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This is a common template or interface for you to start building your own nabla container image.

Check out nabla containers and in particular runnc.

How to

In order to build a docker image for nabla containers, we have to build:

  • the nabla toolstack
  • the unikernel image
  • the docker image

Build the nabla toolstack

There's an informative blog post on how to build the nabla rumprun toolstack here. If you clone a more recent branch, the process should be as easy as the following:

git clone
git submodule update --init
. obj/

and you should end up with the toolstack (${ARCH}-rumprun-netbsd-) in your PATH variable.

Alternatively you can use one of the (unofficial) docker images with the toolstack embedded at /usr/local:

You can run these containers using the following command:

docker run --runtime=runc --rm -v ${PWD}:/build -it cloudkernels/debian-rumprun-build:${ARCH} /bin/bash

where ${ARCH} could be x86_64 or aarch64.

Build the unikernel Image

building the image is as easy as running the following:

${ARCH}-rumprun-netbsd-gcc myprog.c -o myprog-rumprun
rumprun-bake solo5-spt myprog.spt myprog-rumprun

So we have ourselves an .spt file (a unikernel). To try it out, assuming you have a solo5-spt binary lying around you can do the following:

solo5-spt ./myprog.spt

Asumming the unikernel image is successful, its time to construct the docker image.

Build the docker image

Rumprun is a quirky unikernel framework, with a number of assumptions we can't ignore. Thus, in order to get the unikernel running correctly when in a nabla container environmnent, we need to be careful and include the correct stubs for a dummy root filesystem. So, clone this repo, which contains the basic rootfs from rumprun's lib/librumprunfs_base/rootfs, and a template Dockerfile shown below:

FROM scratch
COPY myprog.spt /myprog.nabla
COPY rootfs/etc /etc
ENTRYPOINT [ "myprog.nabla" ]

Copy the spt file in this directory and run:

docker build -f Dockerfile -t myprog-nabla:${ARCH} .

You should end up with a local docker image named myprog-nabla, tagged with your current architecture variant (x86_64 or aarch64).

Assuming you have setup runnc correctly, spawning the container is as easy as:

docker run --rm --runtime=runnc myprog-nabla:${ARCH}
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