A Technical I.T./DevOps Blog
Problem scenario
You are familiar with two different software tools called Yarn. You are not sure what they do or how they are different.
Solution / Yarn Disambiguation
There is a package manager that has some project manager functionalities called yarn. It often works with JavaScript.
This tool has an icon of a one-line drawing of a cat; the original Yarn website had other cat imagery,
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Problem scenario
You want to test your application. You are considering using mock/fake data. But you are concerned that the tests will be insufficient. Is it a best practice to test with production data?
Answer
It depends. We prefer the term “recommended practice” because of questions like these.
Some sources recommend using production data:
…many production issues are due the lack of real(istic) test data…
To ensure software of the highest quality possible,
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Continue reading “Is It a Recommended Practice to Use Production Data when Testing Software?”
Prerequisite
Install make. If you need assistance, see this posting.
Procedures
Run these three commands:
curl https://github.com/gruntwork-io/terragrunt/releases/download/v0.35.18/terragrunt_linux_arm64 –output /tmp/terragrunt_linux_arm64
sudo mv -i /tmp/terragrunt_linux_arm64 /bin/terragrunt
sudo chmod u+x /bin/terragrunt …
Continue reading “How Do You Install and Configure Terragrunt on a Linux Machine?”
Problem scenario
You get a message “kubernetes cluster unreachable” when running a helm, kubectl, az, or eks command. What should you do?
Possible solution #1
Has a router been reconfigured? Has a new firewall rule been imposed? Has a data center gone down that housed the cluster? Did you receive an email about a maintenance window or a configuration change?
Possible solution #2
What are the permissions of the relevant .yaml file?
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Continue reading “How Do You Troubleshoot the Kubernetes Error “cluster unreachable”?”
Question
Which is a higher position, a Senior Engineer or a Staff Engineer?
Answer
Companies do not always conform to a job title convention or standard. However we find that the Staff Engineer title denotes a step above Senior. A Staff Engineer could be below a Principal Engineer however.
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Continue reading “Which Is a Higher Position, a Senior Engineer or a Staff Engineer?”
Problem scenario
You are taking a slice of a Python string. You know that syntax like var_x[-2:] signifies the penultimate character and the last character of a string (called var_x). But you are only seeing one character — not two. You expect to see two (or a different number of characters than what you are seeing). Why is the snippet printing out fewer characters than you expect?
Possible Solution #1
There could be an invisible “\n” attached to the string (e.g.,
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Problem scenario
You want to install gRPC and configure it for Python. How do you do this?
Solution
Prerequisites
You have installed pipe and venv. If you need assistance installing pip, see this posting for Ubuntu/Debian or this posting for a Red Hat derivative (e.g., RHEL, Stream, CentOS, Fedora) or this posting for SUSE.
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Continue reading “How Do You Install gRPC for Python on a Linux Server?”
Problem scenario
When a number of lines of text are read from a file, the Python program sees each line as such. When a number of lines of text are in the program itself, that is you use a multi-line variable assignment in a .py program, Python sees the characters individually and does not distinguish between the different lines. The len() function reflects these differences. You want the Python program to read the text in the program as if it were read from the “with open” and “readlines()” function line-by-line — not character-by-character.
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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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