Fast and Easy Dev Environments with Vagrant and Bash Scripting

Tawanda Eddie Jr.
5 min readApr 29

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Introduction

As developers, one thing we find ourselves frequently doing when working on software projects is setting up development environments. With all the advancements happening in DevOps, we are spoiled for choice when it comes to this. Regardless, setting up an environment can be tedious and time-consuming, especially when you just want to get to work. Oftentimes they require complex OS configuration, software dependencies, and other settings.

We have all probably heard the words “it works on my machine” from a colleague when a program refuses to run. When working as part of a team, we must have consistent development environments that can easily be replicated by everyone. This will ensure that everyone is working with the same set of tools and configurations, thereby reducing the number of variables when we eventually encounter some issues. In this tutorial, we will explore how to use Vagrant and bash scripting to automate the process of creating and configuring a development environment for a simple Flask application. This will help to ensure consistency across development environments and streamline the process of setting up a new development machine.

Requirements

Before we begin, make sure you have the following software installed on your computer:

Background

I’ll start by briefly explaining what Vagrant and bash scripting are and why we will be using them.

Vagrant is an open-source tool that allows you to create and manage virtual machines on your machine. If the goal is to make our development environments as close to production as possible, then Vagrant can help with that. Vagrant makes it easy to set up and configure a production-like environment on your machine, regardless of the operating system. This means that you can use the same tools and workflow in development and production.

But Vagrant alone isn’t enough. We also need a way to ensure that our program’s dependencies are installed correctly and ready to use. This is where bash scripting comes in. Bash scripting is a powerful tool that allows you to automate your tasks and streamline your development process. It’s a command language interpreter used on Linux and Mac systems to perform various tasks, from simple file manipulation to complex system administration tasks. With the help of bash scripting, you can automate repetitive tasks and create a consistent development environment that works on any system.

With these tools, we can easily create, configure, and manage our development environments with confidence that they will be easy to replicate.

Setting Up the Project

Create a new directory for your project and navigate into it:

mkdir myapp
cd myapp

If you’re not using Vagrant and just want to get to the bash scripting you can skip this section

Vagrant Set Up

Create a new Vagrantfile in the project directory. A Vagrantfile is a configuration file that defines the environment that Vagrant is going to set up. It allows you to specify things like the base image to use (known as the box), the number of VMs to create, networking, shared folders, and any provisioning scripts to run. You can use vagrant init to generate the default Vagrantfile, create one from scratch, or use a template. You can create a file called Vagrantfile and copy the one below for this tutorial:

Vagrant.configure("2") do |config|
config.vm.box = "ubuntu/bionic64"
config.vm.network "forwarded_port", guest: 5000, host: 5000
config.vm.synced_folder "/your/local/path/flask-demo", "/home/vagrant/myapp", type: "rsync", rsync__exclude: [".git/"]
config.vm.provider "virtualbox" do |vb|
vb.memory = "1024"
end
config.vm.provision "shell", path: "provision.sh"
end

This Vagrantfile uses an Ubuntu 18.04 base image with 1 CPU and 1024MB of RAM. We will serve our Flask app on port 5000, so we will set up port forwarding between the host and guest. We also configure the shared folder with rsync enabled to allow us to make changes locally and have our changes reflected on the server. We can also exclude some files and folders to avoid syncing unnecessary files. We can specify the provider in the Vagrantfile or pass it as a flag when we run vagrant up. The second option may provide more flexibility. The script will provision the machine using the bootstrap.sh script which we will now proceed to create.

Bash Scripting

Create a new file named bootstrap.sh in the project directory with the following contents:

#!/usr/bin/env bash

# Check if myapp directory exists, and create it if it doesn't
if [ ! -d "/home/vagrant/myapp" ]
then
mkdir /home/vagrant/myapp
fi

cd /home/vagrant/myapp

# Update package manager and install necessary packages
sudo apt-get update
sudo apt-get install -y python3 python3-pip python3-venv

# Create virtual environment
python3 -m venv /home/vagrant/myapp/venv
source /home/vagrant/myapp/venv/bin/activate

# Install Flask and other dependencies
pip install Flask

# Create Flask app
cat <<EOF > /home/vagrant/myapp/src/app.py
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello():
return "Hello World!"
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
EOF

# Change permissions to allow anyone to update the app.py file
sudo chmod 777 /home/vagrant/myapp/src/app.py

# Start the app
nohup python3 /home/vagrant/myapp/src/app.py >/dev/null 2>&1 &
echo "Flask app running on <http://localhost:5000>"

As you can see, the script is easy to understand. The script will first check if the project directory exists, and if it doesn’t then it will be created. After updating the package manager and installing our dependencies, we can create a virtual environment for our app. This is not strictly necessary but it is still a good practice. This allows us to have multiple projects that require different versions of the same dependencies without any problems. The playbook also creates a simple app with a single route that returns the string ‘Hello World’. The script will also update the permissions on our app.py file.

Note that setting permissions to 777 is not advisable in production as it will allow anyone to update the file.

When we run our server, we add the nohup Unix command which allows us to disconnect from the shell session and still have the command continue to run. The & at the end puts the process in the background so that we can continue to use the shell while the process is running.

Run the App

We use the vagrant up command to create and provision the Vagrant environment. This process will download the box if it is not found on your machine and use the bash script to install all dependencies and create our Flask app.

Once the environment is up and running, you can open your browser and navigate to http://localhost:5000. You should see a "Hello World!" message.

Now, you can navigate to the local synced folder, open your app in any text editor of your choice, make some changes, refresh your browser and see the updates immediately.

Conclusion

Congratulations! You have just set up a simple Flask application in a Vagrant environment using a bash script. I hope your Flask application grows into something cool, or you can use what you’ve learned here to create a different script that fits your needs. If you have any thoughts or feedback, you can reach out to me on Twitter. You can also follow my Instagram for more developer content.

This tutorial was originally published on my blog. Check it out for early access to new content.

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Tawanda Eddie Jr.

A Fullstack Engineer seeking truth, wisdom, and, above all, enlightenment where technology and philosophy intersect. | Fiction lover 🌐: www.tawandamunongo.dev