A Technical I.T./DevOps Blog
Problem scenario
You use a variable in an Ansible playbook. The value of the variable is surrounded by quotes and brackets. You may refer to it as punctuation [“”]. You want to assign the variable without the new symbols such as ‘[“”]’. How do you get just the value and no punctuation?
Solution
Do not use quotes or square brackets “[]” around the variable.
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Problem scenario
You have configured Nginx to be an HTTP load balancer (a web server configured to behave as a landing portal that enables traffic to pass through). As a reverse proxy with built-in keywords you have use the “least_conn” directive, but it does not seem to be working. You want inbound network connection requests from your users via web browsers to be relayed to the web servers with the fewest (or least) amount of active connections.
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Continue reading “How Do You Use the least_conn Directive in an Nginx Configuration File?”
One or both of the following scenarios applies.
Problem scenario #1
Try to install kubectl, but you get an error message about it being installed.
Problem scenario #2
You run “man kubectl” but you see no man page. You still think kubectl is installed.
What should you do?
Solution
Run this command: kubectl version
The results should give you some clues as to what is wrong.
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Continue reading “How Do You Know if kubectl Is Installed on Your Linux Server?”
Question
What is SELinux?
Answer
Security-Enhanced Linux (or SELinux) is a kernel module that can be installed and turned on in a Linux server. It categorizes files, hardware resources and processes; to learn more see this posting. It has the ability to restrict access to these categories. If a server is designated as an application server, a database server, or a web server,
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Problem Scenario
You run a “kinit” command. But you receive this:
‘kinit: Cannot find KDC for realm “CONTINUALINTEGRATION.COM” while getting initial credentials’
What should you do?
Solution
Look at the /etc/krb5.conf file. Look at the REALM section. Does it look like this?
[realms]
EXAMPLE.COM =
You need to change “EXAMPLE.COM” to your domain name.
Look also at the libdefaults section.
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Problem scenario
On a Linux server you get “No usable default provider could be found for your system.” What should you do?
Solution
Install VirtualBox. On an Ubuntu server with 0.5 GB of RAM, you can simply run this command:
sudo apt-get -y install virtualbox
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Question
In the context of I.T. (computers, SaaS, and websites) what does the initialism SPA stand for?
Answer
Single-Page Application. To learn more, see this article.
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Problem scenario
You try to copy a file. It fails with “Permission denied.” What should you do?
Possible Solutions
1. Are the permissions of the destination folder/directory permissive? Is you user supposed to be able to write to the destination folder/directory?
2. Is there an open file in the destination directory? Sometimes this can cause unexpected problems (e.g., with Git Bash).
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At the time of writing, we suggest these troubleshooting steps for many I.T. tasks. Some of these will not apply to every problem. But if you do not know where to begin, this can help you with “DevOps block.”
1. Find the word “error” in the logs. Look at a log with vi (e.g., copy the log to a location where it will not be continually written to). Open the copy with vi.
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Continue reading “Excellent Generic Troubleshooting Tips for I.T. work (e.g., DevOps tasks)”
Question
What is a container breakout?
Answer
A container breakout is an the act of a user or process in a container gaining access to its underlying host server. Containerization is the isolation of processes and/or disk space on a server. A container is isolated from the host server via cgroups and namespaces. Bypassing the cgroup(s) and namespace(s) through intentional acts can be desirable for legitimate systems engineers.
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