Monitoring APIRequestCount in OpenShift

2 min read

Openshift provides an object that tracks the number of requests made to the Kubernetes API server. It provides insights into the load on the cluster, the performance of applications, and helps in capacity planning. By monitoring APIRequestCount, you can identify potential bottlenecks, detect unusual spikes in traffic, and optimize resource allocation.

$ kubectl get apirequestcounts
NAME                                                                           REMOVEDINRELEASE   REQUESTSINCURRENTHOUR   REQUESTSINLAST24H
alertmanagerconfigs.v1alpha1.monitoring.coreos.com                                                6                       1706
alertmanagers.v1.monitoring.coreos.com                                                            20                      2891
apiservices.v1.apiregistration.k8s.io                                                             994                     99521
(...)

11/07/2023

OpenShift 3.11 - custom default route certificate failing with certificate has expired or is not yet valid

2 min read

After trying to set a custom default certificate for the OpenShift routes we might see how it's Pods starts crashing:

$ kubectl get pods
NAME                          READY   STATUS             RESTARTS   AGE
router-10-rh8vf               1/1     Running            0          32m
router-10-f2dt2               0/1     CrashLoopBackOff   6          7m
router-10-m45b7               1/1     Running            0          31m

Checking it's logs we'll get a quite misleading message:

$ kubectl logs router-10-f2dt2 -n default
Error from server: Get https://some.openshift.cluster:10250/containerLogs/default/router-10-f2dt2/router: x509: certificate has expired or is not yet valid

04/07/2023

Running tcpdump on an OpenShift cluster

3 min read

If we want to take a look at the network traffic that we get out of an OpenShift node we can use the oc debug command to spin up a privileged pod with tcpdump installed. This way we don't need to ssh into the worker node.

22/05/2023

Container with alpine failing to execute a file with not found

3 min read

While building a container using alpine as a base image we can get a not found error while trying to execute a file that doesn't make much sense:

$ docker run -it test /usr/local/bin/example-app
exec /usr/local/bin/example-app: no such file or directory

14/11/2022

Using ephemeral containers

3 min read

Starting Kubernetes 1.23, ephemeral containers are enabled by default (in beta though). Using ephemeral containers we can now troubleshoot pods by deploying a temporary container into it with extra privileges or binaries to use

22/08/2022