This guide explains how to create and deploy a simple Go-based HTTP web server. 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-go1.21/ directory:

   git clone https://github.com/unikraft-cloud/examples
   cd examples/httpserver-go1.21/

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-go121:latest
unikraft run --metro fra \
  -m 256M \
  -p 443:8080/tls+http \
  --scale-to-zero policy=on,cooldown-time=1000 \
  --image <my-org>/httpserver-go121:latest

or

Using the legacy kraft CLI

kraft cloud deploy \
  -M 256Mi \
  -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-go121-9a2wv
uuid:         8bb34040-9434-4a28-bd1e-c24ee532e2da
state:        starting
image:        <my-org>/httpserver-go121
resources:
  memory:     256MiB
  vcpus:      1
service:
  uuid:       cc4ed399-32da-eb56-3671-b477108d1040
  name:       red-dew-jtk6yxk1
  domains:
  - fqdn:     red-dew-jtk6yxk1.fra.unikraft.app
networks:
- uuid:       51f79dc1-e989-908d-894b-bdf0a87e7901
  private-ip: 10.0.3.3
  mac:        12:b0:57:91:bb:a5
timestamps:
  created:    just now

or

Using the legacy kraft CLI

[●] Deployed successfully!
 │
 ├───────── name: httpserver-go121-9a2wv
 ├───────── uuid: 8bb34040-9434-4a28-bd1e-c24ee532e2da
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://red-dew-jtk6yxk1.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/httpserver-go121@sha256:b16d61bb7898e764d8c11ab5a0b995e8c25a25b5ff89e161fc994ebf25a75680
 ├─────── memory: 256 MiB
 ├────── service: red-dew-jtk6yxk1
 ├─ private fqdn: httpserver-go121-9a2wv.internal
 └─── private ip: 10.0.3.3

In this case, the instance name is httpserver-go121-9a2wv and the address is https://red-dew-jtk6yxk1.fra.unikraft.app. They're different for each run.

Use curl to query the Unikraft Cloud instance of the Go-based HTTP web server:

curl https://red-dew-jtk6yxk1.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-go121-9a2wv  running  <my-org>/httpserver-go121        256MiB  1      red-dew-jtk6yxk1.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-go121-9a2wv  red-dew-jtk6yxk1.fra.unikraft.app  running  1 minute ago  oci://unikraft.io/<my-org>/httpserver-go121@sha256:...  256 MiB  1            9.32 ms

When done, you can remove the instance:

Using the unikraft CLI (Recommended)

unikraft instances delete httpserver-go121-9a2wv

or

Using the legacy kraft CLI

kraft cloud instance remove httpserver-go121-9a2wv

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

• server.go: the actual Go HTTP server implementation
• Kraftfile: the Unikraft Cloud specification
• Dockerfile: the Docker-specified app filesystem

The following options are available for customizing the app:

• If you only update the implementation in the server.go 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.

• If you add new source code files, build them using the corresponding go build command.

• If you build a new executable, update the cmd line in the Kraftfile and replace /server with the path to the new executable.

• 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.