crosbymichael / crun

A fast and lightweight fully featured OCI runtime and C library for running containers

crun

A fast and low-memory footprint OCI Container Runtime fully written in C.

crun conforms to the OCI Container Runtime specifications (https://github.com/opencontainers/runtime-spec).

Documentation

The user documentation is available here.

Static build

If you are looking for a static build, take a look at the instructions here.

Why another implementation?

While most of the tools used in the Linux containers ecosystem are written in Go, I believe C is a better fit for a lower level tool like a container runtime. runc, the most used implementation of the OCI runtime specs written in Go, re-execs itself and use a module written in C for setting up the environment before the container process starts.

crun aims to be also usable as a library that can be easily included in programs without requiring an external process for managing OCI containers.

Performance

crun is faster than runc and has a much lower memory footprint.

This is the elapsed time on my machine for running sequentially 100 containers, the containers run /bin/true:

	crun	runc	%
100 /bin/true (no network namespace)	0:05.70	0:10.95	-47.9%
100 /bin/true (new network namespace)	0:06.16	0:11.17	-44.8%

Build

On Fedora these dependencies are required for the build:

dnf install -y make python git gcc automake autoconf libcap-devel \
    systemd-devel yajl-devel libseccomp-devel libselinux-devel \
    go-md2man glibc-static python3-libmount libtool

On Ubuntu:

apt-get install -y make git gcc build-essential pkgconf libtool \
   libsystemd-dev libcap-dev libseccomp-dev libyajl-dev libselinux1-dev \
   go-md2man libtool autoconf python3

Unless you are also building the Python bindings, Python is needed only by libocispec to generate the C parser at build time, it won't be used afterwards.

Once all the dependencies are installed:

./autogen.sh && ./configure
make
sudo make install