A Technical I.T./DevOps Blog
Problem Scenario
In AWS you try to delete a Security Group. You cannot do it because you get an error that “These security groups are associated with one or more network interfaces. Delete the network interfaces, or associate them with different security groups.” You click the link “View your network interfaces.” But you are unable to delete the network interfaces. You try to “Detach” them (with the “Force detachment” option),
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Problem scenario
You are trying to run a Docker command, but you get this error:
Error parsing reference: ” continual/integration” is not a valid repository/tag.
What do you do?
Solution
Look to see if you have an extra “\” or space in your Docker run command. That can cause this problem.
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Continue reading “How Do You Troubleshoot the Docker Command Error “not a valid repository/tag”?”
Updated on 9/24/19
Problem scenario
You want to install Elastic Stack on different distributions of Linux with the same exact script. What should you do?
Solution
Prerequisites
i. You should have at least 3 GB of total memory (a combination of virtual memory and RAM) allocated to the server. If you need to add memory,
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Continue reading “How Do You Install the Elastic Stack on Any Type of Linux?”
Problem scenario
You receive this message “PHP Parse error: syntax error, unexpected end of file in /path/to/file.php on line x.” How do you solve this?
Solution
Verify you have a closing brace for every open brace. You may want to go to this site to help you find an unmatched brace.
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Continue reading “How Do You Troubleshoot the PHP Syntax Error “unexpected end of file in …”?”
Problem scenario
You try to run SonarScanner or do something with SonarQube. You get a “500 Error” or some related internal server error. What should you do?
Solution
Reinstall Java. It is a dependency for SonarQube. You can keep SonarQube installed and just stop the services while you uninstall and reinstall Java. After you remove Java (and do research if you don’t know how), you can use this
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Continue reading “How Do You Troubleshoot a “500 Error” with SonarQube?”
Problem scenario
You know that the orchestrated installation of interconnected systems can have a significant benefit. Sometimes ordering the installation of packages on a single server can be useful. You do not want a “failed to connect to server” or “ansible ssh shared connection failed” message when you run a playbook. You want the playbook run to wait for the server to boot up again. The playbook reboots multiple servers at once.
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Problem scenario
When you logged into the web UI for Jira you saw one or more error messages. How do you find out of the error is still valid?
You want to find the web UI page in Jira that will tell you about the health of the cluster for one of the following error categories:
-Supported platforms
-Database
-File system
-Indexing
-Attachments
-Cluster
-Secondary Storage
Where do you go to view the status of detected problems or potentially detected problems?
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Continue reading “How Do You Find the Health Status of a Jira Cluster in the Web UI?”
Problem scenario
You have a long-running process that seems to not be progressing. The problem is reoccurring. How do you troubleshoot it?
Possible solution #1
Start a duplicate terminal session. Use “sudo ps -evf | grep foobar” where “foobar” is the name of the process. Try the “top” command to see if the are memory or CPU constraints.
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Continue reading “How Do You Troubleshoot a Process in Linux That Seems to Hang Forever?”
Problem scenario
You try to start the NFS service with a command like this: sudo systemctl start nfs.service
However you get an error like this: “Failed to start nfs.service: Transaction order is cyclic. See system logs for details. See system logs and ‘systemctl status nfs.service’ for details.”
Possible Solution #1
Modify the /etc/fstab file. Is it corrupt? You may need to remove recently added entries and reboot the server.
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Continue reading “How Do You Troubleshoot the NFS Message About “Transaction order is cyclic”?”
Problem scenario
You inherited code from a different programmer. You want to test out an object. How do you create an object of a pre-made class?
Solution
Look at how many variables the class has. Take this code for example:
class Cartesian(object):
def __init__(self,a = 0,b = 0):
self.a = a
self.b = b
def distance(self):
return (self.a**2 + self.b**2) ** 0.5 # Pythagorean theorem. …
Continue reading “How Do You Instantiate a class in Python?”