Run a Ruby app
In this guide we create and deploy a simple Ruby-based HTTP web server. To run this example, follow these steps:
-
Install the
kraft
CLI tool and a container runtime engine, e.g. Docker. -
Clone the
examples
repository andcd
into theexamples/http-ruby3.2/
directory:
git clone https://github.com/kraftcloud/examplescd examples/http-ruby3.2/
Make sure to log into Unikraft Cloud by setting your token and a metro close to you.
We use fra0
(Frankfurt, 🇩🇪) in this guide:
# Set Unikraft Cloud access tokenexport UKC_TOKEN=token# Set metro to Frankfurt, DEexport UKC_METRO=fra0
When done, invoke the following command to deploy this application on Unikraft Cloud:
kraft cloud deploy -p 443:8080 -M 256 .
The output shows the instance URL and other details:
[●] Deployed successfully! │ ├────────── name: http-ruby32-s6l8n ├────────── uuid: b1ebbbc0-5efa-476c-adb6-99866773245c ├───────── state: running ├─────────── url: https://silent-resonance-1jtz5c66.fra0.kraft.host ├───────── image: http-ruby32@sha256:4cf3b341898e6ebff18ff2b68353ef872dded650c9d16a6f005a8fbe8a7cbb3d ├───── boot time: 71.19 ms ├──────── memory: 256 MiB ├─────── service: silent-resonance-1jtz5c66 ├── private fqdn: http-ruby32-s6l8n.internal ├──── private ip: 172.16.3.3 └────────── args: /usr/bin/ruby /src/server.rb
In this case, the instance name is http-ruby32-s6l8n
and the URL is https://silent-resonance-1jtz5c66.fra0.kraft.host
.
They are different for each run.
Use curl
to query the Unikraft Cloud instance of the Ruby-based HTTP web server:
curl https://silent-resonance-1jtz5c66.fra0.kraft.host
Hello, World!
At any point in time, you can list information about the instance:
kraft cloud instance list
NAME FQDN STATE CREATED AT IMAGE MEMORY ARGS BOOT TIMEhttp-ruby32-s6l8n silent-resonance-1jtz5c66.fra0.kraft.host running 12 minutes ago http-ruby32@sha256:4cf3b341898e6ebff18ff2b68353ef... 256 MiB /usr/bin/ruby /src/server.rb 71191us
When done, you can remove the instance:
kraft cloud instance remove http-ruby32-s6l8n
Customize your Application
To customize the application, update the files in the repository, listed below:
server.rb
: the actual Ruby HTTP serverKraftfile
: the Unikraft Cloud specificationDockerfile
: the Docker-specified application filesystem
require 'socket'
socket = TCPServer.new(8080)
loop do client = socket.accept
request = client.gets
response = "HTTP/1.1 200 OK\r\n" \ "Content-type: text/html\r\n" \ "Connection: close\r\n" \ "\r\n" \ "Hello, World!" client.puts(response)
client.closeend
spec: v0.6
runtime: ruby:3.2
rootfs: ./Dockerfile
cmd: ["/usr/bin/ruby", "/src/server.rb"]
FROM scratch
# Simple Ruby HTTP serverCOPY ./server.rb /src/server.rb
The following options are available for customizing the application:
-
If only updating the implementation in the
server.rb
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 theDockerfile
. -
If a new Ruby source files is added, update the
cmd
line in theKraftfile
and replaceserver.rb
to run that file when creating the instance. -
More extensive changes may require expanding the
Dockerfile
with additionalDockerfile
commands.
Learn More
Use the --help
option for detailed information on using Unikraft Cloud:
kraft cloud --help
Or visit the CLI Reference.