Troubleshooting Guide

This section highlights some of the common problems users face during and after a MetalK8s installation. If you do not find a solution to a problem you are facing, please reach out to Scality support or create a Github issue.

Bootstrap Installation Errors

Bootstrap Installation fails with no straightforward reason

If during a MetalK8s installation you encounter a failure and the console output does not provide sufficient information in order to pin-point the cause of failure, then re-run the installation with the verbose flag (--verbose).

root@bootstrap $ /srv/scality/metalk8s-2.6.0-dev/bootstrap.sh --verbose

Errors after restarting the Bootstrap node

If you reboot the Bootstrap node and for some reason, some containers (especially the salt-master container) refuses to start then perform the following checks:

  • Check and ensure that the MetalK8s ISO is mounted properly.

    [root@bootstrap vagrant]# mount | grep /srv/scality/metalk8s-2.6.0-dev
    /home/centos/metalk8s.iso on /srv/scality/metalk8s-2.6.0-dev type iso9660 (ro,relatime)
  • If the ISO is unmounted, run the following command which will check the the status of the ISO file and remount it automatically.

    [root@bootstrap vagrant]# salt-call state.sls metalk8s.archives.mounted saltenv=metalk8s-2.6.0-dev
     Summary for local
     ------------
     Succeeded: 3
     Failed:    0

Bootstrap fails and console log is unscrollable

If during a MetalK8s installation, the Bootstrap process fails and the console output is unscrollable then you can consult the Bootstrap logs in /var/log/metalk8s-bootstrap.log.

Account Administration Errors

Forgot the MetalK8s GUI password

If you forget the MetalK8s GUI username and/or password combination, follow this procedure to reset or change it.

General Kubernetes Resource Errors

Pod status shows “CrashLoopBackOff”

If after a MetalK8s installation, you notice some Pods are in a state of “CrashLoopBackOff”, then it means pods are crashing because they start up then immediately exit, thus Kubernetes restarts them and the cycle continues. To get possible clues about this error, run the following commands and inspect the output.

[root@bootstrap vagrant]# kubectl -n kube-system describe pods <pod name>
 Name:                 <pod name>
 Namespace:            kube-system
 Priority:             2000000000
 Priority Class Name:  system-cluster-critical

Persistent Volume Claim(PVC) stuck in “Pending” state

If after provisioning a Volume for a Pod (e.g. Prometheus) and the PVC still hangs in a Pending state, then try checking the following:

  • Check that the volumes have been provisioned and are in a Ready state:

    kubectl describe volume <volume-name>
    [root@bootstrap vagrant]# kubectl describe volume test-volume
     Name:         <volume-name>
     Status:
       Conditions:
         Last Transition Time:  2020-01-14T12:57:56Z
         Last Update Time:      2020-01-14T12:57:56Z
         Status:                True
         Type:                  Ready
    
  • Check that a corresponding PersistentVolume exist:

    [root@bootstrap vagrant]# kubectl get pv
    NAME                     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS  STORAGECLASS             AGE       CLAIM
    <volume-name>              10Gi       RWO            Retain          Bound  <storage-class-name>     4d22h     <persistentvolume-claim-name>
    
  • Check that the PersistentVolume matches the PersistentVolume Claim constraints (size, labels, storage class) by doing the following:

    • Find the name of your PersistentVolume Claim:

      [root@bootstrap vagrant]# kubectl get pvc -n <namespace>
      NAME                             STATUS   VOLUME                 CAPACITY   ACCESS MODES   STORAGECLASS          AGE
      <persistent-volume-claim-name>   Bound    <volume-name>          10Gi       RWO            <storage-class-name>  24h
      
    • Then check the PersistentVolume Claim constraints if they match:

      [root@bootstrap vagrant]# kubectl describe pvc <persistevolume-claim-name> -n <namespace>
      Name:          <persistentvolume-claim-name>
      Namespace:     <namespace>
      StorageClass:  <storage-class-name>
      Status:        Bound
      Volume:        <volume-name>
      Capacity:      10Gi
      Access Modes:  RWO
      VolumeMode:    Filesystem
      
  • If no PersistentVolume exist, then check that the storage operator is up and running.

    [root@bootstrap vagrant]# kubectl -n kube-system get deployments storage-operator
    NAME               READY   UP-TO-DATE   AVAILABLE   AGE
    storage-operator   1/1     1            1           4d22h
    

Access to MetalK8s GUI fails with “undefined backend”

If in the cause of using the MetalK8s GUI, you encounter an “undefined backend” error then perform the following checks:

  • Check that the Ingress pods are running:

    [root@bootstrap vagrant]#  kubectl -n metalk8s-ingress get daemonsets
    NAME                                     DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR                     AGE
    nginx-ingress-control-plane-controller   1         1         1       1            1           node-role.kubernetes.io/master=   4d22h
    nginx-ingress-controller                 1         1         1       1            1           <none>                            4d22h
    
  • Check the Ingress controller logs:

    [root@bootstrap vagrant]# kubectl logs -n metalk8s-ingress nginx-ingress-control-plane-controller-ftg6v
     -------------------------------------------------------------------------------
     NGINX Ingress controller
       Release:       0.26.1
       Build:         git-2de5a893a
       Repository:    https://github.com/kubernetes/ingress-nginx
       nginx version: openresty/1.15.8.2
    

Pod and Service CIDR conflicts

If after installation of a MetalK8s cluster you notice that Pod-to-Pod communication has routing problems, perform the following:

  • Check the configured values for the internal Pod and Service networks:

    [root@bootstrap vagrant]# salt-call pillar.get networks
    local:
        ----------
        control_plane:
            172.21.254.0/28
        pod:
            10.233.0.0/16
        service:
            10.96.0.0/12
        workload_plane:
            172.21.254.32/27
    

    Make sure the configured IP ranges (CIDR notation) do not conflict with your infrastructure.

Todo

  • Add Salt master/minion logs, and explain how to run a specific state from the Salt master.

  • Add troubleshooting for networking issues.