Deploying a Flask Application on AWS EC2

In this blog post, we will walk through the process of deploying a Flask application on an AWS EC2 instance. We will cover each step from setting up the environment to configuring Nginx as a reverse proxy. By following these steps, you will be able to successfully deploy your Flask application and make it accessible to the outside world.

Step 1: Update the System

To ensure that our system has the latest package information, run the following command:

sudo apt-get update
sudo apt-get update
sudo apt-get update

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This command updates the package lists for upgrades and new installations.

Step 2: Install Python Virtual Environment

To create an isolated Python environment for our project, we need to install the python3-venv package. Execute the following command:

sudo apt-get install python3-venv
sudo apt-get install python3-venv
sudo apt-get install python3-venv

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Python virtual environments allow us to manage dependencies and isolate our project’s environment from the system Python installation.

Step 3: Clone or Create the Project Directory

You have two options here. Either clone an existing project from GitHub using the git clone command, or create a new project directory using the mkdir command followed by the desired project name.

Step 4: Navigate to the Project Directory

Change your current working directory to the project directory using the cd command:

cd project_name
cd project_name
cd project_name

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Step 5: Create a Virtual Environment

Now, let’s create a virtual environment for our project. Execute the following command:

python3 -m venv venv
python3 -m venv venv
python3 -m venv venv

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This command creates a virtual environment named “venv” inside your project directory.

Step 6: Activate the Virtual Environment

To activate the virtual environment, run the following command:

. venv/bin/activate
. venv/bin/activate
. venv/bin/activate

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Once activated, your command prompt will reflect the virtual environment’s name.

Step 7: Install Flask and Dependencies

Next, we need to install Flask and any other project dependencies. Use either of the following commands:

pip install -r requirements.txt
pip install -r requirements.txt
pip install -r requirements.txt

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or

pip install Flask
pip install Flask
pip install Flask

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The first command is used if you have a requirements.txt file listing all the dependencies. The second command installs Flask directly.

Step 8: Run the Flask Application

To ensure everything is working correctly, run the Flask application using the following command:

python app.py
python app.py
python app.py

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This command starts the Flask development server, allowing you to test your application locally.

Step 9: Install Gunicorn

Gunicorn is a production-ready web server for running Flask applications. Install it using the following command:

pip install gunicorn
pip install gunicorn
pip install gunicorn

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Step 10: Run Gunicorn

To run your Flask application with Gunicorn, execute the following command:

gunicorn -b 0.0.0.0:8000 app:app
gunicorn -b 0.0.0.0:8000 app:app
gunicorn -b 0.0.0.0:8000 app:app

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This command starts Gunicorn, binding it to all available network interfaces on port 8000.

Step 11: Create a Systemd Service File

To run the Flask application as a service, create a systemd service file using the following command:

sudo nano /etc/systemd/system/project_name.service
sudo nano /etc/systemd/system/project_name.service
sudo nano /etc/systemd/system/project_name.service

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Step 12: Add Code to the Service File

Inside the service file, add the following code:

[Unit]
Description=Gunicorn instance for a simple app
After=network.target
[Service]
User=ubuntu
Group=www-data
WorkingDirectory=/home/ubuntu/project_name
ExecStart=/home/ubuntu/project_name/venv/bin/gunicorn -b localhost:8000 app:app
Restart=always
[Install]
WantedBy=multi-user.target
[Unit]
Description=Gunicorn instance for a simple app
After=network.target

[Service]
User=ubuntu
Group=www-data
WorkingDirectory=/home/ubuntu/project_name
ExecStart=/home/ubuntu/project_name/venv/bin/gunicorn -b localhost:8000 app:app
Restart=always

[Install]
WantedBy=multi-user.target
[Unit]
Description=Gunicorn instance for a simple app
After=network.target

[Service]
User=ubuntu
Group=www-data
WorkingDirectory=/home/ubuntu/project_name
ExecStart=/home/ubuntu/project_name/venv/bin/gunicorn -b localhost:8000 app:app
Restart=always

[Install]
WantedBy=multi-user.target

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This code specifies the service description, user, group, working directory, and the Gunicorn command to start the Flask application.

Step 13: Reload Systemd Daemon

After creating the service file, reload the systemd daemon to make it aware of the new service:

sudo systemctl daemon-reload
sudo systemctl daemon-reload
sudo systemctl daemon-reload

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Step 14: Start the Service

To start the Flask application service, run the following command:

sudo systemctl start project_name
sudo systemctl start project_name
sudo systemctl start project_name

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Step 15: Enable the Service on System Startup

To ensure that the Flask application service starts automatically on system boot, execute the following command:

sudo systemctl enable project_name
sudo systemctl enable project_name
sudo systemctl enable project_name

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Step 16: Test the Application

To verify if the Flask application is running correctly, use the curl command to send a request to the local server:

curl localhost:8000
curl localhost:8000
curl localhost:8000

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If everything is set up properly, you should see the response from your Flask application.

Step 17: Install Nginx

To set up Nginx as a reverse proxy, install it using the following command:

sudo apt-get install nginx
sudo apt-get install nginx
sudo apt-get install nginx

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Step 18: Start Nginx

To start the Nginx service, run the following command:

sudo systemctl start nginx
sudo systemctl start nginx
sudo systemctl start nginx

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Step 19: Enable Nginx on System Startup

To ensure that Nginx starts automatically on system boot, execute the following command:

sudo systemctl enable nginx
sudo systemctl enable nginx
sudo systemctl enable nginx

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Step 20: Configure Nginx

Open the Nginx configuration file using the nano editor:

sudo nano /etc/nginx/sites-available/default
sudo nano /etc/nginx/sites-available/default
sudo nano /etc/nginx/sites-available/default

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Step 21: Add Upstream and Proxy Pass

Add the following code at the top of the file, below the default comments:

upstream flaskhelloworld {
    server 127.0.0.1:8000;
}
upstream flaskhelloworld {
    server 127.0.0.1:8000;
}
upstream flaskhelloworld {
    server 127.0.0.1:8000;
}

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Step 22: Configure Proxy Pass

Inside the location / block, add the following code:

location / {
    proxy_pass http://project_name;
}
location / {
    proxy_pass http://project_name;
}
location / {
    proxy_pass http://project_name;
}

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This code sets up the reverse proxy to forward requests to the Gunicorn server running on port 8000.

Step 23: Restart Nginx

To apply the Nginx configuration changes, restart the Nginx service:

sudo systemctl restart nginx
sudo systemctl restart nginx
sudo systemctl restart nginx

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Congratulations! You have successfully deployed a Flask application on an AWS EC2 instance using Gunicorn and Nginx as a reverse proxy. Your Flask application is now accessible through the Nginx server, providing a robust and scalable setup for your application.

原文链接：Deploying a Flask Application on AWS EC2