Use Cases

Serverless Databases

Databases are the backbone of modern applications, but they are notoriously resource-hungry, slow to scale, and costly to operate at low utilisation. Traditional VM- or container-based solutions keep idle resources running, resulting in waste and inefficiency. With Unikraft Cloud, serverless databases gain the advantages of unikernels, combining extreme performance with true scale-to-zero efficiency.

Why Run Serverless Databases on Unikraft Cloud?

⚡ Instant Boot, Millisecond Latency

Unikraft unikernels start in milliseconds, enabling databases to scale up instantly when requests arrive and shut down to zero when idle. This ensures resources are used only when needed, without cold-start penalties.

🔒 Stronger Security by Design

Each database instance runs as a specialised, single-process unikernel, drastically reducing the attack surface compared to general-purpose OSes. This isolation protects customer data with built-in, lightweight security.

💰 Cost-Efficient Scale-to-Zero

Unikraft’s unikernel architecture allows serverless databases to consume no resources when idle and scale to thousands of instances under load. You pay only for active queries, making it ideal for spiky workloads, dev/test environments, and SaaS platforms.

🛠 Seamless Serverless Integration

Unikraft Cloud natively supports serverless architectures. Databases can integrate with API gateways, event triggers, and headless services running on Unikraft, forming a fully serverless backend that is fast, elastic, and efficient.

📈 Performance Without Trade-offs

Unlike traditional serverless platforms where databases often suffer from high overhead, unikernel-based instances deliver bare-metal-like throughput and predictable latency, optimised for both OLTP and OLAP workloads.

Getting Started

This guide shows you how to use PostgreSQL, a powerful, open source object-relational database system, in a serverless fashion. With Unikraft Cloud, you can run PostgreSQL in a lightweight virtual machine, with minimal overhead and millisecond fast startup times. The instance will scale-to-zero when not in use.

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/postgres/ directory:

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

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

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# 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:

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kraft cloud deploy -e POSTGRES_PASSWORD=unikraft -p 5432:5432/tls -M 1024 .

The output shows the instance URL and other details:

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[●] Deployed successfully!
 │
 ├────────── name: postgres-saan9
 ├────────── uuid: 3a1371f2-68c6-4187-84f8-c080f2b028ca
 ├───────── state: starting
 ├────────── fqdn: young-thunder-fbafrsxj.fra0.kraft.host
 ├───────── image: postgres@sha256:2476c0373d663d7604def7c35ffcb4ed4de8ab231309b4f20104b84f31570766
 ├──────── memory: 1024 MiB
 ├─────── service: young-thunder-fbafrsxj
 ├── private fqdn: postgres-saan9.internal
 ├──── private ip: 172.16.3.1
 └────────── args: wrapper.sh docker-entrypoint.sh postgres -c shared_preload_libraries='pg_ukc_scaletozero'

In this case, the instance name is postgres-saan9 and the service young-thunder-fbafrsxj. They are different for each run.

If you use port 5432/tls as per the example above you can now directly connect to postgres:

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psql -U postgres -h young-thunder-fbafrsxj.fra0.kraft.host

Use the unikraft password at the password prompt. You should see output similar to:

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Password for user postgres:
psql (15.5 (Ubuntu 15.5-0ubuntu0.23.04.1), server 16.2)
WARNING: psql major version 15, server major version 16.
         Some psql features might not work.
Type "help" for help.

postgres=#

Use SQL and psql commands for your work.

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

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kraft cloud instance list

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NAME              FQDN                                         STATE    CREATED AT     IMAGE                                   MEMORY   ARGS                                      BOOT TIME
postgres-saan9    young-thunder-fbafrsxj.fra0.kraft.host       running  6 minutes ago  postgres@sha256:2476c0373d663d7604d...  1.0 GiB  wrapper.sh docker-entrypoint.sh postgres  603.42 ms

When done, you can remove the instance:

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kraft cloud instance remove postgres-saan9

Using Volumes

You can use volumes for data persistence for you PostgreSQL instance.

For that you would first create a volume:

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kraft cloud volume create --name postgres --size 200

Then start the PostgreSQL instance and mount that volume:

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kraft cloud deploy -e POSTGRES_PASSWORD=unikraft -e PGDATA=/volume/postgres -v postgres:/volume -p 5432:5432/tls -M 1024 .

Customize Your Deployment

Your deployment is a standard PostgreSQL installation. Customizing the deployment generally means providing a different environment.

An obvious one is to use a different database password when starting PostgreSQL. For that you use a different POSTGRES_PASSWORD environment variable when starting the PostgreSQL instance.

You could also a different location to mount your volume or set additional configuration options.

And, of course, you can use the PostgreSQL instance in conjunction with a frontend service, see the guide here. However, in that case make sure to disable scale-to-zero if you plan to use the DB internally.

Learn More

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

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kraft cloud --help

Or visit the CLI Reference.