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KraftCloud

Run a Django App

In this guide we create and deploy a Python Django web application. To run this example, follow these steps:

  1. Install the kraft CLI tool and a container runtime engine, e.g. Docker.

  2. Clone the examples repository and cd into the examples/http-python3.12-django5.0/ directory:

Terminal window
git clone https://github.com/kraftcloud/examples
cd examples/http-python3.12-django5.0/

Make sure to log into KraftCloud by setting your token and a metro close to you. We use fra0 (Frankfurt, 🇩🇪) in this guide:

Terminal window
# Set KraftCloud access token
export KRAFTCLOUD_TOKEN=token
# Set metro to Frankfurt, DE
export KRAFTCLOUD_METRO=fra0

When done, invoke the following command to deploy this application on KraftCloud:

Terminal window
kraft cloud deploy -p 443:80 -M 512 .

The output shows the instance URL and other details:

Terminal window
[●] Deployed successfully!
 │
 ├────────── name: http-python312-django50-vt56c
 ├────────── uuid: d8469447-fdf6-4caf-9fea-494218ca6f72
 ├───────── state: running
 ├─────────── url: https://dawn-sound-n5wrkxi2.fra0.kraft.host
 ├───────── image: http-python312-django50@sha256:221666d414299aff54dbf10020b3d540270ee0c5907c1c6a728ca254ce8b0e50
 ├───── boot time: 80.32 ms
 ├──────── memory: 512 MiB
 ├─ service group: dawn-sound-n5wrkxi2
 ├── private fqdn: http-python312-django50-vt56c.internal
 ├──── private ip: 172.16.6.5
 └────────── args: /usr/bin/python3 /app/main.py

In this case, the instance name is http-python312-django50-vt56c and the URL is https://dawn-sound-n5wrkxi2.fra0.kraft.host. They are different for each run.

Use curl to query the KraftCloud instance of the Django web app server:

Terminal window
curl https://dawn-sound-n5wrkxi2.fra0.kraft.host
<!doctype html>


<html lang="en-us" dir="ltr">
    <head>
        <meta charset="utf-8">
        <title>The install worked successfully! Congratulations!</title>
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <style>
          html {
            line-height: 1.15;
          }
          a {
            color: #19865C;
          }
[...]

Or point a browser at the URL and/or its /admin area. The username and password are set in the Dockerfile (more on this file later) to unikraft/unikraft.

At any point in time, you can list information about the instance:

Terminal window
kraft cloud instance list
NAME                  FQDN                                   STATE    CREATED AT    IMAGE                                                           MEMORY   ARGS                            BOOT TIME
http-python312-ma2i9  young-night-5fpf0jj8.fra0.kraft.host  running  1 minute ago  razvan.unikraft.io/http-python312@sha256:278cb8b14f9faf9c27...  512 MiB  /usr/bin/python /src/server.py  15094us

When done, you can remove the instance:

Terminal window
kraft cloud instance remove http-python312-django50-vt56c

Customize your Application

To customize the application, update the files in the repository, listed below:

  • main.py: the entry point for the app
  • Kraftfile: the KraftCloud specification
  • Dockerfile: the Docker-specified application filesystem
import bjoern
import helloworld.wsgi
import os
from werkzeug.middleware.shared_data import SharedDataMiddleware


app = helloworld.wsgi.application
app = SharedDataMiddleware(app, {
'/static': '/app/static',
})
bjoern.run(app, "0.0.0.0", 80)

Lines in the Kraftfile have the following roles:

  • spec: v0.6: The current Kraftfile specification version is 0.6.

  • runtime: python:3.12: The Unikraft runtime kernel to use is Python 3.12.

  • rootfs: ./Dockerfile: Build the application root filesystem using the Dockerfile.

  • cmd: ["/usr/bin/python3", "/app/main.py"]: Use this as the starting command of the instance.

Lines in the Dockerfile have the following roles:

The following options are available for customizing the application:

  • If only updating the implementation in the main.py source file, no other change is required.

  • If new files are added, these have to be copied in the application filesystem, using the COPY command in the Dockerfile.

  • If a new Python source files is added, update the cmd line in the Kraftfile and replace server.py to run that file when creating the instance.

  • More extensive changes may require expanding the Dockerfile with additional Dockerfile commands. This includes the use of Python frameworks and the use of pip, as shown in the next section.

Using pip

pip is a package manager for Python. It is used to install dependencies for Python applications. pip uses the requirements.txt file to list required dependencies (with versions).

The http-python3.12-flask3.0 guide details the use of pip to deploy an application using the Flask framework on KraftCloud.

Run the command below to deploy the application on KraftCloud:

Terminal window
kraft cloud deploy -p 443:80 -M 512 .

Differences from the Django app are also the steps required to create an pip-based app:

  1. Add the requirements.txt file used by pip.

  2. Add framework-specific source files. In our case, this means the server.py file.

  3. Update the Dockerfile to:

    1. COPY the local files.

    2. RUN the pip3 install command to install dependencies.

    3. COPY of the resulting and required files (/usr/local/lib/pyhon3.12 and server.py) in the application filesystem, using the scratch container.

The files are listed below:

flask>=3.0,<3.1

The requirements.txt file lists the flask dependency.

The Kraftfile is the same one used for Django.

For Dockerfile newly added lines have the following roles:

  • FROM python:3.12-bookworm AS base: Use the base image of the python:3.12-bookworm container. This provides the pip3 binary and other Python-related components. Name the current image base.

  • WORKDIR /app: Use /app as working directory. All other commands in the Dockerfile run inside this directory.

  • COPY requirements.txt /app: Copy the package configuration file to the Docker filesystem.

  • RUN pip3 install ...: Install pip components listed in requirements.txt.

  • COPY --from=base ...: Copy generated Python files in the new base image in the scratch-based image.

Similar actions are required for other pip3-based applications. See also the http-python3.12-django5.0 example.

Learn More

Use the --help option for detailed information on using KraftCloud:

Terminal window
kraft cloud --help

Or visit the CLI Reference.