A Technical I.T./DevOps Blog
Problem scenario
You want to install pip on a RedHat Enterprise Linux server in AWS. What do you do?
Solution
Prerequisites
This assumes that Python has been installed. If it has not, run this command:
sudo yum -y install python3
Procedures
You may want to try these two commands first:
sudo find / -name pip
sudo find / -name pip3
If the above did not help you,
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Continue reading “How Do You Install pip on a RHEL Server in AWS?”
Question
Pages are sizes of a database table read from disk and placed into memory (either virtual memory or into RAM). Is a page always 8 KB in a SQL database?
Answer
No. But they are often 8 KB in size.
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Question
What is a difference between a readinessprobe and a livenessprobe besides how the corresponding fields are used in defining a Pod using YAML?
Answer
At most a failed liveness probe will result in the restarting of a container. At most a failed readiness probe will result in the removing a pod from the endpoint of a service (page 150 of Kubernetes in Action).
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Problem scenario
You are used to AWS Security Groups. You created a firewall rule in GCP. You cannot seem to reach the GCP server. What is wrong?
Possible Solution
Does the GCP firewall rule use the same shorthand notation like this?
x.x.x.x/32
Inbound rules in AWS Security Groups use the /32 to allow an IP address to connect to an EC-2 instance or service.
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Continue reading “How Do You Open a Port to Connect to a GCP server?”
Problem scenario
You want to test connectivity to a database. But you do not know anything about the database beyond its connection information. What SQL statement is universal and guaranteed to work?
Solution
show databases;
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Continue reading “What is a SQL Statement That Will Work for Any MySQL Database?”
Problem scenario
You have a role that you want to execute a Lambda function. What do you do?
Solution
1. Log into the AWS console.
2. Go to IAM -Roles
3. Click on the role you want to change.
4. Click on “Attach policies”
5. In the “Filter policies” field search for “lambda” with no quotes
6.
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Continue reading “How Do You Grant a Role The Ability to Run a Lambda Function?”
Question
What SQL database underlies Elastic Search?
Answer
There is no relational database for Elastic Search.
Elastic Search will have a cluster that is composed of nodes. Nodes are composed of indexes. Indexes are supported by shards. Shards have primary and replica copies. The replica copies vary. The shards are essentially Lucene indexes (according to this site).
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Question
In the context of Linux, what is a system call?
Answer
A system call is a special OS function with a human-readable name (according to page 11 of Sobell’s A Practical Guide to Fedora and RedHat Enterprise Linux). Such a function allows for programs to interact with the kernel (according to page 11 of Sobell’s A Practical Guide to Fedora and RedHat Enterprise Linux).
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Continue reading “In the Context of Linux, what is a System Call?”
Problem scenarios (one or both of the following are happening)
#1 You are getting “botocore.exceptions.NoRegionError: You must specify a region” when you run a Python program (that involves boto and AWS).
#2 You are trying to create a session with a Python/boto program. You are printing out the Session information in your Python program using boto but you see this:
Session(region_name=None)
What should you do?
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Continue reading “How Do You Troubleshoot the boto Message “NoRegionError”?”
Problem scenario
You want to use the rdf4j (Resource Description Framework for Java). You want to install the rdf4j server and workbench. You are using Debian 9 Linux. What should you do?
Solution
Prerequisites
i. We recommend having a 30 GB of hard disk free.
ii. We recommend having 5.75 GB of RAM (it can be a combination of RAM and swap space).
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Continue reading “How Do You Install and Configure the rdf4j Server and Workbench GUI?”