A Technical I.T./DevOps Blog
Problem scenario
You are using WordPress and you want to change the icon that your website has (e.g., in a tab of a web browser). How do you change the website’s icon when you use WordPress?
Solution
1. Log into WordPress
2. Appearance -Themes
3. Find which theme is active and click “Customize”.
4. Click “Site Identity”
5.
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Problem scenario
You have heard of bottom-up programming and top-down programming. How are the two types different?
Solution
A bottom-up programming approach involves composing small sub-solutions into a bigger whole solution. There is an integration of components to make a whole with bottom-up programming. This method can be difficult to create the final, coherent product.
A top-down programming approach involves decomposing a big problem into smaller fragments.
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Problem scenario
You are installing Linux. You get “/dev/nvme0n1 is in use Can not proceed with format operation.” How do you handle this?
Solution
Reboot. Start the installation over. Just rebooting may be able to solve it.
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Problem scenario
In Python if you test if a value is in a dictionary, does it look at the keys, the values, or both?
For example, you have code like this:
good_kv = {}
good_kv[”a”] = 1
good_kv[”b”] = 2
good_kv[”c”] = 3
if “b” in good_kv:
print(“The value is in the dictionary!”)
else:
print(“The value is not in the dictionary!”)
print (“testing keys of dictionary above and values of dictionaries below”)
if 3 in good_kv:
print(“The value is in the dictionary!”)
else:
print(“The value is not in the dictionary!”)
Do dictionaries keys,
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Continue reading “Do “if x in dic” Statements Look at Keys or Values in Python Dictionaries?”
Problem scenario
You have a problem with Pods not starting up. They have a status of “CrashLoopBackOff”. What should you do?
Possible Solution #1
Can the Pods start in a lower environment with minimal utilization? Being able to reproduce the problem can help. Trying the YAML in an optimal environment can help you pinpoint the error (e.g., traffic may be high in a production environment).
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Continue reading “How Do You Troubleshoot the Kubernetes Pods Error “CrashLoopBackOff”?”
Problem scenario
You are working with Kubernetes. A PVC cannot be mounted. It seems like the Persistent Volume is still in use. What should you do?
Possible Solution #1
Find out about the volume attachments with these commands:
kubectl get volumeattachment
kubectl get pv
Find the Pods that use it. Is unmounting working? Perhaps the unmounting process has a problem.
Run kubectl describe pod foobar (where “foobar” is the name of the Pod trying to use the PVC).
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Continue reading “How Do You Troubleshoot a PVC That Appears to Still Be in Use?”
Problem scenario
Python can compile source code. There is a process that happens. What form does the code take in the interim (before byte code is created)?
Solution
Abstract Syntax Tree (according to page 175 of Expert Python Programming by Jaworski and Ziade). There is an ast module that allows you to interact with the Abstract Syntax Tree via its grammar.
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Problem scenario
You have a file that is in an executable directory. This file allows a user to execute it.
You run a command, but you get something like this as the output:
/usr/bin/foobar: line 1: syntax error near unexpected token `<‘
/usr/bin/foobar: line 1: `<html<bodyYou are being <a href=”https://objects.githubusercontent.com/github-production-release-asset-abcd/123456789/1234568d-5290-4412-bb2b-abcd?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWABCD1234%2F20220113%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20200113T184113Z&X-Amz-Expires=300&X-Amz-Signature=79cfe429ab0794f4ef1234fd567891cc2ae0a0d2513abcdefgaa97b37e681a856&X-Amz-SignedHeaders=host&actor_id=0&key_id=0&repo_id=59522149&response-content-disposition=attachment%3B%20filename%3Dfoobar_linux_arm64&response-content-type=application%2Foctet-stream”redirected</a.</body</html’
What should you do?
Solution
Check the contents of the binary file you are running.
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Problem scenario
You are curious why an “S” with a line through it is the sign of the dollar. Where did the cash sign “$” (or dollar symbol) originate?
Answer
It is not clear, but it appears to have something to do with Spanish coinage with “pesos” meaning “pieces” and an abbreviation would be “ps”. In smaller coins or on containers, this abbreviation may have been jumbled or pushed the individual letters together closely.
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Continue reading “Where Does the Dollar Sign “$” Come from?”
Problem scenario
You want to design a system without a single point of failure. How can you ensure a load balancer is not a single point of failure?
Solution
Have DNS route to two or more load balancers. DNS does not know the back-end servers’ or pods’ health statuses, according to a StackOverflow.com posting. Therefore you would want to configure the TTL governing the networking of the DNS to be short to ensure DNS services are aware of a web server that is down (according to a Quora posting).
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