A Technical I.T./DevOps Blog
Problem scenario
You want to create files in the /home/ directory of your user. You are getting permission errors in the /home/ directory but the permissions are 777 and you are the user who is the owner of the directory, what should you do?
Possible Solution #1
1. Run this command: sudo service autofs stop
2. Make files or directories in home.
…
Problem scenario
You created some Docker containers and assigned them IP addresses. How do you find out what their IP addresses are?
Solution
1. Run this command: docker ps -a # find the container ID of the container you want to know about
2. Run this command but substitute “container_id” with the container ID you found above:
docker inspect -f ‘{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}’ container_id
…
Continue reading “How Do You Determine the IP Address Assignments of Running Docker Containers?”
Question
Python supports the creation of new threads for [bound or unbound] functions. They can help with multiprocessing. If you want a server to begin certain operations in parallel with others, you may want to use new processes as opposed to new threads. Both threads and processes can provide the same parallel processing benefit. What are some disadvantages of using a thread to call a function?
…
Continue reading “In Python, What Are Some Disadvantages with Calling a Function as a New Thread?”
Problem scenario
You have a monitoring tool on a RedHat Enterprise Linux server that needs to send out emails upon certain events happening. You want to install and configure an email server. You need to send outbound emails, but you do not need to receive inbound emails. How do you configure RHEL to be able to send out regular emails over the internet?
Prerequisite
This assumes that Postfix has been installed.
…
Problem scenario
You try to go to the default Kubernetes web UI (the dashboard), but you are being prompted for a username and password.
Solution
From the server with kubectl, run this:
kubectl config view
…
Continue reading “How Do You Find the Default Kubernetes Web UI Credentials?”
Problem scenario
You want to install pip to work with Python packages and Python features. How do you install this on an Ubuntu or Debian Linux server?
Solution
Run these commands:
sudo apt-get -y update
sudo apt-get -y install python-pip
…
Continue reading “How Do You Install pip on an Ubuntu or Debian Server?”
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.
…
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
…
Continue reading “How Do You Get the mysql Command to Work from an Ubuntu Linux Command Line?”
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.
…
Continue reading “What Do You Do when Cassandra Stalls on “Initializing IndexInfo”?”
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.
…
Continue reading “How Do You Use Terraform to Create a Server in GCP?”