A Technical I.T./DevOps Blog
Problem scenario
You have been collecting system activity reports with the sar utility. You want to display this data in .csv, .svg, or XML format. How do you install sadf on an Ubuntu/Debian system?
Solution
Run this:
sudo apt -y install sysstat …
Continue reading “How Do You Install sadf on an Ubuntu/Debian Linux System?”
Question
You have a program with four variables that are used in arithmetic, but no other operations happen. (There are no while or for loops at all.) What is the time complexity of such an algorithm?
Answer
O(1). An algorithm, as long as the number of operations is fixed or constant, can be considered to have O(1) time complexity. The source is page 39 of Elements of Programming Interviews in Python.
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Problem scenario
You have load balancers, web servers, and other HTTP technologies that rely on SSL or TLS certificates. Some certificates will be revoked for security reasons. How do you provision new certificates to update them (because they will expire or you want to harden your environment by refreshing the certs as aged certs are more likely to be compromised than young ones)?
Solution
You may want to plan for having lower capacity than normal and therefore schedule the time to do this in production during an off-peak time.
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Problem scenario
You have applied for a job. You are curious what it can pay. Would the interviewer be upset if you asked what the expected pay range is for the position?
Solution
In some jurisdictions private employers must disclose the pay range. If you live in one of those places and you are asking for a remote position, it may be legally required for the employer to disclose it.
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Continue reading “Should You Ask What the Salary Pay Range Is?”
Problem scenario
You are reading about Apache Web Server containers. These are not related to Docker containers. You often see them near or tags. What are Apache Web Server containers?
Answer
They are portions of text that contain Apache web server configuration. (The source of this is https://httpd.apache.org/docs/2.4/sections.html.) The configuration includes directives often related to the VirtualHost in Apache web server.
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Question
What is long-tail latency or tail latency?
Answer
Tail latency is the worst performing time-measured response from an application. Outliers can be described as requests that take far longer than others in a statistical sample. Such irregular durations, with long latencies, are said to be at the tail-end of a chart or graph. Long-tail latency would generally refer to the worst 1% or worst 2% of the requests.
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Problem scenario
You do not have the YAML (.yml or .yaml) files for your Helm deployments.
How do you find the pod manifests for the yaml files when you do not have access to the Helm repos?
Solution
Run this:
helm ls -a -A
The output will show a “Name” on the left most column and a namespace in an inner column.
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Problem scenario
You look at some previous pipelines’ test results. The tests show failing tests. There is a temporal field for “Failing since” and another field called “Failing release.” You have not run the release that is listed as failing in a while. Why isn’t it showing the most recent release?
Possible Solution
The root cause is consecutive failures and possibly a poorly named column heading.
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Problem scenario
You want to use the strace command. How do you use it?
Solution
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Problem scenario
You do not want to use pip or pip3 to install opencv. How do you install opencv (with the -DWITH_FFMPEG=ON flag)?
Solution
Prerequisite
This assumes that cmake has been installed. If you are running Ubuntu/Debian, run this: sudo apt -y install cmake
If you are running CentOS/RHEL/Fedora (some RedHat derivative), run this: sudo yum -y install cmake
If you are running SUSE,
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Continue reading “How Do You Install opencv / cv2 without pip3 so The -DWITH_FFMPEG=ON is Set On?”