A Technical I.T./DevOps Blog
Problem scenario
You want to see if there is an operating system, software or host-based firewall on your Linux machine. What do you do?
Solution
Run the following six commands for clues:
sudo ps -ef | grep firewalld
sudo systemctl status firewalld
sudo ps -ef | grep ufw
sudo ufw status
sudo iptables -L #*
sudo nmap -P0 127.0.0.1
If you are running the server in a public cloud,
…
Continue reading “How Do You Tell if There is a Firewall on Linux?”
Problem scenario
You have a multi-node cluster of Hadoop. You want to add a new data node. What do you do?
Solution
1. a) Log into the server that will be the new DataNode. Do these things until you get to step 2.
b) Install Hadoop on the new DataNode. If you do not know how, see this posting.
c)
…
Continue reading “How Do You Add a New Node to a Hadoop Cluster?”
Problem scenario
You have heard about Amazon Elastic Container Registry. You want to configure a Docker registry using an AWS PaaS offering. How do you use ECR?
Solution
1. Log into the AWS web console.
2. Go here: https://console.aws.amazon.com/ecs/home#/repositories
3. Click “Get started” if you have never created a repository before. If you have created a repository, skip to the next step.
4.
…
Problem scenario
You want a process to keep running on a Linux server. But when the user who starts it logs off, the process ends. How do you allow the user to log off but obviate the logging off from terminating (through signaling termination) of that process you want to remain running?
Solution
Have the user use the nohup command to execute the important process.
…
Continue reading “How Do You Prevent a Process from Ending Due to a User Logging Off?”
Problem scenario
You want to test out GitLab. How do you create your first project?
Solution
Prerequisite
This assumes you have GitLab installed; if you do not know how, see this posting.
Procedures
1. Log into GitLab via the web UI. (If you do not have credentials and you set it up, the web UI for GitLab should have prompted you to enter a new password twice.
…
Continue reading “How Do You Create a New Project in GitLab?”
In 2009 the U.S. Congress decided to recognize Data Privacy Day for years in the future (nationaldaycalendar.com). We appreciate a day to promote privacy. We are in the works to support encrypted email on this website.
Data Privacy Day “is celebrated every January 28 and is an international effort to promote the importance of data privacy” (taken from https://www.us-cert.gov/ncas/current-activity/2017/01/24/Data-Privacy-Day-Events). It started when Convention 108 was signed on January 28,
…
Problem scenario
You want to do deploy (install and configure) GitLab on a Debian Linux server. What do you do?
Solution
1. Get a Debian or Ubuntu Linux server with either 3.5 GB of RAM or at least 1.5 GB of RAM and 2 GB of virtual memory. If you need to resize an AWS instance, see this posting. If you need to resize a GCP instance,
…
Continue reading “How Do You Install GitLab on Debian or Ubuntu Linux?”
Problem scenario
You are trying to configure GitLab to work with Jenkins (so the two are integrated to enable CI, continual integration, in your environment). When you test a connection of an integration webhook from GitLab to reach out to Jenkins you receive this error:
“Hook executed successfully but returned HTTP 403… You are authenticated as anonymous Groups that you are in: Permission you need to have (but didn’t) hudson.model.Hudson.Read…which is implied by hudson.security.Permission.GenericRead…”
How do you solve this problem?
…
Problem scenario
You have sufficient hard disk space. But your applications are memory constrained on your Linux server. You cannot add more RAM. How do you create swap space on your Linux server (to create virtual memory)?
Solution
Overview
We consider virtual memory to be a hybrid of RAM “and disk space that running processes can use. Swap space is the portion of virtual memory that is on the hard disk,
…
Continue reading “How Do You Create Swap Space on a Linux Server Running in the Cloud?”
Problem scenario
The needs for a server have changed. You now want your AWS EC-2 virtual server to have more CPU and RAM, but you do not want to migrate to a new instance. You can only afford 15 minutes of down time. What should you do to resize the server’s capacity to have more processors and greater memory?
Solution
These basic steps will work if you want to downgrade your server too (to save money).
…