A Technical I.T./DevOps Blog
FDR proclaimed that December 7th would be a day that would live in infamy. Pearl Harbor was attacked in 1941. 80 years later to the day AWS had a major outage (for the us-east-1 region): https://www.theverge.com/2021/12/7/22822332/amazon-server-aws-down-disney-plus-ring-outage
It is an interesting coincidence.
Many people think that the us-east-1 region is the least reliable of Amazon’s regional offerings. Amazon said their “Support Contact Center also relies on the internal AWS network,
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Question
You want definitions of some I.T. terms. In the context of application/system design, what are reliability, scalability and maintainability?
Answer
Reliability: Dependability or suitable for production; the property of performing consistently over time; worthy of being trusted at all times due to fault tolerance. A system that can perform despite hardware failures or regional data center failures is said to have reliability.
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Continue reading “What Are Reliability, Scalability and Maintainability?”
Question
What is cyclomatic complexity or McCabe’s complexity?
Answer
It refers to the number of times a line of source code is entered in its execution.
Number of executionsLevel of complexity1 to 10 Not complex11 to 20Moderately complex21 to 50Really complexMore than 50Too complex
It is advisable to endeavor to keep the cyclomatic complexity as low as possible (according to this external site);
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Question
How do you do a code review?
Answer
Look for consistency in style (adherence to a style guide), functionality, and ensure unit tests and end-to-end tests were performed. Keep an eye out for security issues or maintainability issues. Deploying the code should be straightforward or well documented.
Page 307 of Terraform: Up & Running, 2nd Edition by Yevgeniy Brikman (O’Reilly),
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Problem scenario
You do not think that Apache web server does virtualization (like a hypervisor). But you see the term Virtual Host when you read about Apache web server configurations. What is a VirtualHost in the context of Apache web server?
Solution
“Apache Virtual Hosts A.K.A Virtual Host(Vhost) are used to run more than one web site(domain) using a single IP address.
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Continue reading “What is a VirtualHost in Apache Web Server?”
Problem scenario
You want to list the elastic load balancers in your AWS account. How do you view the ELBs?
Solution
Run this command:
aws elbv2 describe-load-balancers …
Continue reading “What is the AWS CLI Command to List Load Balancers?”
Problem scenario
A Linux user creates a file in a directory and no other manual commands are run. The file is associated with a group that is not the group of the user. What could be the reason?
Answer
The directory had a command like this run:
sudo chgrp group2 /path/to/directory
Then the set GID bit was configured. The chmod 2755 /path/to/directory command would set the GID bit because of the “2” in the numeric notation.
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Question
You have heard of git tags. What are they?
Answer
A Git tag is a pointer to a commit in Git (according to page 129 of Terraform: Up & Running, 2nd Edition by Yevgeniy Brikman (O’Reilly), Copyright 2019, 978-1-492-04690-5).
To create names for these tags, we recommend using semantic versioning as described http://semver.org (because page 129 of Terraform: Up &
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Question
You have heard of Group Variables in Ansible. What are they?
Answer
They are like global variables assigned in a modular way (like Ansible roles). They are ideal when you have Ansible playbooks that run against many different servers. Rather than have a regular variable in a playbook, group variables are taken from a group_vars/ directory. To read more about them, see this posting.
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Continue reading “What is a group_var or Group Variable in Ansible?”
Problem scenario
You are troubleshooting a pipeline in Azure DevOps. You look at the task’s log output. You see a security-threshold flag in a CLI with the value of “low”, “medium”, “high” or “critical” that you think is incorrect or discrepant with another setting. How do you get the flag to be set to the security threshold level of your choice?
Background
The ultimate Snyk command that is run (or commands that are run) is (or are) created from various underlying settings,
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Continue reading “How Do You Configure Snyk’s Threshold Level in Azure DevOps Pipelines?”