racker 0.3.0

Introduction

Racker is an experimental harness tool for provisioning and launching containers, with a focus on operating system containers.

By a “harness tool”, we mean a combination of image bakery and payload launcher.

• The image bakery is based on modern and generic tools for creating machine images like mkosi and Packer, as well OCI-compliant container images. Container images can be acquired from both vendor- specific and standardized distribution channels like OCI-compliant image registries.

• A payload is any of an interactive command prompt (shell), a single program invocation, or a long-running daemon.

Details

About systemd-nspawn

systemd-nspawn may be used to run a command or OS in a light-weight namespace container. In many ways it is similar to chroot, but more powerful since it fully virtualizes the file system hierarchy, as well as the process tree, the various IPC subsystems and the host and domain name.

It is primarily intended for use in development, experimenting, debugging, instrumentation, testing and building of software.

It can easily be used to start containers capable of booting up a complete and unmodified Linux distribution inside as normal system services.

For learning more details about systemd-nspawn, we strongly recommend to read the more extensive systemd-nspawn in a nutshell.

Racker

The racker program aims to resemble the semantics of Docker by providing a command line interface compatible with the docker command.

# Invoke the vanilla Docker `hello-world` image.
# FIXME: Does not work yet.
# racker run -it --rm hello-world /hello
# racker run -it --rm quay.io/podman/hello

# Acquire rootfs images.
racker pull debian:bullseye-slim
racker pull fedora:37

# Launch an interactive shell.
racker run -it --rm debian:bullseye-slim bash
racker run -it --rm fedora:37 bash
racker run -it --rm docker://registry.access.redhat.com/ubi8/ubi-minimal /bin/bash
racker run -it --rm docker://quay.io/centos/centos:stream9 bash

# Launch a single command.
racker run -it --rm debian:11-slim hostnamectl
racker run -it --rm opensuse/tumbleweed hostnamectl
racker run -it --rm ubuntu:jammy /bin/cat /etc/os-release
racker run -it --rm registry.suse.com/suse/sle15 /bin/cat /etc/os-release
racker run -it --rm registry.suse.com/bci/bci-base:15.4 /bin/cat /etc/os-release
racker run -it --rm docker://ghcr.io/jpmens/mqttwarn-standard /usr/bin/hostnamectl

# Verbose mode.
racker --verbose run -it --rm fedora:37 hostnamectl

# Use stdin and stdout, with timing.
time echo "hello world" | racker run -it --rm fedora:37 cat /dev/stdin > hello
cat hello

Postroj

The idea behind postroj is to provide an entrypoint to a command line interface implementing actions that don’t fit into racker, mostly having a more high-level character.

Currently, postroj pkgprobe implements a flavor of full system integration/acceptance testing in order to test the soundness of actual installed binary distribution packages, in the spirit of autopkgtest.

To do so, it implements the concept of curated operating system images, whose labels have a different layout than labels of Docker filesystem images.

Getting started:

# List available images.
postroj list-images

# Acquire images for curated operating systems.
postroj pull debian-bullseye
postroj pull fedora-37

# Acquire rootfs images for all available distributions.
postroj pull --all

# Run a self test procedure, invoking `hostnamectl` on all containers.
postroj selftest hostnamectl

Package testing:

# Run a self test procedure, invoking example probes on all containers.
postroj selftest pkgprobe

# Run two basic probes on different operating systems.
postroj pkgprobe --image=debian-bullseye --check-unit=systemd-journald
postroj pkgprobe --image=fedora-37 --check-unit=systemd-journald
postroj pkgprobe --image=archlinux-20220501 --check-unit=systemd-journald

# Run probes that need to install a 3rd party package beforehand.

postroj pkgprobe \
    --image=debian-stretch \
    --package=http://ftp.debian.org/debian/pool/main/w/webfs/webfs_1.21+ds1-12_amd64.deb \
    --check-unit=webfs \
    --check-network=http://localhost:8000

postroj pkgprobe \
    --image=debian-bullseye \
    --package=https://dl.grafana.com/oss/release/grafana_8.5.1_amd64.deb \
    --check-unit=grafana-server \
    --check-network=http://localhost:3000

postroj pkgprobe \
    --image=centos-8 \
    --package=https://dl.grafana.com/oss/release/grafana-8.5.1-1.x86_64.rpm \
    --check-unit=grafana-server \
    --check-network=http://localhost:3000