What Are The Kubernetes Concepts “pod label,” “label selector,” and “pod selector”?

Question
What is the difference between these three two-word terms “pod label,” “label selector,” and “pod selector”?

Answer
This answer provides details on what these are and provides some information on how they are different.

pod label: It is an inherent attribute of the pod. It can be changed via a command like this: kubectl label pod new-podlabel version=5.5 These statements were based on Assistanz.com.

How Do You Get the mysql Command to Work from an Ubuntu Linux Command Line?

Problem scenario
The mysql command does not work from Ubuntu. You try to run a “mysql” command but you get “command not found.” What do you do to install a mysql CLI utility?

Solution
Run one of the following:

sudo apt -y install mysql-client-core-5.7
sudo apt -y install mariadb-client-core-10.1

These commands may help you too:

apt-cache search mysql-client
apt-cache search mariadb-client
sudo apt -y install mycli
sudo mysql -u root

What Do You Do when Cassandra Stalls on “Initializing IndexInfo”?

Problem scenario
When you start Cassandra you see a message such as this:

INFO [main] 2018-02-03 08:45:55,257 ColumnFamilyStore.java:389 – Initializing system.IndexInfo

What should you do?

Possible Solution #1
Try rebooting the server. This could help the problem.

Possible Solution #2
This next one is merely a workaround. It is not a best practice.

How Do You Use Terraform to Create a Server in GCP?

Problem scenario
You want to use infrastructure as a code with Terraform and GCP. How do you use a .tf file to create a virtual machine in Google Cloud Platform?

Solution
Prerequisite

This assumes you have installed Terraform. If you need assistance with this, see this posting.

Procedures

1. Obtain the account.json file for your GCP account.

How Do You Troubleshoot Error Messages in a Bash Script?

Problem scenario
You run a shell or bash script but you receive an error message such as one of the following:

$’\r’: command not found
line:55 syntax error: unexpected end of file

Solution
Did you download the file from the internet directly to the Unix system? The root cause could be that there are invisible characters in the file.

If you can copy the content of the text into the Linux machine and have it run as a script,

How Do You Delete VM Instances from GCP That Pertain to GKE?

Problem Scenario
You have some GKE standard clusters that you want deleted. You try to delete them, but they do not go away. What should you do?

Solution
Root cause: Kubernetes clusters are self-healing. They are acting as they were designed. Once the instance group is deleted, you will be able to delete the instances via the web UI or via Google’s Cloud Shell.

Why Would a MongoDB Container Work on an Ubuntu Host but Not a SUSE Host?

Problem scenario
You have two Linux servers in AWS, and each one has the same flavor (i.e., same amount of RAM and same number of processors). One is Ubuntu and another is SUSE. These commands will create working containers in Ubuntu:

docker run –name name1-mongo -d mongo
docker run –name name2-mongo -d mongo:2

This command will not create a working container in SUSE:

docker run –name name2-mongo -d mongo:2

The container that is created will never start.

How Do You Get Azure PowerShell Commands Involving Storage to Work when They Are Returning an Error “not recognized”?

Problem scenario
Many Azure commands are failing. You installed the Azure module. But commands related to “Azure Storage” all return “not recognized as the name of a cmdlet, function, script file or operable program.”

You see messages like this:

New-AzureStorageAccount : A parameter cannot be found that matches parameter name ‘ResourceGroupName’.
At line:4 char:25
+ New-AzureStorageAccount -ResourceGroupName “contIntGroup” -AccountNam …
+ ~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (:) [New-AzureStorageAccount], …

How Do You Create a Jenkins CI/CD Pipeline That Starts when Code is Checked into Atlassian Bitbucket?

Problem scenario
To trigger a Jenkins build after code is inserted into a Bitbucket repository, I have two options. I can use a Bitbucket plugin in Jenkins and do the configuration there. Or I can create a webhook in Bitbucket.

I tried both with a great deal of troubleshooting. But neither worked, and there was no error message. I found nothing in the logs. The triggering event clearly happened.