Initial troubleshooting

Percona Operator for MySQL uses Custom Resources to manage options for the various components of the cluster.

• PerconaXtraDBCluster Custom Resource with Percona XtraDB Cluster options (it has handy pxc shortname also),

• PerconaXtraDBClusterBackup and PerconaXtraDBClusterRestore Custom Resources contain options for Percona XtraBackup used to backup Percona XtraDB Cluster and to restore it from backups (pxc-backup and pxc-restore shortnames are available for them).

The first thing you can check for the Custom Resource is to query it with kubectl get command:

$ kubectl get pxc

Expected output

NAME       ENDPOINT                   STATUS   PXC   PROXYSQL   HAPROXY   AGE
cluster1   cluster1-haproxy.default   ready    3                3         33d

The Custom Resource should have Ready status.

Note

You can check which Percona’s Custom Resources are present and get some information about them as follows:

$ kubectl api-resources | grep -i percona

Expected output

perconaxtradbclusterbackups       pxc-backup,pxc-backups     pxc.percona.com/v1                     true         PerconaXtraDBClusterBackup
perconaxtradbclusterrestores      pxc-restore,pxc-restores   pxc.percona.com/v1                     true         PerconaXtraDBClusterRestore
perconaxtradbclusters             pxc,pxcs                   pxc.percona.com/v1                     true         PerconaXtraDBCluster

Check the Pods

If Custom Resource is not getting Ready status, it makes sense to check individual Pods. You can do it as follows:

$ kubectl get pods

Expected output

NAME                                               READY   STATUS    RESTARTS   AGE
cluster1-haproxy-0                                 2/2     Running   0          6m17s
cluster1-haproxy-1                                 2/2     Running   0          4m59s
cluster1-haproxy-2                                 2/2     Running   0          4m36s
cluster1-pxc-0                                     3/3     Running   0          6m17s
cluster1-pxc-1                                     3/3     Running   0          5m3s
cluster1-pxc-2                                     3/3     Running   0          3m56s
percona-xtradb-cluster-operator-79966668bd-rswbk   1/1     Running   0          9m54s

The above command provides the following insights:

• READY indicates how many containers in the Pod are ready to serve the traffic. In the above example, cluster1-haproxy-0 Pod has all two containers ready (2/2). For an application to work properly, all containers of the Pod should be ready.
• STATUS indicates the current status of the Pod. The Pod should be in a Running state to confirm that the application is working as expected. You can find out other possible states in the official Kubernetes documentation .
• RESTARTS indicates how many times containers of Pod were restarted. This is impacted by the Container Restart Policy . In an ideal world, the restart count would be zero, meaning no issues from the beginning. If the restart count exceeds zero, it may be reasonable to check why it happens.
• AGE: Indicates how long the Pod is running. Any abnormality in this value needs to be checked.

You can find more details about a specific Pod using the kubectl describe pods <pod-name> command.

$ kubectl describe pods cluster1-pxc-0

Expected output

...
Name:         cluster1-pxc-0
Namespace:    default
...
Controlled By:  StatefulSet/cluster1-pxc
Init Containers:
 pxc-init:
...
Containers:
 pmm-client:
...
 pxc:
...
   Restart Count:  0
   Limits:
     cpu:     1
     memory:  2G
   Requests:
     cpu:      1
     memory:   2G
   Liveness:   exec [/var/lib/mysql/liveness-check.sh] delay=300s timeout=5s period=10s #success=1 #failure=3
   Readiness:  exec [/var/lib/mysql/readiness-check.sh] delay=15s timeout=15s period=30s #success=1 #failure=5
   Environment Variables from:
     pxc-env-vars-pxc  Secret  Optional: true
   Environment:
...
   Mounts:
...
Volumes:
...
Events:                      <none>

This gives a lot of information about containers, resources, container status and also events. So, describe output should be checked to see any abnormalities.

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Last update: 2024-10-29