This guide explains how to create and deploy a Python FastAPI web app. To run this example, follow these steps:

1. Install the CLI. Use the unikraft CLI or the legacy kraft CLI. You need a BuildKit builder. The easiest way to get one is via Docker. Alternatively, you can also directly set up and use BuildKit, see the quick start.

   Note: The unikraft CLI is the current standard, while kraft is the legacy version. Choose one of the CLIs below and only run the commands associated with it for the rest of this guide.

2. Clone the examples repository and cd into the examples/httpserver-python3.12-fastapi-0.121.3/ directory:

   git clone https://github.com/unikraft-cloud/examples
   cd examples/httpserver-python3.12-fastapi-0.121.3/

Make sure to log into Unikraft Cloud and pick a metro close to you. This guide uses fra (Frankfurt, 🇩🇪):

Using the unikraft CLI (Recommended)

unikraft login

or

Using the legacy kraft CLI

# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra

When done, invoke the following command to deploy this app on Unikraft Cloud:

Using the unikraft CLI (Recommended)

unikraft build . --output <my-org>/httpserver-python312-fastapi-01213:latest
unikraft run --metro fra \
  -m 512M \
  -p 443:8080/tls+http \
  --scale-to-zero policy=on,cooldown-time=1000 \
  --image <my-org>/httpserver-python312-fastapi-01213:latest

or

Using the legacy kraft CLI

kraft cloud deploy \
  -M 512Mi \
  -p 443:8080/tls+http \
  --scale-to-zero on \
  --scale-to-zero-cooldown 1s \
  .

The output shows the instance address and other details:

Using the unikraft CLI (Recommended)

metro:        fra
name:         httpserver-python312-fastapi-01213-0n84f
uuid:         5d7fc331-3c23-4953-b025-d152a872ea29
state:        starting
image:        <my-org>/httpserver-python312-fastapi-01213
resources:
  memory:     512MiB
  vcpus:      1
service:
  uuid:       ced3df54-64cc-9217-3441-e0b4995319f0
  name:       dry-water-0oexx89g
  domains:
  - fqdn:     dry-water-0oexx89g.fra.unikraft.app
networks:
- uuid:       66d1766f-0a03-8b62-eb1a-0adb09b07b1d
  private-ip: 10.0.1.69
  mac:        12:b0:a1:15:7c:4a
timestamps:
  created:    just now

or

Using the legacy kraft CLI

[●] Deployed successfully!
 │
 ├───────── name: httpserver-python312-fastapi-01213-0n84f
 ├───────── uuid: 5d7fc331-3c23-4953-b025-d152a872ea29
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://dry-water-0oexx89g.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/httpserver-python312-fastapi-01213@sha256:fb2a00dcf1cfc3ac821cbda05f82f38d66e63121344b9bc60c6a6e2f11917b98
 ├─────── memory: 512 MiB
 ├────── service: dry-water-0oexx89g
 ├─ private fqdn: httpserver-python312-fastapi-01213-0n84f.internal
 └─── private ip: 10.0.1.69

In this case, the instance name is httpserver-python312-fastapi-01213-0n84f and the address is https://dry-water-0oexx89g.fra.unikraft.app. They're different for each run.

Use curl to query the Unikraft Cloud instance of the Python FastAPI web app server:

curl https://dry-water-0oexx89g.fra.unikraft.app

{"Hello":"World"}

You can list information about the instance by running:

Using the unikraft CLI (Recommended)

unikraft instances list

METRO  NAME                                      STATE    IMAGE                                        ARGS  MEMORY  VCPUS  FQDN                                 CREATED
fra    httpserver-python312-fastapi-01213-0n84f  standby  <my-org>/httpserver-python312-fastapi-01213        512MiB  1      dry-water-0oexx89g.fra.unikraft.app  2 minutes ago

or

Using the legacy kraft CLI

kraft cloud instance list

NAME                                      FQDN                                 STATE    STATUS   IMAGE                                                                   MEMORY   VCPUS  ARGS  BOOT TIME
httpserver-python312-fastapi-01213-0n84f  dry-water-0oexx89g.fra.unikraft.app  standby  standby  oci://unikraft.io/<my-org>/httpserver-python312-fastapi-01213@sha25...  512 MiB  1            169.45 ms

When done, you can remove the instance:

Using the unikraft CLI (Recommended)

unikraft instances remove httpserver-python312-fastapi-01213-0n84f

or

Using the legacy kraft CLI

kraft cloud instance remove httpserver-python312-fastapi-01213-0n84f

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

• server.py: the entry point for the app
• Kraftfile: the Unikraft Cloud specification
• Dockerfile: the Docker-specified app filesystem

Lines in the Kraftfile have the following roles:

• spec: v0.7: The current Kraftfile specification version is 0.7.

• runtime: base-compat:latest: The Unikraft runtime kernel to use is the latest that provides a minimal Linux-compatible environment.

• rootfs: Build the app root filesystem. source: ./Dockerfile means the filesystem is built using the Dockerfile. format: erofs means the filesystem type is EROFS.

• cmd: ["/usr/bin/python3", "-m", "uvicorn", "src.server:app", "--host", "0.0.0.0", "--port", "8080"]: Use this as the starting command of the instance.

Lines in the Dockerfile have the following roles:

• FROM scratch: Build the filesystem from the scratch container image, to create a base image.

The following options are available for customizing the app:

• If you only update the implementation in the server.py source file, you don't need to make any other changes.

• If you create any new source files, copy them into the app filesystem by using the COPY command in the Dockerfile.

• More extensive changes may require extending the Dockerfile (see Dockerfile syntax reference).

Use the --help option for detailed information on using Unikraft Cloud:

Using the unikraft CLI (Recommended)

unikraft --help

or

Using the legacy kraft CLI

kraft cloud --help

Or visit the CLI Reference or the legacy CLI Reference.