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Troubleshooting Tools

Help! Something is wrong with my Compliant Kubernetes cluster. Fear no more, this guide will help you make sense.

This guide assumes that:

  • You have pre-requisites installed.
  • Your environment variables, in particular CK8S_CONFIG_PATH is set.
  • Your config folder (e.g. for OpenStack) is available.
  • compliantkubernetes-apps and compliantkubernetes-kubespray is available.

I have no clue where to start

If you get lost, start checking from the "physical layer" and up.

Are the Nodes still accessible via SSH?

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i ${CK8S_CONFIG_PATH}/${CLUSTER}-config/inventory.ini all -m ping
done

Are the Nodes "doing fine"?

Dmesg should not display unexpected messages. OOM will show up here.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i ${CK8S_CONFIG_PATH}/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; dmesg | tail -n 10'
done

Uptime should show high uptime (e.g., days) and low load (e.g., less than 3):

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; uptime'
done

Any process that uses too much CPU?

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; ps -Ao user,uid,comm,pid,pcpu,tty --sort=-pcpu | head -n 6'
done

Is there enough disk space? All writeable file-systems should have at least 30% free.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; df -h'
done

Is there enough available memory? There should be at least a few GB of available memory.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; cat /proc/meminfo | grep Available'
done

Can Nodes access the Internet?

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; hostname; curl --silent  https://checkip.amazonaws.com'
done

Are the Nodes having the proper time? You should see System clock synchronized: yes and NTP service: active.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'echo; timedatectl status'
done

Is the base OS doing fine?

We generally run the latest Ubuntu LTS, at the time of this writing Ubuntu 20.04 LTS.

You can confirm this by doing:

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'cat /etc/lsb-release'
done

Are systemd units running fine? You should see running and not degraded.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible -i $CK8S_CONFIG_PATH/${CLUSTER}-config/inventory.ini all -m shell -a 'systemctl is-system-running'
done

Are the Kubernetes clusters doing fine?

Are the Nodes reporting in on Kubernetes? All Kubernetes Nodes, both control-plane and workers, should be Ready:

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} get nodes'
done

Is Rook doing fine?

If Rook is installed, is Rook doing fine? You should see HEALTH_OK.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} -n rook-ceph apply -f ./compliantkubernetes-kubespray/rook/toolbox-deploy.yaml'
done

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} -n rook-ceph exec deploy/rook-ceph-tools -- ceph status'
done

Are Kubernetes Pods doing fine?

Pods should be Running or Completed, and fully Ready (e.g., 1/1 or 6/6)?

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} get --all-namespaces pods'
done

Are all Deployments fine? Deployments should show all Pods Ready, Up-to-date and Available (e.g., 2/2 2 2).

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} get --all-namespaces deployments'
done

Are all DaemonSets fine? DaemonSets should show as many Pods Desired, Current, Ready and Up-to-date, as Desired.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    sops exec-file ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml \
        'kubectl --kubeconfig {} get --all-namespaces ds'
done

Are Helm Releases fine?

All Releases should be deployed.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    export KUBECONFIG=kube_config_$CLUSTER.yaml
    sops -d ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml > $KUBECONFIG
    helm list --all --all-namespaces
    shred $KUBECONFIG
done

Is cert-manager doing fine?

Are (Cluster)Issuers fine? All Resources should be READY=True or valid.

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    export KUBECONFIG=kube_config_$CLUSTER.yaml
    sops -d ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml > $KUBECONFIG
    kubectl get clusterissuers,issuers,certificates,orders,challenges --all-namespaces
    shred $KUBECONFIG
done

Where do I find the Nodes public and private IP?

find . -name inventory.ini

or

for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    ansible-inventory -i ${CK8S_CONFIG_PATH}/${CLUSTER}-config/inventory.ini --list all
done

ansible_host is usually the public IP, while ip is usually the private IP.

Node cannot be access via SSH

Important

Make sure it is "not you". Are you well connected to the VPN? Is this the only Node which lost SSH access?

Important

If you are using Rook, it is usually set up with replication 2, which means it can tolerate one restarting Node. Make sure that, either Rook is healthy or that you are really sure you are restarting the right Node.

Try connecting to the unhealthy Node via a different Node and internal IP:

UNHEALTHY_NODE=172.0.10.205  # You lost access to this one
JUMP_NODE=89.145.xxx.yyy  # You have access to this one

ssh -J ubuntu@$JUMP_NODE ubuntu@$UNHEALTHY_NODE

Try rebooting the Node via cloud provider specific CLI:

UNHEALTHY_NODE=cksc-worker-2

# Example for ExoScale
exo vm reboot --force $UNHEALTHY_NODE

If using Rook make sure its health goes back to HEALTH_OK.

A Node has incorrect time

Incorrect time on a Node can have sever consequences with replication and monitoring. In fact, if you follow ISO 27001, A.12.4.4 Clock Synchronisation requires you to ensure clocks are synchronized.

These days, Linux distributions should come out-of-the-box with timesyncd for time synchronization via NTP.

To figure out what is wrong, SSH into the target Node and try the following:

sudo systemctl status systemd-timesyncd
sudo journalctl --unit systemd-timesyncd
sudo timedatectl status
sudo timedatectl timesync-status
sudo timedatectl show-timesync

Possible causes include incorrect NTP server settings, or NTP being blocked by firewall. For reminder, NTP works over UDP port 123.

Node seems not fine

Important

If you are using Rook, it is usually set up with replication 2, which means it can tolerate one restarting Node. Make sure that, either Rook is healthy or that you are really sure you are restarting the right Node.

Try rebooting the Node:

UNHEALTHY_NODE=89.145.xxx.yyy

ssh ubuntu@$UNHEALTHY_NODE sudo reboot

If using Rook make sure its health goes back to HEALTH_OK.

Node seems really not fine. I want a new one.

Is it 2AM? Do not replace Nodes, instead simply add a new one. You might run out of capacity, you might lose redundancy, you might replace the wrong Node. Prefer to add a Node and see if that solves the problem.

Okay, I want to add a new Node.

Prefer this option if you "quickly" need to add CPU, memory or storage (i.e., Rook) capacity.

First, check for infrastructure drift, as shown here.

Depending on your provider:

  1. Add a new Node by editing the *.tfvars.
  2. Re-apply Terraform.
  3. Re-create the inventory.ini (skip this step if the cluster is using a dynamic inventory).
  4. Re-apply Kubespray.
  5. Re-fix the Kubernetes API URL.

Check that the new Node joined the cluster, as shown here.

A systemd unit failed

SSH into the Node. Check which systemd unit is failing:

systemctl --failed

Gather more information:

FAILED_UNIT=fwupd-refresh.service

systemctl status $FAILED_UNIT
journalctl --unit $FAILED_UNIT

Rook seems not fine

Please check the following upstream documents:

Pod seems not fine

Before starting, set up a handy environment:

CLUSTER=cksc  # Cluster containing the unhealthy Pod

export KUBECONFIG=kube_config_$CLUSTER.yaml
sops -d ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml > $KUBECONFIG

Check that you are on the right cluster:

kubectl get nodes

Find the name of the Pod which is not fine:

kubectl get pod -A

# Copy-paste the Pod and Pod namespace below
UNHEALTHY_POD=prometheus-kube-prometheus-stack-prometheus-0
UNHEALTHY_POD_NAMESPACE=monitoring

Gather some "evidence" for later diagnostics, when the heat is over:

kubectl describe pod -n $UNHEALTHY_POD_NAMESPACE $UNHEALTHY_POD
kubectl logs -n $UNHEALTHY_POD_NAMESPACE $UNHEALTHY_POD

Try to kill and check if the underlying Deployment, StatefulSet or DaemonSet will restart it:

kubectl delete pod -n $UNHEALTHY_POD_NAMESPACE $UNHEALTHY_POD
kubectl get pod -A --watch

Helm Release is failed

Before starting, set up a handy environment:

CLUSTER=cksc  # Cluster containing the failed Release

export KUBECONFIG=kube_config_$CLUSTER.yaml
sops -d ${CK8S_CONFIG_PATH}/.state/kube_config_$CLUSTER.yaml > $KUBECONFIG

Check that you are on the right cluster:

kubectl get nodes

Find the failed Release:

helm ls --all-namespaces --all

FAILED_RELEASE=user-rbac
FAILED_RELEASE_NAMESPACE=kube-system

Just to make sure, do a drift check, as shown here.

Remove the failed Release:

helm uninstall -n $FAILED_RELEASE_NAMESPACE $FAILED_RELEASE

Re-apply apps according to documentation.

cert-manager is not fine

Follow cert-manager's troubleshooting, specifically:

How do I check if infrastructure drifted due to manual intervention?

Go to the docs of the cloud provider and run Terraform plan instead of apply. For Exoscale, it looks as follows:

TF_SCRIPTS_DIR=$(readlink -f compliantkubernetes-kubespray/kubespray/contrib/terraform/exoscale)
for CLUSTER in ${SERVICE_CLUSTER} "${WORKLOAD_CLUSTERS[@]}"; do
    pushd ${TF_SCRIPTS_DIR}
    export TF_VAR_inventory_file=${CK8S_CONFIG_PATH}/${CLUSTER}-config/inventory.ini
    terraform init
    terraform plan \
        -var-file=${CK8S_CONFIG_PATH}/${CLUSTER}-config/cluster.tfvars \
        -state=${CK8S_CONFIG_PATH}/${CLUSTER}-config/terraform.tfstate
    popd
done

How do I check if the Kubespray setup drifted due to manual intervention?

At the time of this writing, this cannot be done, but efforts are underway.

How do I check if apps drifted due to manual intervention?

# For service cluster
ln -sf $CK8S_CONFIG_PATH/.state/kube_config_${SERVICE_CLUSTER}.yaml $CK8S_CONFIG_PATH/.state/kube_config_sc.yaml
./compliantkubernetes-apps/bin/ck8s ops helmfile sc diff  # Respond "n" if you get WARN
# For the workload clusters
for CLUSTER in "${WORKLOAD_CLUSTERS[@]}"; do
    ln -sf $CK8S_CONFIG_PATH/.state/kube_config_${CLUSTER}.yaml $CK8S_CONFIG_PATH/.state/kube_config_wc.yaml
    ./compliantkubernetes-apps/bin/ck8s ops helmfile wc diff  # Respond "n" if you get WARN
done