A Technical I.T./DevOps Blog
Problem scenario
You get an error about a certificate not working with your host/server name. One of the following apply to your situation:
When you use “docker login” you get this message:
“Error response from daemon: x509: certificate is not valid for your server”
OR
When you try to use curl to the Docker registry server you get this error:
curl: (51) SSL: certificate subject name
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People who come to this blog, and homeschooled people, often learn from Google or other search engines. The woman who wrote the song “Mary Had a Little Lamb,” Sarah Josepha Hale, was homeschooled herself. She made two historic contributions, one was musical and the other was political. She influenced Abraham Lincoln to make Thanksgiving a national holiday for many years before it was officially recognized. Wikipedia reports that she was from New England where people regularly celebrated Thanksgiving for years before it was was proclaimed as the third national holiday in 1863.
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Continue reading “The Histories Behind the American Thanksgiving(s)”
Problem scenario
You have a Red Hat Enterprise Linux server in Azure. How do you install Docker on it?
Solution
Run these three commands:
sudo yum -y install docker
sudo groupadd docker
sudo usermod -aG docker ec2-user
FFR
For directions for install Docker to an AWS instance of RHEL, see this link.
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Continue reading “How Do You Install Docker on a RHEL VM in Azure?”
Updated 2/10/22
Answer
DevSecOps is the integration of security practices with DevOps. DevOps may be a culture of automation (as Stackify says), a blend of disciplines (development and operations), or a key word in a job title (e.g., DevOps Engineer or DevOps Architect). DevSecOps seeks to rapidly integrate security measures into development and operations and avoid security specialists working in separate and relatively isolated teams. By having security-minded professionals in the same team,
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Continue reading “What is DevSecOps (or DevOpsSec, SecDevOps, or rugged DevOps)?”
Question
What is a “data swamp”?
Answer
A data swamp is best defined as a severely degraded data lake. The term data swamp connotes poor governance and negligent management that caused a data lake to gradually lose its value. A data swamp is data lake that was once useful but through negligent utilization can no longer be used by even highly talented analytics professionals.
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Question
Erasure coding versus negative coding: what is the difference?
Answer
In the verbose output of a Hadoop or mapred job, you may have seen “INFO mapreduce.JobResourceUploader: Disabling Erasure Coding for path:”
Erasure coding is a fault-tolerant storage mechanism. Like replication the usable capacity of the disks participating in such a mechanism is not fully utilized as in a RAID 0 configuration.
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Continue reading “What Is the Difference between Erasure Coding and Negative Coding?”
Question
What is the difference between negative coding and throw-away prototyping?
Answer
“Plan to throw one away…” -Frederick P. Brooks, Jr. (Taken from page 266 of The Mythical Man-Month).
Both negative coding and throw-away prototyping involve eliminating lines of code. But this is the only similarity they have. Negative coding is contrasted from throw-away prototyping in that the former is a good practice for production systems and long-term use whereas the latter is designed to be temporary.
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Problem scenario
You have a .yaml configuration file that works with the kubectl command to create a deployment. You want to change the source image from the hub.docker.com to a Google container source. How do you configure the .yaml file to obtain the image from a Google container registry instead of Docker Hub?
Your .yaml file has these four lines (among other lines):
spec:
containers:
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Problem scenario
You have a Docker host that is running Linux (the server with Docker containers). You want to run commands inside a Docker container. How do you get into a Docker container?
Solution
Prerequisite
You need to know the container ID of a running container. To find it run this: docker ps -a
Procedures
Run this command:
docker exec -it <container IDbash
You may want to see this
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Problem scenario
You have a Linux server in AWS and another Linux server in Azure. You want to use scp without a password to transfer files rapidly. How do you configure passwordless SSH authentication between the two servers?
Solution
1. Run this command on each server:
ssh-keygen -t rsa -P “”
# Accept the default prompt by pressing enter.
2.i. Run this command on the AWS instance (replace “ubuntu” with “ec2-user” if the AWS instance is a RHEL server):
cat /home/ubuntu/.ssh/id_rsa.pub
2.ii.
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