`railcar` - rust implementation of the oci-runtime spec

What is `railcar`?

railcar is a rust implementation of the opencontainers initiative's runtime spec. It is similar to the reference implementation runc, but it is implemented completely in rust for memory safety without needing the overhead of a garbage collector or multiple threads. For more information on the development of railcar, check out Building a Container Runtime in Rust

Building `railcar`

Install rust:

curl https://sh.rustup.rs -sSf | sh
cargo install cargo-when
rustup toolchain install stable-x86_64-unknown-linux-gnu
rustup default stable-x86_64-unknown-linux-gnu # for stable
rustup target install x86_64-unknown-linux-musl # for stable
rustup toolchain install nightly-x86_64-unknown-linux-gnu
rustup default nightly-x86_64-unknown-linux-gnu # for nightly
rustup target install x86_64-unknown-linux-musl # for nightly

Building can be done via build.sh:

build.sh

By default, build.sh builds a dynamic binary using gnu. To build a static binary, set TARGET to x86_64-unknown-linux-musl:

TARGET=x86_64-unknown-linux-musl ./build.sh

Build requirements for TARGET=x86_64-unknown-linux-gnu:

libseccomp

Build requirements for TARGET=x86_64-unknown-linux-musl:

git submodule update --init
autotools
make
gcc
musl-gcc

To build a release version:

build.sh --release

If you build using stable instead of nightly, the set_name feature will be disabled and the init process inside the container will not be named rc-init when viewed via ps or /proc/$pid/cmdline.

Using `railcar`

./railcar run

You can specify a different bundle directory where your config.json is located with -b:

./railcar -b /some/other/directory run

Using `railcar` with docker

railcar can be used as a backend for docker. To use it, start the docker daemon with an additional backend:

dockerd ... --experimental --add-runtime "rc=/path/to/railcar"

Then you can use railcar by specifying the rc backend:

docker run -it --rm --runtime rc hello

Note that you should start the daemon with a terminal (the -t option) so that docker can properly collect stdout and stderr from railcar. If you want to daemonize the container, just use:

docker run -dt --rm --runtime rc hello

Differences from `runc`

In general, railcar is very similar to runc, but some of the runc commands are not supported. Currently, railcar does not support the following commands:

 checkpoint
 events
 exec
 init
 list
 pause
 restore
 resume
 spec

Also, railcar always runs an init process separately from the container process.

Contributing

railcar is an open source project. See CONTRIBUTING for details.

Oracle gratefully acknowledges the contributions to railcar that have been made by the community.

License

railcar is dual licensed under the Universal Permissive License 1.0 and the Apache License 2.0.

See LICENSE for more details.

vishvananda/railcar

railcar - rust implementation of the oci-runtime spec

What is railcar?

Building railcar

Using railcar

Using railcar with docker

Differences from runc