Troubleshooting Dockerized Blog

This blog is a dockerized WordPress blog. I noticed that my blog site was down this morning. I couldn’t even ssh into the host. I thought it was hacked somehow. After poking it around, I got it back up and running. Here is the things I did to get it back up.

  1. When I did ping hayato-iriumi.net, I got response back.
  2. After a while, I could hit the website but it wasn’t connecting to the database.
  3. I couldn’t even ssh into the host, so I restarted it.
  4. I was able to ssh into it now, so I checked the running containers with the following command.
    docker ps -a
  5. I noticed that NGINX container was failing because it could not start because port 80 was already in use.
  6. Checked which process was using port 80 with the following command.
    sudo netstat -pna | grep 80
  7. It turned out that another instance of NGINX was hogging the port. I stopped it and disabled it with the following command.
    sudo systemctl stop nginx
    sudo systemctl disable nginx
    sudo apt remove nginx
  8. I’m not sure what installed the instance of NGINX.
  9. Restarted the host.
  10. The site came back up.

I am seeing some errors in journalctl so something else may have caused the issue. This is a very common troubleshooting for Linux users but you should know where to look to troubleshoot Linux hosted service. I may rebuild this blog host again just in case it might have been hacked.

Advanced map with Python

As I was writing Python code using map, I came across an issue. When I ran the following code, I came across an error.

import unittest


class test(unittest.TestCase):
    def func1(self, x, y):
        return x ** y

    def test_map(self):
        a = [1, 2, 3, 4]
        results = map(self.func1, a, 2)
        print(results)

I basically wanted to pass 2 for the y parameter of func1 instead of another list. Here is the error I got.

FAILED (errors=1)

Error
Traceback (most recent call last):
  File "C:\Users\hiriu\dev\hoge\test.py", line 10, in test_map
    results = map(self.func1, a, 2)
TypeError: 'int' object is not iterable

Right, the number 2 is not a collection and is not iterable. How do I solve this problem? I searched the web and I found the following solution.

import unittest
import functools

class test(unittest.TestCase):
    def func1(self, x, y):
        return x ** y

    def test_map(self):
        a = [1, 2, 3, 4]
        results = map(functools.partial(self.func1, y=2), a)
        print(list(results))

By using the functools.partial, you get to pass a fixed value to the portion of the function. Here is the output.

[1, 4, 9, 16]

Process finished with exit code 0

Update:

I found an easier way to map a fixed parameter. Here is the example. It’s more readable and maintainable.

import unittest
from itertools import repeat


class test(unittest.TestCase):
    def func1(self, x, y):
        return x ** y

    def test_map(self):
        a = [1, 2, 3, 4]
        results = map(self.func1, a, repeat(2))
        print(list(results))