A Technical I.T./DevOps Blog
Problem scenario
You want to use the ENTRYPOINT and CMD keywords in a Dockerfile. You know that the value of CMD amounts to a parameter for the ENTRYPOINT value which is executed. You want to verify that the value of ENDPOINT is used in an execution. You want the Dockerfile to be simple to illustrate these reserved words. What do you do?
Solution
Prerequisite
Install Docker.
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Problem scenario
You have configured dbconfig.xml for JIRA 7.x to use Oracle 12. But JIRA is not working correctly when you try to start it. What should you do with your dbconfig.xml file?
Solution
Atlassian’s website, as of 8/30/18, recommends having “oracle10g”, an unsupported version, in the dbconfig.xml file. This is despite the fact that Oracle 10 and Oracle 11 are not supported for JIRA 7.x according to Atlassian’s site here.
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Problem scenario
You think that there is disk contention with the various processes on your Linux server. You think that the I/O activity is too high and potentially creating a bottleneck. What do you do to learn more about disk utilization?
Solution
1. To learn the names of the underlying disks on your Linux system, run this command:
ls -lh /dev/disk/by-path
2.
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Problem scenario
You want to see if an Ansible playbook is injecting (or leaving) two braces, “{{” or “}}”, in a specific file on Linux. These symbols can be injected accidentally with little notification. Variable substitution could fail during the course of a playbook run. This is a subtle problem that may have no alert. You want some debugging to check for these symbols. How do you know a file on a managed node does not have a “{{” or “}}”?
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Continue reading “Using Ansible How Do You Search The Contents of a File on Linux for “{{” or “}}”?”
Problem scenario
You read about what Jenkinsfiles are. Coveros.com defines them as “Jenkinsfiles, using a domain specific language based on the Groovy programming language, are persistent files that model delivery pipelines “as code”, containing the complete set of encoded steps (steps, nodes, and stages) necessary to define the entire application life-cycle.”
How do you use a Jenkinsfile with Declarative pipeline syntax?
Solution
Overview
A Declarative pipeline syntax has four mandatory sections with each of these reserved words: agent,
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Problem scenario
You want to clone a specific branch from Git. But you do not want to clone the master branch. How do you clone the branch named “develop”?
Solution
1. Clone down the repository as normal with a command like this (but replace <SSH or HTTP constructor of repo> with the remote repository):
git clone <SSH or HTTP constructor of repo>
2.
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Continue reading “How Do You Clone Down a Specific Branch of a Repository from Git?”
Problem scenario
You are trying to install a new package or apply yum updates on a CentOS/RHEL/Fedora server. But you get 404 errors or “pycurl error 22” as the result of your yum commands. How do you use yum to install a new package or apply a new update?
Solution
Run this command: sudo yum clean all
Now your yum commands should work.
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Continue reading “How Do You Troubleshoot the Message “pycurl error 22”?”
Question
You know of different Kubernetes components: the Kubernetes Service, the Kubelet, and the Kubernetes API. What do these components do and how are they different?
Answer
A Kubernetes service is an entity, that may span nodes, that keeps a group of Pods functional and coherent (paraphrased from this site). A “[s]ervice will get its own IP address and port” as quoted from page 339 of Kubernetes in Action.
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Problem scenario
Both kubeadm and kubectl are tools and commands for Kubernetes. What are the differences between them?
Answer
kubeadm is for creating new Kubernetes clusters (as paraphrased from this Kubernetes.io page). The command can be used to create both master nodes as well as worker nodes (taken from pg 575 Kubernetes in Action).
kubectl is for running operations on one or more existing Kubernetes clusters (as paraphrased from this
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Continue reading “What Is The Difference between kubeadm and kubectl?”
Problem scenario
You have heard different pronunciations of Nagios. How do you pronounce it?
Solution
Four of the first seven pronunciations found here support the pronunciation of Nagios with a hard “g” not a soft “g” (like a “j” sound).
This external link suggests the hard “g” is correct.
We believe that Ethan Galstad pronounces it with a hard “g.”
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