---
title: Containerize a Python application
linkTitle: Containerize your app
weight: 10
keywords: python, flask, containerize, initialize
description: Learn how to containerize a Python application.
aliases:
  - /language/python/build-images/
  - /language/python/run-containers/
  - /language/python/containerize/
  - /guides/language/python/containerize/
---

## Prerequisites

- You have installed the latest version of [Docker Desktop](/get-started/get-docker.md).
- You have a [Git client](https://git-scm.com/downloads). The examples in this section use a command-line based Git client, but you can use any client.

## Overview

This section walks you through containerizing and running a Python application.

## Get the sample application

The sample application uses the popular [FastAPI](https://fastapi.tiangolo.com) framework.

Clone the sample application to use with this guide. Open a terminal, change directory to a directory that you want to work in, and run the following command to clone the repository:

```console
$ git clone https://github.com/estebanx64/python-docker-example && cd python-docker-example
```

## Initialize Docker assets

Now that you have an application, you can create the necessary Docker assets to
containerize your application. You can use Docker Desktop's built-in Docker Init
feature to help streamline the process, or you can manually create the assets.

{{< tabs >}}
{{< tab name="Use Docker Init" >}}

Inside the `python-docker-example` directory, run the `docker init` command. `docker
init` provides some default configuration, but you'll need to answer a few
questions about your application. For example, this application uses FastAPI to
run. Refer to the following example to answer the prompts from `docker init` and
use the same answers for your prompts.

Before editing your Dockerfile, you need to choose a base image. You can use the [Python Docker Official Image](https://hub.docker.com/_/python),  
or a [Docker Hardened Image (DHI)](https://hub.docker.com/hardened-images/catalog/dhi/python).

Docker Hardened Images (DHIs) are minimal, secure, and production-ready base images maintained by Docker.  
They help reduce vulnerabilities and simplify compliance. For more details, see [Docker Hardened Images](/dhi/).

```console
$ docker init
Welcome to the Docker Init CLI!

This utility will walk you through creating the following files with sensible defaults for your project:
  - .dockerignore
  - Dockerfile
  - compose.yaml
  - README.Docker.md

Let's get started!

? What application platform does your project use? Python
? What version of Python do you want to use? 3.12
? What port do you want your app to listen on? 8000
? What is the command to run your app? python3 -m uvicorn app:app --host=0.0.0.0 --port=8000
```


Create a file named `.gitignore` with the following contents.

```text {collapse=true,title=".gitignore"}
# Byte-compiled / optimized / DLL files
__pycache__/
*.py[cod]
*$py.class

# C extensions
*.so

# Distribution / packaging
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
share/python-wheels/
*.egg-info/
.installed.cfg
*.egg
MANIFEST

# Unit test / coverage reports
htmlcov/
.tox/
.nox/
.coverage
.coverage.*
.cache
nosetests.xml
coverage.xml
*.cover
*.py,cover
.hypothesis/
.pytest_cache/
cover/

# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
__pypackages__/

# Environments
.env
.venv
env/
venv/
ENV/
env.bak/
venv.bak/
```

{{< /tab >}}
{{< tab name="Using the official Docker image" >}}

If you don't have Docker Desktop installed or prefer creating the assets
manually, you can create the following files in your project directory.

Create a file named `Dockerfile` with the following contents.

```dockerfile {collapse=true,title=Dockerfile}
# syntax=docker/dockerfile:1

# Comments are provided throughout this file to help you get started.
# If you need more help, visit the Dockerfile reference guide at
# https://docs.docker.com/go/dockerfile-reference/

# Want to help us make this template better? Share your feedback here: https://forms.gle/ybq9Krt8jtBL3iCk7

# This Dockerfile uses Docker Hardened Images (DHI) for enhanced security.
# For more information, see https://docs.docker.com/dhi/
ARG PYTHON_VERSION=3.12
FROM python:${PYTHON_VERSION}-slim

# Prevents Python from writing pyc files.
ENV PYTHONDONTWRITEBYTECODE=1

# Keeps Python from buffering stdout and stderr to avoid situations where
# the application crashes without emitting any logs due to buffering.
ENV PYTHONUNBUFFERED=1

WORKDIR /app

# Create a non-privileged user that the app will run under.
# See https://docs.docker.com/go/dockerfile-user-best-practices/
ARG UID=10001
RUN adduser \
    --disabled-password \
    --gecos "" \
    --home "/nonexistent" \
    --shell "/sbin/nologin" \
    --no-create-home \
    --uid "${UID}" \
    appuser

# Download dependencies as a separate step to take advantage of Docker's caching.
# Leverage a cache mount to /root/.cache/pip to speed up subsequent builds.
# Leverage a bind mount to requirements.txt to avoid having to copy them into
# into this layer.
RUN --mount=type=cache,target=/root/.cache/pip \
    --mount=type=bind,source=requirements.txt,target=requirements.txt \
    python -m pip install -r requirements.txt

# Switch to the non-privileged user to run the application.
USER appuser

# Copy the source code into the container.
COPY . .

# Expose the port that the application listens on.
EXPOSE 8000

# Run the application.
CMD ["python3", "-m", "uvicorn", "app:app", "--host=0.0.0.0", "--port=8000"]
```

Create a file named `compose.yaml` with the following contents.

```yaml {collapse=true,title=compose.yaml}
# Comments are provided throughout this file to help you get started.
# If you need more help, visit the Docker Compose reference guide at
# https://docs.docker.com/go/compose-spec-reference/

# Here the instructions define your application as a service called "server".
# This service is built from the Dockerfile in the current directory.
# You can add other services your application may depend on here, such as a
# database or a cache. For examples, see the Awesome Compose repository:
# https://github.com/docker/awesome-compose
services:
  server:
    build:
      context: .
    ports:
      - 8000:8000
```

Create a file named `.dockerignore` with the following contents.

```text {collapse=true,title=".dockerignore"}
# Include any files or directories that you don't want to be copied to your
# container here (e.g., local build artifacts, temporary files, etc.).
#
# For more help, visit the .dockerignore file reference guide at
# https://docs.docker.com/go/build-context-dockerignore/

**/.DS_Store
**/__pycache__
**/.venv
**/.classpath
**/.dockerignore
**/.env
**/.git
**/.gitignore
**/.project
**/.settings
**/.toolstarget
**/.vs
**/.vscode
**/*.*proj.user
**/*.dbmdl
**/*.jfm
**/bin
**/charts
**/docker-compose*
**/compose.y*ml
**/Dockerfile*
**/node_modules
**/npm-debug.log
**/obj
**/secrets.dev.yaml
**/values.dev.yaml
LICENSE
README.md
```

Create a file named `.gitignore` with the following contents.

```text {collapse=true,title=".gitignore"}
# Byte-compiled / optimized / DLL files
__pycache__/
*.py[cod]
*$py.class

# C extensions
*.so

# Distribution / packaging
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
share/python-wheels/
*.egg-info/
.installed.cfg
*.egg
MANIFEST

# Unit test / coverage reports
htmlcov/
.tox/
.nox/
.coverage
.coverage.*
.cache
nosetests.xml
coverage.xml
*.cover
*.py,cover
.hypothesis/
.pytest_cache/
cover/

# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
__pypackages__/

# Environments
.env
.venv
env/
venv/
ENV/
env.bak/
venv.bak/
```

{{< /tab >}}
{{< tab name="Using Docker Hardened Image" >}}

Docker Hardened Images (DHIs) are available for Python in the [Docker Hardened Images catalog](https://hub.docker.com/hardened-images/catalog/dhi/python). Docker Hardened Images are freely available to everyone with no subscription required. You can pull and use them like any other Docker image after signing in to the DHI registry. For more information, see the [DHI quickstart](/dhi/get-started/) guide.

1. Sign in to the DHI registry:

   ```console
   $ docker login dhi.io
   ```

2. Pull the Python DHI (check the catalog for available versions):

   ```console
   $ docker pull dhi.io/python:3.12.12-debian13-fips-dev
   ```

Create a file named `Dockerfile` with the following contents.

```dockerfile {collapse=true,title=Dockerfile}
# syntax=docker/dockerfile:1

# Comments are provided throughout this file to help you get started.
# If you need more help, visit the Dockerfile reference guide at
# https://docs.docker.com/go/dockerfile-reference/

# Want to help us make this template better? Share your feedback here: https://forms.gle/ybq9Krt8jtBL3iCk7

# This Dockerfile uses Docker Hardened Images (DHI) for enhanced security.
# For more information, see https://docs.docker.com/dhi/
ARG PYTHON_VERSION=3.12.12-debian13-fips-dev
FROM dhi.io/python:${PYTHON_VERSION}

# Prevents Python from writing pyc files.
ENV PYTHONDONTWRITEBYTECODE=1

# Keeps Python from buffering stdout and stderr to avoid situations where
# the application crashes without emitting any logs due to buffering.
ENV PYTHONUNBUFFERED=1

#Add dependencies for adduser
RUN apt update -y && apt install adduser -y

WORKDIR /app

# Create a non-privileged user that the app will run under.
# See https://docs.docker.com/go/dockerfile-user-best-practices/
ARG UID=10001
RUN adduser \
    --disabled-password \
    --gecos "" \
    --home "/nonexistent" \
    --shell "/sbin/nologin" \
    --no-create-home \
    --uid "${UID}" \
    appuser

# Download dependencies as a separate step to take advantage of Docker's caching.
# Leverage a cache mount to /root/.cache/pip to speed up subsequent builds.
# Leverage a bind mount to requirements.txt to avoid having to copy them into
# into this layer.
RUN --mount=type=cache,target=/root/.cache/pip \
    --mount=type=bind,source=requirements.txt,target=requirements.txt \
    python -m pip install -r requirements.txt

# Switch to the non-privileged user to run the application.
USER appuser

# Copy the source code into the container.
COPY . .

# Expose the port that the application listens on.
EXPOSE 8000

# Run the application.
CMD ["python3", "-m", "uvicorn", "app:app", "--host=0.0.0.0", "--port=8000"]
```

Create a file named `compose.yaml` with the following contents.

```yaml {collapse=true,title=compose.yaml}
# Comments are provided throughout this file to help you get started.
# If you need more help, visit the Docker Compose reference guide at
# https://docs.docker.com/go/compose-spec-reference/

# Here the instructions define your application as a service called "server".
# This service is built from the Dockerfile in the current directory.
# You can add other services your application may depend on here, such as a
# database or a cache. For examples, see the Awesome Compose repository:
# https://github.com/docker/awesome-compose
services:
  server:
    build:
      context: .
    ports:
      - 8000:8000
```

Create a file named `.dockerignore` with the following contents.

```text {collapse=true,title=".dockerignore"}
# Include any files or directories that you don't want to be copied to your
# container here (e.g., local build artifacts, temporary files, etc.).
#
# For more help, visit the .dockerignore file reference guide at
# https://docs.docker.com/go/build-context-dockerignore/

**/.DS_Store
**/__pycache__
**/.venv
**/.classpath
**/.dockerignore
**/.env
**/.git
**/.gitignore
**/.project
**/.settings
**/.toolstarget
**/.vs
**/.vscode
**/*.*proj.user
**/*.dbmdl
**/*.jfm
**/bin
**/charts
**/docker-compose*
**/compose.y*ml
**/Dockerfile*
**/node_modules
**/npm-debug.log
**/obj
**/secrets.dev.yaml
**/values.dev.yaml
LICENSE
README.md
```

Create a file named `.gitignore` with the following contents.

```text {collapse=true,title=".gitignore"}
# Byte-compiled / optimized / DLL files
__pycache__/
*.py[cod]
*$py.class

# C extensions
*.so

# Distribution / packaging
.Python
build/
develop-eggs/
dist/
downloads/
eggs/
.eggs/
lib/
lib64/
parts/
sdist/
var/
wheels/
share/python-wheels/
*.egg-info/
.installed.cfg
*.egg
MANIFEST

# Unit test / coverage reports
htmlcov/
.tox/
.nox/
.coverage
.coverage.*
.cache
nosetests.xml
coverage.xml
*.cover
*.py,cover
.hypothesis/
.pytest_cache/
cover/

# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
__pypackages__/

# Environments
.env
.venv
env/
venv/
ENV/
env.bak/
venv.bak/
```

{{< /tab >}}
{{< /tabs >}}

You should now have the following contents in your `python-docker-example`
directory.

```text
├── python-docker-example/
│ ├── app.py
│ ├── requirements.txt
│ ├── .dockerignore
│ ├── .gitignore
│ ├── compose.yaml
│ ├── Dockerfile
│ └── README.md
```

To learn more about the files, see the following:

- [Dockerfile](/reference/dockerfile.md)
- [.dockerignore](/reference/dockerfile.md#dockerignore-file)
- [.gitignore](https://git-scm.com/docs/gitignore)
- [compose.yaml](/reference/compose-file/_index.md)

## Run the application

Inside the `python-docker-example` directory, run the following command in a
terminal.

```console
$ docker compose up --build
```

Open a browser and view the application at [http://localhost:8000](http://localhost:8000). You should see a simple FastAPI application.

In the terminal, press `ctrl`+`c` to stop the application.

### Run the application in the background

You can run the application detached from the terminal by adding the `-d`
option. Inside the `python-docker-example` directory, run the following command
in a terminal.

```console
$ docker compose up --build -d
```

Open a browser and view the application at [http://localhost:8000](http://localhost:8000).

To see the OpenAPI docs you can go to [http://localhost:8000/docs](http://localhost:8000/docs).

You should see a simple FastAPI application.

In the terminal, run the following command to stop the application.

```console
$ docker compose down
```

For more information about Compose commands, see the [Compose CLI
reference](/reference/cli/docker/compose/).

## Summary

In this section, you learned how you can containerize and run your Python
application using Docker.

Related information:

- [Docker Compose overview](/manuals/compose/_index.md)

## Next steps

In the next section, you'll take a look at how to set up a local development environment using Docker containers.