Docker Post-6 Step-by-step guide to create your first Docker file with a Python script

Docker makes it easy to package and deploy applications. If you're new to Docker, here's a simple guide on how to create your first Docker file, which runs a Python script (`hello.py`). This post will cover setting up the Docker file, creating a basic Python script, and handling dependencies through a `requirements.txt` file.

1. Create the Python script `hello.py`

This script is very simple and prints out a message:

Post 5: Mounting Multiple Directories to a Single Container Directory Using Docker Run and Symlink

In this post, we will walk through the steps of mounting multiple directories to a single container directory using Docker and symbolic links (symlinks). This can be particularly useful when you need to access the same directory from different paths within your containerized environment.

Step 1: Create the Root Directory

First, you need to create a root directory that will be shared across the symlinks.

For example, let's create a directory named `root_dir1`:

mkdir root_dir1 

Step 2: Create Symlink Directories

Now that we have the root directory, we'll create multiple symlink directories that will all point to the same root directory. Below are instructions for both **Linux Ubuntu** and **Windows PowerShell** users.

For Linux Ubuntu Users:

Use the `ln -s` command to create symbolic links to the root directory:

ln -s /mnt/c/Users/vikik/Projects/PyProjects/root_dir1 sym1

ln -s /mnt/c/Users/vikik/Projects/PyProjects/root_dir1 sym2

ln -s /mnt/c/Users/vikik/Projects/PyProjects/root_dir1 sym3

For Windows PowerShell Users:

Use the `New-Item` command to create symbolic links in PowerShell:

New-Item -ItemType SymbolicLink -Path "sym1" -Target "root_dir1"

New-Item -ItemType SymbolicLink -Path "sym2" -Target "root_dir1"

New-Item -ItemType SymbolicLink -Path "sym3" -Target "root_dir1"

In both cases, `sym1`, `sym2`, and `sym3` will all point to the `root_dir1` directory.

Step 3: Create and Run a Python Docker Container

Now, let's create a Python container and mount the root directory (`root_dir1`) to the container's `/app` path.

Command to Run the Container:

docker run -d --name my-python-container -v C:\Users\vikik\Projects\PyProjects\root_dir1:/app python sleep infinity

This command runs a Python container in detached mode with the root directory mounted to the `/app` path inside the container.

Access the Container:

To access the container, execute the following:

docker exec -it my-python-container /bin/bash

Once inside the container, update the package manager and install the `nano` text editor:

apt update

apt install nano

Now, create a Python script inside the container:

nano test.py

Step 4: Test the Symlink Folders

Any file you create in the root directory (such as `test.py`) will be accessible in all the symlink folders (`sym1`, `sym2`, and `sym3`) since they all point to the same directory.

For example, if you add code to `test.py` in the `/app` directory, it will also appear in `sym1`, `sym2`, and `sym3`.

This setup allows you to mount multiple directories to the same container directory using Docker, while maintaining flexibility with symlinks.

Conclusion

By following these steps, you can successfully create multiple symlink directories that all point to the same root directory inside a Docker container. This approach is helpful when managing multiple access points to a shared directory within a containerized environment.

Post Reference: Vikram Aristocratic Elfin Share