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Install python silently on Windows container and add to PATH

A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another.

In this article we will examine how we can silently install python on a container running windows and add it to path. By doing so we can run python scripts inside our container and perform various tests, or even create webservices that will be hosted as containers inside a Cloud provider.

In order to host python inside a windows system I am using the below Dockerfile. A file named configuration.ps1 could exist inside your building directory and contain other instructions like modules installation. If you do not want this step you can remove the last two lines of the Dockerfile.

 RUN Invoke-WebRequest -UseBasicParsing -OutFile python.exe; `
    Start-Process python.exe -Wait -ArgumentList /PrependPath=1, /quiet; `
    Remove-Item -Force python.exe
COPY ./configuration.ps1 .
CMD .\configuration.ps1

When python is installed inside your container you will need to add it on PATH in order to use the verb python. This is done by appending the installation directory on windows PATH.

In order to do you will need to get an interactive session with your container.

docker exec -it container_name powershell

With the below command you can find where is the python installation located. You will need to change python version to the one that you installed. If you had installed the version 3.5 then you would need to change 3.10 to 3.5.

py -3.10 -c "import sys; print(sys.executable[:-10])"

The last step would be to set this location in the PATH. You can do that using the command below.

setx path "%path%;C:\Users\ContainerAdministrator\AppData\Local\Programs\Python\Python310\"

Then you can just press python and voilà.

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Structure python code with packages – import functions from different files

A modular application is an application composed of loosely coupled, functional units called modules, and these modules can be linked together to form a larger application. When you implement your python applications you should create such structures instead of big monoliths.

In this guide I will demonstrate how you can call python function from different folders and files (called packages). I have created a flask application which has as entrypoint the file.

The solution is structured as shown below. The app folder is the root folder which contains all the code for the application. In the root hierarchy the is placed along with other folders as templates, static and helpers.

As I need to create a helper function that will request data from an external API I created a file named github inside my helpers folder and I defined a function within it.

The function is very simple and returns a simple message. Code for can be found below.

def my_function():
  return "Hello from function"

In order to call your helper functions from your main app or from another python package you should first import package

from helpers import github

and then use the function.

def home():
    return github.my_function()

This code will display on my flask main page the message of the function.

You can perform in such way any other activities by specifying your python file and then the function.