Adventures in Machine Learning

Deploying Machine Learning Models Using Flask: A Step-by-Step Guide

Deploying ML Models using Flask

Machine learning (ML) models are essential tools for data analysts and machine learning enthusiasts. After youve created and trained an ML model, the next step is to deploy the model in a way that it can easily interface with other systems and components.

Application Programming Interfaces (APIs) are used for this purpose, and Flask is a popular web framework used to build APIs. Flask is a Python-based library that provides rich functionality for building web applications. In this article, well explore how to deploy ML models using Flask.

Well start by providing an introduction to deployment and Flask, before proceeding to the various steps involved in deploying the ML model. This guide is aimed at learners who have some basic knowledge of Python programming, ML algorithms, and TensorFlow.

What is Deployment? Deployment refers to the process of making a program or application accessible to end-users.

In the context of machine learning, deployment involves operationalizing the ML model so that it can be accessed by other applications. In simpler terms, it means making the model available for use by others.

What is Flask? Flask is a micro web framework thats used to develop web applications in Python.

Its widely used in the industry because its easy to use, flexible, and lightweight. Flask allows you to create web applications that serve RESTful APIs seamlessly.

Steps to Deploy ML Models using Flask

The process of deploying an ML model using Flask can be broken down into the following four steps. 1.

Getting Your Model Ready

Before deploying your model, its essential to ensure that its been optimized for deployment. One way to do this is to convert it into a format that can be easily interpreted by other systems.

You can save a TensorFlow model as a `.pb` file. This file contains the weights and biases of the trained neural network.

Its also crucial to determine the input and output formats of the model. You need to know the number of input features and the number of output predictions.

This information will be useful when designing your workflow. 2.

Designing our Workflow

A workflow is a series of steps that you need to follow when deploying a Flask API. You need to define the different stages of the process and assign the tasks to different team members.

The workflow should be structured in such a way that its easy to understand and follow.


Coding the Flask API

This step involves writing the code for the Flask API. You need to create a new Python file and import the required libraries.

You then load the TensorFlow model from the `.pb` file, define the input and output formats, and create a new Flask instance. Next, you need to define a new endpoint that will handle incoming requests.

You can use the `@app.route` decorator to create a new endpoint. In the endpoint function, you can accept the incoming data, preprocess it (if necessary), and pass it to the TensorFlow model.

Finally, you return the predictions in the required format. 4.

Running the App

The last step is to run the Flask application. You need to specify the host and the port number on which the application will run.

You can then test the application using a tool like Postman.


In summary, Flask makes it easy to deploy ML models as RESTful APIs. During this process, you need to ensure that your TensorFlow model is saved in the right format and that you know the input and output formats. You also need to design a workflow that defines the different stages of the project and assigns tasks to different team members.

Finally, you write the code for the Flask API and run the application. Flask is a valuable tool to deploy your ML models and can help you build robust, reliable applications.

Designing Our Workflow

Deployment is a critical stage in machine learning development, and it is essential to have a well-structured workflow to ensure that the process is seamless and efficient. A proposed machine learning workflow consists of the following key stages;


Data Acquisition – In this stage, data is collected from various sources. The data is manipulated and validated before it’s fed into the machine learning model for training.

2. Data Preparation – During this stage, data cleaning, feature engineering, and data decomposition are performed.

3. Training and Evaluation – Here is where machine learning models are developed and trained.

The model is then evaluated to determine its accuracy. 4.

Model Deployment – This involves making the trained machine learning model available to end-users. 5.

Monitoring and Performance Improvement – In this stage, performance metrics are collected, and the machine learning model is optimized for performance improvement. A well-designed workflow is critical to ensure that the results achieved are replicable and reliable.

Developing a workflow or process flowchart is an essential step that helps make the process of deploying an ML model using Flask, quick, and efficient. The flowchart is a visual representation of the different steps of the workflow, showing how the tasks are interconnected.

Flowchart Summary

The flowchart is an integral part of the machine learning development process. It helps teams to keep track of the different tasks involved in the process.

Flowcharts explain processes in a simple, unambiguous manner, and their visual representation can save the developing team a lot of time by reducing the need for written documentation. Using a flowchart to create a workflow for deploying an ML model using Flask has several benefits, including:

Easier collaboration between team members

Clarification of roles and responsibilities

Better communication among team members

It’s easier for team members to track progress

Helps identify bottlenecks in the process

Coding the Flask API

Coding a Flask API involves importing required libraries, creating the Flask app, setting up the image upload folder, loading the model, and creating a REST API for the app.

Import Statements

To get started with coding a Flask API, the first step is to import the necessary libraries. These include the Flask library, Tensorflow library, and libraries used for image processing.

Create Flask App

Once the libraries are imported, the Flask application is created. The `app` object is an instance of the Flask class, and `__name__` specifies the name of the app’s module or package.

Setting Up Image Upload Folder

Image upload is a crucial step that allows end-users to upload images to the Flask API. Setting up the image upload folder is done using the `os` and `flask` libraries.

You need to specify the path to the folder where the images will be uploaded.

Loading The Model

Loading the trained machine learning model is a crucial step to making it available for deployment. This step is performed using the Tensorflow library.

You need to specify the path where the model is saved, and the `tf.saved_model.load()` function is used to load the model.

REST API For The App

Creating a REST API for the Flask app involves defining the API endpoint, setting the allowed HTTP methods, and defining the logic that will be executed when the API endpoint is called. In the endpoint function, you need to handle the data, validate it, and pass it to the loaded ML model for prediction.

Finally, you return the predictions in the required format, which can be in JSON.


Developing a well-structured workflow is essential for successful machine learning model deployment. The workflow should be accompanied by a flowchart, which helps teams visualize the different steps involved in the process.

Coding the Flask API requires importing the necessary libraries, creating the Flask app, setting up the image upload folder, loading the model, and creating a REST API for the app. With a clearly defined workflow and well-documented code, deploying ML models using Flask becomes a seamless and efficient process.

Running the App

After setting up and coding the Flask API, the next step is to run the app. This step involves getting the server up and running and uploading an image for testing purposes.

Get the Server Up and Running

To get the server up and running, open a terminal window and navigate to the directory containing the Flask app. Next, you need to set the Flask environment variables, which can be done using the following commands:



export FLASK_ENV=development


Once the environment variables have been set, you can run the app by typing the following command:


flask run


This command will start the Flask server and run the app on a local development server. By default, the app will run on port 5000.

Uploading an Image

After running the app, you can upload an image to test the endpoint. You can do this using the Postman application or through a web interface.

To test the POST endpoint, you need to select POST as the request type and specify the URL for the endpoint.

Once you have specified the URL, select the `Body` tab and choose the `form-data` option.

Next, you need to specify the key-value pair for the image. The key should be `image`, and the value should be the path to the image you want to upload.

After specifying the key-value pair, click the `Send` button to make the POST request. If the request is successful, you should receive a response containing the model’s prediction for the uploaded image.

Deploying Machine Learning Models on a Local Machine

Deploying machine learning models on a local machine can be a great option for small-scale applications with low traffic. There are several ways to deploy machine learning models on a local machine, including using Flask, Django, Docker, or virtual machines.

To deploy a machine learning model on a local machine using Flask, you need to write code to create an API that interfaces with the model. The Flask API can be run on the local machine, and it will allow the model to be accessed by other applications.

Flask makes it easy to create robust, scalable APIs that can handle a variety of requests.

Running the App 24×7

Running the app 24×7 means that the application is always available to end-users, regardless of the time or day. To achieve this, you need to host the app on a server that is accessible over the internet.

Several cloud hosting providers, including Amazon Web Services (AWS) and Microsoft Azure, can be used to host Flask applications. Hosting Flask apps on these platforms involves deploying the app to a remote machine that can be accessed over the internet.

You can also use a platform like Heroku to deploy and host Flask applications. Heroku is a cloud platform that provides a simple way to deploy, manage, and scale applications.

It supports a wide range of programming languages, including Python.

Deployment of Code to a Server

Deployment of code to a server involves transferring the app code to a remote machine over a network. Once the code has been deployed, it can be run on the remote machine using the command line or a web interface.

To deploy a Flask app on a remote machine, you need to have access to the server and perform the following steps:

1. Install the necessary dependencies – This may include Python and other libraries used in the app.

2. Transfer the code to the server – This can be done using FTP, SSH, or Git.

3. Install and configure the WSGI server – The WSGI server is used to interface with the Flask app and manage incoming requests.

4. Start the app – Once everything is set up, you can start the app using the appropriate command.

In conclusion, deploying a machine learning model using Flask involves designing a workflow, coding the Flask API, running the app, and deploying the code to a server. Running the app can be achieved by getting the server up and running and uploading an image for testing purposes.

Flask is a great option for deploying machine learning models on a local machine and can be hosted on a cloud hosting platform for 24×7 availability. Deployment of code to a server requires transferring the code to a remote machine, installing dependencies, configuring the WSGI server, and starting the app.

This article explored the process of deploying machine learning (ML) models using Flask and outlined the necessary steps. We discussed how to prepare the model, design the workflow, code the Flask API, and run the app for testing purposes.

We also highlighted deploying the app on a local machine, running the app 24×7, and deploying the app to a server. Deploying ML models can be challenging, but Flask makes it easier by providing tools to create robust APIs. The takeaways from this article include the importance of a well-structured workflow and using a flowchart to simplify the deployment process.

Additionally, running the app and deploying the code to a server were discussed, emphasizing the importance of accessibility. By deploying ML models using Flask, developers can build efficient, reliable, and scalable web applications.

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