A Technical I.T./DevOps Blog
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?”
Problem scenario
You try to use rsync or you use Ansible’s synchronize module. It fails with this message: “rsync mkdir failed… rsync error in rsync protocol data stream (code 12)”
Solution
Is the destination directory writable? Verify that the destination exists and has the correct permissions for being able to write to it with the user the Ansible playbook uses.
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Problem scenarios
One or both of the following applies to your situation:
#1 In Linux you try to move a directory that is not read only (e.g., its permissions are rwxrwxrwx or 777). You get an error about it being read-only. Your user is the owner of the directory.
OR
#2 You are running an Ansible playbook and trying to change the attributes of the file.
…
Problem scenario
You run an Ansible playbook. You receive an error about the SSL certificate not being valid. What should you do to get the playbook to transfer a file from a website using SSL or TLS to a managed node?
Possible Solution #1
If the problem pertains to retrieving a file from a website URL, this may apply. If the problem is between the managed node and the website and not between the control node and the website,
…
Continue reading “How Do You Solve an Ansible Problem about an SSL Certificate Error?”
Problem scenario
In Linux in the /dev/ directory you looked for the camera. In /dev/ and could not find a file associated with your web camera. You verified the locally attached camera is connected via a USB cable to your physical computer.
When you try to use it, you see this message:
“— Opening /dev/video0…
stat: No such file or directory”
What should you do?
…
Continue reading “What Should You Do When Linux Is Not Finding Your USB Camera?”
Problem scenario
A Jira deployment is failing. The web services are listening on port 8080 or whichever port you configured. But the web UI does not load. What should you do?
Solution
Root cause: “…JIRA is not designed to import data from a new version into an older version.” taken from Atlassian’s website.
Has the database been used in the past?
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Problem scenario
Elasticsearch works but Kibana does not work. You are using a command to start kibana but you get a warning about kibana-monitoring and a cluster_block_exception error being blocked by service unavailable. What should you do?
Possible Solution
Reboot the server.
…
Continue reading “How Do You Troubleshoot Kibana Not Working Correctly?”
Problem scenario
You are trying to connect to a PostgreSQL database. Your database username and password are not working, but you think they should. You get the message: “postgresql.Driver Connection error: org.postgresql.util.PSQLException Fatal: Ident authentication failed for user”
What should you do?
Possible solution #1
Make sure the pg_hba.conf file is configured correctly.
Here is an example if you are trying to connect from your local machine and you do not need your Postgres instance extremely hardened:
# TYPE
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Problem scenario
You run “sudo systemctl start sonar”, but you get this message: “Failed to start sonar.service: Unit not found”
What should you do?
Solution
Run this: sudo systemctl enable sonar
Now you should be able to run your command to start the “sonar” service.
…
Continue reading “How Do You Troubleshoot “Failed to start sonar.service: Unit not found” Error?”
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… No valid crumb was included in the request.”
What should you do?
Solution
Possible solution #1
Warning: This is not a recommended practice.
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