20.0.2 metadata: namespace: controlplane type: StaticPods.kubernetes.talos.dev id: kube-apiserver version: 2 phase: running finalizers: - k8s.StaticPodStatus("kube-apiserver") spec: apiVersion: v1 kind: Pod metadata: annotations: talos.dev/config-version: "1" talos.dev/secrets-version: "1" creationTimestamp: null labels: k8s-app: kube-apiserver tier: control-plane name: kube-apiserver namespace: kube-system ...
Status of the static pods can queried with
talosctl get staticpodstatus:
$ talosctl -n <IP> get staticpodstatus NODE NAMESPACE TYPE ID VERSION READY 172.20.0.2 controlplane StaticPodStatus kube-system/kube-apiserver-talos-default-master-1 1 True 172.20.0.2 controlplane StaticPodStatus kube-system/kube-controller-manager-talos-default-master-1 1 True 172.20.0.2 controlplane StaticPodStatus kube-system/kube-scheduler-talos-default-master-1 1 True
Most important status is
Ready printed as last column, complete status can be fetched by adding
-o yaml flag.
Checking bootstrap manifests
As part of bootstrap process, Talos injects bootstrap manifests into Kubernetes API server. There are two kinds of manifests: system manifests built-in into Talos and extra manifests downloaded (custom CNI, extra manifests in the machine config):
$ talosctl -n <IP> get manifests NODE NAMESPACE TYPE ID VERSION 172.20.0.2 controlplane Manifest 00-kubelet-bootstrapping-token 1 172.20.0.2 controlplane Manifest 01-csr-approver-role-binding 1 172.20.0.2 controlplane Manifest 01-csr-node-bootstrap 1 172.20.0.2 controlplane Manifest 01-csr-renewal-role-binding 1 172.20.0.2 controlplane Manifest 02-kube-system-sa-role-binding 1 172.20.0.2 controlplane Manifest 03-default-pod-security-policy 1 172.20.0.2 controlplane Manifest 05-https://docs.projectcalico.org/manifests/calico.yaml 1 172.20.0.2 controlplane Manifest 10-kube-proxy 1 172.20.0.2 controlplane Manifest 11-core-dns 1 172.20.0.2 controlplane Manifest 11-core-dns-svc 1 172.20.0.2 controlplane Manifest 11-kube-config-in-cluster 1
Details of each manifests can be queried by adding
$ talosctl -n <IP> get manifests 01-csr-approver-role-binding --namespace=controlplane -o yaml node: 172.20.0.2 metadata: namespace: controlplane type: Manifests.kubernetes.talos.dev id: 01-csr-approver-role-binding version: 1 phase: running spec: - apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: system-bootstrap-approve-node-client-csr roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:certificates.k8s.io:certificatesigningrequests:nodeclient subjects: - apiGroup: rbac.authorization.k8s.io kind: Group name: system:bootstrappers
Worker node is stuck with
apid health check failures
Control plane nodes have enough secret material to generate
apid server certificates, but worker nodes
depend on control plane
trustd services to generate certificates.
Worker nodes wait for
kubelet to join the cluster, then
apid queries Kubernetes endpoints via control plane
endpoint to find
trustd endpoints, and use
trustd to issue the certficiate.
apid health checks is failing on worker node:
- make sure control plane endpoint is healthy
- check that worker node
kubeletjoined the cluster