A Technical I.T./DevOps Blog
Problem scenario
You are using Linux, and you run top, and you see this:
top – 21:38:04 up 14 days, 12:12, 1 user, load average: 5.30, 5.10, 4.90
Tasks: 54 total, 15 running, 39 sleeping, 0 stopped, 0 zombie
%Cpu(s): 11.7 us, 13.7 sy, 0.0 ni, 74.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
How can the load average be so high with so much CPU being idle?
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Continue reading “How Can a Linux Have a Load above 5 with a High Percentage of CPU Being Idle?”
Problem scenario
When you run a kubectl rollout history deployment foobar command, the “CHANGE-CAUSE” is empty for certain rows (revision numbers). What can you do to keep this column with useful descriptions (or relevant commands)?
Possible Solution #1
Going forward, use the –record flag when running kubectl create [deployment] or kubectl set image deployment … commands.
Possible Solution #2
Manually edit the manifest of the resource in the deployment.
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Problem scenario
kubectl commands are failing with an error message like this: “Unable to connect to the server: dial tcp: lookup ABCD123EFG.gr7.us-west-1.eks.amazonaws.com on x.x.x.x:53: no such host”
How do you get kubectl commands to work?
Possible Solution #1
If you are using EKS and you have the name of the cluster (e.g., “foobar”), run a command like this:
aws eks update-kubeconfig –name foobar
Possible Solution #2
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Problem scenario
You run a kubectl command, but you receive one of the following error messages:
Warning FailedScheduling default-scheduler no nodes available to schedule pods
No resources found
What should you do?
Possible Solution #1
Did the control plane lose connectivity with the worker nodes? An intermediate network device such as a firewall may have been implemented. Did a data center become unavailable?
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Problem scenario
In the AWS Management Console, you cannot add a Node to an EKS cluster. The “Node IAM Role” never has any option. You click the “refresh” arrow, but all you see is “No roles found. Follow the link above to create a new role.” What should you do?
Solution
1. Install and configure the AWS CLI. If you need assistance with this,
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Problem scenario
You want to configure the maximum number of Kubernetes readiness probe failures. How do you set this amount?
Solution
Use the failureThreshold setting.
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Continue reading “How Do You Configure the Kubernetes readiness Probe Max Failure Limit?”
Problem scenario
You want to back up many different emails from a web-based email. You cannot select several and print them all at once. What should you do?
Solution
Prerequisite
This assumes your web-based email can be configured to work with a desktop email client (such as Outlook).
Procedures
Install and configure Thunderbird, Outlook or an email client.
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Continue reading “How Do You Back Up Many Emails from a Web-based Email Quickly?”
Problem scenario
Your Kubernetes cluster is not working. The nodes are not ready. You see your Kubernetes nodes are not ready (with kubectl get nodes). You also see this error from a kubectl describe node foobar command:
runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
What should you do?
(If you get a different error, see this posting How Do You Troubleshoot a Kubernetes Cluster That is Not Working at the Node Level?
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Continue reading “How Do You Get Kubernetes Nodes to Be Ready?”
Problem scenario
You want to know what CNI plugin your Kubernetes cluster is using (e.g., Flannel, Calico, Weave Net, Romana or another one). What do you do?
Possible solution
“You can install only one Pod network per cluster.” taken from Kubernetes.io.
Go to a worker node and run these commands and look at the output:
ls -lh /etc/cni/net.d
ls -lh /opt/cni/bin | grep -i flannel
ls -lh /opt/cni/bin | grep -i calico
Use the sudo find / -name command to search for Romana or Weavenet vestiges.
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Problem scenario
You want to do some pre-testing on the .yaml file(s) you will use with kubectl. How do you validate a .yaml file has correct syntax for Kubernetes?
Possible Solution #1
Try this command:
kubectl apply –validate=true –dry-run=true –filename=nameofyourfile.yaml
Possible Solution #2
Try this website:
https://www.kubeyaml.com/
Possible Solution #3
Try kubeval: https://www.kubeval.com/
Possible Solution #4
Use Copper: http://copper.sh/
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Continue reading “How Do You Tell If the .yaml File for a kubectl Command Will Work?”