Deploy Memcached

This guide shows you how to use Memcached, an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

To run it, 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/memcached/ directory:

git clone https://github.com/kraftcloud/examples
cd examples/memcached/

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 token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra0

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

kraft cloud deploy -p 11211:11211/tls -M 256 .

The output shows the instance URL and other details:

[●] Deployed successfully!
 │
 ├────────── name: memcached-arkv7
 ├────────── uuid: da436eca-bc64-46d7-a04c-72832652b10e
 ├───────── state: running
 ├────────── fqdn: weathered-smoke-hehsdinv.fra0.kraft.host
 ├───────── image: memcached@sha256:f53cdbce4dc185e8acc8ecb93a0ab0ba99085ca0837a0ad2062aae9e31382e58
 ├───── boot time: 19.27 ms
 ├──────── memory: 256 MiB
 ├─────── service: weathered-smoke-hehsdinv
 ├── private fqdn: memcached-arkv7.internal
 ├──── private ip: 172.16.6.5
 └────────── args: /usr/bin/memcached -u root

In this case, the instance name is memcached-arkv7; it’s different for each run.

To test the deployment, first forward the port with the kraft cloud tunnel command:

kraft cloud tunnel 11211:memcached-arkv7:11211

Now, on a separate console, run the following commands to test that it works (you should see output when incrementing):

telnet 127.0.0.1 11211
set test 0 0 1
0
incr test 1
incr test 1

To exit telnet run:

Ctrl + ]
Ctrl + C

To disconnect, simply kill the tunnel command with ctrl-C

Note

We use kraft cloud tunnel only when a service doesn’t support TLS and is not HTTP-based (we use TLS/SNI to determine the correct instance to send traffic to). Also note that tunnel command is not needed when connecting via an instance’s private IP/FQDN, ie, when a Memcached instance is used as a backend to another instance that acts as a frontend and which does support TLS.

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 TIME
memcached-arkv7  weathered-smoke-hehsdinv.fra0....  running  11 minutes ago  memcached@sha256:f53cdbce4...    256 MiB  /usr/bin/memcached -u root       19266us

When done, you can remove the instance:

kraft cloud instance remove memcached-arkv7

Customize your Application

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

• Kraftfile: the Unikraft Cloud specification, including command-line arguments
• Dockerfile: In case you need to add files to your instance’s rootfs

Kraftfile

spec: v0.6

runtime: memcached:latest

rootfs: ./Dockerfile

cmd: ["/usr/bin/memcached", "-u", "root"]

Dockerfile

FROM debian:bookworm AS build

RUN set -xe; \
    echo "Your code here";

FROM scratch

# Your files here
# COPY --from=build / /

Learn More

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

kraft cloud --help

Or visit the CLI Reference.