A Technical I.T./DevOps Blog
Question
You have been asked to explain how an external request for a website is routed and ultimately fulfilled by a pod in Kubernetes via an ingress controller. When a web browser downloads a website via HTTP and the website is running from a Kubernetes cluster, how does an individual container provide the HTML and/or data? How is external traffic routed to an underlying pod in a Kubernetes Cluster?
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Problem scenario
You want the dot utility to transform “terraform graph” command output to usable files. What should you do?
Solution
Run this command: sudo yum -y install graphviz
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Continue reading “How Do You Install the dot Utility on a CentOS/RHEL/Fedora Server?”
Question
You have read about the DOM. What is the Document Object Model and what do the three words mean in this phrase?
Answer
“The Document Object Model (DOM) is an abstract representation of an HTML document that can be queried and manipulated through its API.” This quote was taken from page 62 of The Web Application Hacker’s Handbook 2nd Edition.
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Problem scenario
You are using Oracle VirtualBox. You get “ssh connect to host x.x.x.x port 22: No route to host”. What do you do?
Solution
In Oracle VirtualBox, go to Devices -Network -Network Settings. Is it attached to “Internal Network”? Try attaching it to “Bridged Adapter” instead.
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Problem scenario
Your Python program is trying to invoke a Bash command. But you get an error like this: “FileNotFoundError: [Errno 2] No such file or directory”. What should you do?
Possible Solution #1 Use the shell=True command if your environment is secure. This is not a recommended practice from a security perspective. We have found that this with shell=True syntax can make the error go away:
subprocess.Popen(variableofcommand,
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Problem scenario
You only want your Android phone to ring if certain phone numbers call you. You have “blocked unknown callers” on your Android phone with certain settings. You went to the Phone app -three vertical dots -Settings -Block numbers -Block unknown callers
But you still get calls, or your phone still rings, when unknown callers call you.
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Question
You have seen the initialism RDS. What does this term mean?
Answer
Normally it is a reference to AWS’ PaaS offering for relational databases called Amazon Relational Database Service.
The term RDS can refer to Reference Data Services in the Microsoft realm (e.g., Azure or SQL Server). Here is more information.
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Continue reading “What Does RDS Mean in the Context of Databases?”
Problem scenario
You are using the AWS CLI. You want to know what region is being used by default. You do not what to use the aws configure command. What should you do?
Solution
Run this:
cat ~/.aws/config …
Continue reading “How Do You Determine the AWS CLI Default Region?”
Problem scenario
You have some JSON files like this:
$cat first.json
{“bird”: {“name”: “singy”, “species”: “sparrow”, “amount”: “45”}}
$ cat second.json
{“bird”: {“name”: “flighty”, “species”: “seagull”, “amount”: “21”}}
Within the “bird” key there are other keys. How do you create a tuple with the species values?
Solution
Place first.json, second.json and the Python program below (called reader.py) in the same directory.
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Problem scenario
You want an FTP client on your RHEL server despite it being insecure. What should you do?
Solution
We do not recommend using FTP for security reasons. However it is still used in today’s world. To install an ftp client, run this:
sudo yum -y install ftp …
Continue reading “How Do You Solve the Error “ftp command not found” or Install an FTP Client?”