A Technical I.T./DevOps Blog
Problem scenario
You want to write a Python program to display the instance IDs of virtual servers in AWS. What do you do?
Solution
Prerequisites
This assumes you have installed Boto3. If you do not know how, see this posting. This assumes that you are running it on a server that has access to AWS (e.g., it has access to the internet).
…
Continue reading “How Do You Find the Instance Ids of Virtual Servers in AWS Using Python?”
Problem scenario
You save a file in vi. When you go to exit you get the error “E138: Can’t write viminfo file /home/cooluser/.viminfo!”
The error appears to be benign. You can just press ENTER to continue. But you would rather not do this.
What should you do?
Solution
Find the group that this user should be associated with (e.g.,
…
Problem scenario
You are running SonarQube. The service seems to start (based on the output of “sudo systemctl status sonar”). But based on an nmap command on your server’s external IP address, you see no service is listening. You go to the logs directory and cannot find the ce.log file. You cannot reach the web UI for SonarQube. How do you fix this problem?
Possible Solution #1
Look at your sonar.properties file.
…
Problem scenario
You run “kubectl top pod” but you receive an error such as this:
‘Metrics not available or pod default/kubia-xxx-bmb, age: 1hr10m… error: Metrics not available for pod default/kubia-xxx-bmb, age: 1hr10m”‘
What should you do?
Updated on 9/2/19.
Solution
Wait five minutes. Then re-run this command: kubectl top pod
The source of this question and answer were taken from page 432 of Kubernetes in Action by Marko Luksa published in 2018 by Manning.
…
Problem scenario
You run ansible-playbook on a playbook (e.g., .yaml file) that uses a role. It fails with the message “ERROR! the role was not found”. How do you correct this problem?
Solution
Find the ansible.cfg file. Look at the roles_path stanza. Add or modify the path that you want Ansible to look at for a role every time the Ansible playbook runs.
…
Continue reading “How Do You Troubleshoot the Ansible Message “ERROR! the role was not found”?”
Problem scenario
You want to try out Memcached. How do you install memcached and php-memcached to test it?
Solution
(These directions were based on ServerMom.org directions.)
1. Run these commands:
sudo apt-get -y update
sudo apt -y install memcached php-memcached php7.0 apache2 # apache2 is not necessary but useful for testing purposes
2.
…
Continue reading “How Do You Install Memcached on an Ubuntu Server?”
Problem scenario
Someone was doing a web conference and modified several files. You have forgotten what files she modified. How do you find the files that were modified most recently on a Linux server?
Solution
Run this command:
find $1 -type f -exec stat –format ‘%Y :%y %n’ “{}” \; | sort -nr | cut -d: -f2- | head
#
…
Continue reading “How Do You Find the Most Recently Modified Files in Linux?”
Problem scenario
You compile a C program (with gcc foobar.cc) but you get an error message like this:
“foofbar1.cc:71…: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘int’ [-Wformat=]
printf (“y is a %s\n”, y);
^ “
What do you do to not get this error?
Solution
While the code compiles, the executable may not run.
…
Problem scenario
You have installed Ansible and configured it to work with other servers (managed nodes). You want to write an Ansible playbook that will work with Linux managed nodes with three requirements:
1. Transfer a compressed file from a web sever without wget.
2. Uncompress a .zip file without unzip.
3. Work without passwordless SSH authentication to the managed nodes.
How do you accomplish this with using Ansible-supported features?
…
Question
What is GitOps?
Answer
GitOps is a declarative method of managing infrastructure that is driven by committing code into a version control system. GitOps is an indirect, and usually imperative, approach to systems administration that gives a detailed history of past operations. GitOps is the practice of adding code to a Git repository to trigger an operational event (such as rebooting a server, creating a user account,
…