A Technical I.T./DevOps Blog
CI is not always automated. “CI acts as a safety net that lets developers prevent many issues before they reach users. As a result, developers ship code with more confidence, but not necessarily faster — the deployment process may still be manual, long, and error-prone.” This quote was taken from this website.
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Problem scenario
You are trying to find the SSH logs in Fedora. Where should you look?
Possible solution #1
/var/log/secure/
Possible solution #2
Check these locations:
/var/log/ssh/
/var/log/auth.log
Possible solution #3
/var/log/messages
(Many other applications write to this file besides SSH.)
Possible solution #4
They could be stored in binary format in /var/log/journal/ …
Run this command: journalctl -u sshd
Look at the output.
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Question
You have heard about different types of containers and seek a disambiguation. Can containers be disambiguated?
Answer
One type of container is a virtual environment like Docker. Another type of container is a data structure of a programming language such as an array, set, list, tuple, or dictionary. These different types of collections of data are called containers.
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Question
You know cgroups provide isolation (along with namespaces in the context of containers). But what exactly are cgroups?
Answer
cgroups enforce hard limits of subsystems to allow efficient allocation of resources of the super-system.
Cgroups allow you to allocate resources — such as CPU time, system memory, network bandwidth, or combinations of these resources — among user-defined groups of tasks (processes) running on a system.
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Problem scenario
A server is hosting a website. On the server, nmap -Pn x.x.x.x is showing port 80 is listening on the server itself. From another server this nmap -Pn x.x.x.x command is showing no ports (or a subset of the ports) are listening. What is the cause of this?
Possible Solution #1
There is a firewall on the webserver that is causing this.
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Continue reading “How Do You Troubleshoot Connectivity over Port 80 when You Know It Is Listening?”
Problem scenario
You have a Pod that you want to run on a worker node. Its status is “Pending.” What can you do to get the Pod to proceed (and what are some common root causes for this problem)?
Background
A common root cause is that the nodes have insufficient resources for the Pod (e.g., insufficient CPU or memory).
Possible Solution #1
Wait.
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Continue reading “Why is a Kubernetes Pod’s Status “Pending”, and What Can Be Done about It?”
Problem scenario
You are debating on using branching with your repositories or using trunk-based development (with virtually no other branches). Is it a best practice to develop on the mainline (with branching infrequently if ever)?
Solution
Maybe. It is not clear.
In Support of the “Yes” / You Should Use Branches
In practice many companies use Git Flow or other branches in their Git repositories.
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Continue reading “Is It a Best/Recommended Practice to Use Branching with Version Control Systems?”
Question
What is software-defined infrastructure?
Answer
There is no universally accepted definition of software-defined infrastructure (according to Techopedia).
We define it as infrastructure that is provisioned and controlled by software. (There is physical infrastructure that powers or underlies SDI.) The provisioning and configuring of virtual machines is one example of SDI. OpenStack and Ericsson’s SDI Manager are other examples of SDI.
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Problem scenario
Androids have home screens (which are the equivalent of a Windows, Mac or Linux desktop). How do you get an application to be easily accessed from the home screen (rather than needing to search for it and drill down each time)?
Solution
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To learn more about Python, see this site https://jobtensor.com/Python-Introduction.
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