Tag: DevOps

Git: clone succeeded, but checkout failed

Have you ever faced any issues with git clone? Personally, I can’t recall any significant or memorable problems I’ve encountered while cloning remote repositories. Typically, the issues were related to authentication or network connectivity. Therefore, there was nothing particularly special to write about. However, as you work with different environments, the chances of coming across something interesting enough to share increase, even though it might be obvious to some.

Let’s take a simple example: you’re trying to clone an existing repository, which was created by someone else. The repository had already been filled out with files you need. Assuming you have credentials in place, you run git clone <repo’s url> on your Windows machine and get the following:

I hid the error message. I’ll reveal it later

What could go wrong? The cloning process succeeded, indicating that the issue is not related to Git credentials or network connectivity. However, the checkout process failed. What does this mean? It means that if you navigate to the folder of the cloned repository in the explorer, you won’t find any files written to the disk. Now, let me reveal the full error message, which is straightforward:

error: invalid path 'config/app1/application-staging.yml '
fatal: unable to checkout working tree

Found a “root cause”? There is the whitespace at the end of the filename.

However, you may wonder, since the repository was pre-created and used by other people, how did this happen? You’re correct to question that.

The reason is that Windows doesn’t support trailing space characters and automatically removes them when saving a file (you can read more about it here). On the other hand, Linux does support both leading and trailing whitespaces in filenames.

“file1.txt” and “file1.txt ” are two different files actually

Git knows about these limitations and has a special config setting to control it:

core.protectNTFS

If set to true, do not allow checkout of paths that would cause problems with the NTFS filesystem, e.g. conflict with 8.3 “short” names. Defaults to true on Windows, and false elsewhere.

The reason why other people can clone the repo without issues is that core.protectNTFS is set to false (manually or because of underlying OS)

So, to clone the repo on Windows you can use the following command:

get clone -c core.protectNTFS=false <repo url>
and now you can fix the wrong filename and sync with remote repo

As a summary, I would advise all developers and DevOps engineers to strictly avoid using trailing or leading spaces in filenames altogether. By doing so, we can eliminate the potential conflicts and issues that may arise from incompatible behaviors between different operating systems.

Python Coding: FizzBuzz challenge

FizzBuzz is a very common task, asked in Dev/DevOps interviews. You are given a range of numbers and need to write algorithm using the following rules: if the number is divisible by 3, print “Fizz”; if the number is divisible by 5, output “Buzz”; if the number is divisible by both 3 and 5, the result should be “FizzBuzz”.

The main goal of the task is to check how you understand loops, conditionals and simple math using one of programming or scripting languages. I solved the task using PowerShell years ago: check this gist.

As I started to learn Python, I decided to share FizzBuzz implementation in this language to show how simple and “elegant” the solution can be.

I used matplotlib and colorama to make a pie chart and add color text output respectively. Defined a function fizz_buzz with 2 arguments, and then used try/catch/finally statements to catch exceptions errors. Inside of the try, the for loop and if conditionals are described to meet all task’s rules. As a result, the function outputs numbers and categories based on rules, and makes a pie chart to show how many fizz, buzz, fizzbuzz found in percentage. 

import matplotlib.pyplot as plt
import colorama
from colorama import Fore, Back, Style
colorama.init()

def fizz_buzz(x,y):
    """Python version of popular Fizz Buzz task"""
    fb = 0 ; b = 0; f = 0; rest = 0 # start values
    fb_type = ['fizzbuzz','fizz','buzz','rest'] # plot labels
    fb_colors = ['r','y','c','g'] # plot colors
    fb_explode = [0.2, 0.1, 0.1, 0.1] # plot fraction of the radius
    try:
        for n in range(x,y):
            if ((n % 3 == 0) and (n % 5 == 0)):
                fb += 1
                print(Fore.RED + f"Found FizzBuzz: {n}")
            elif n % 3 ==0:
                f += 1
                print(Fore.WHITE + f"Found Fizz: {n}")
            elif n % 5 ==0:
                b += 1
                print(Fore.GREEN + f"Found Buzz: {n}")
            else: 
                rest += 1
                print(Style.BRIGHT + f"The rest is {n}")
            print(Style.RESET_ALL)
        fb_array = [fb, f, b, rest]
        plt.pie(fb_array, colors = fb_colors, explode = fb_explode, shadow = True, radius = 1.1, autopct = '%1.1f%%') # form a pie
        plt.legend(fb_type,loc='upper right') # show legend
        plt.show() # show a pie
    except:
        print(Style.BRIGHT + Fore.RED + "You provided wrong x and y")
        print(Style.RESET_ALL)
    finally:
        print(Style.BRIGHT + Fore.GREEN + "Author: github.com/rlevchenko")
        print(Style.RESET_ALL)

Result

Available at Gist

%d bloggers like this: