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<!-- SPDX-FileCopyrightText: 2019 Weaveworks Ltd. SPDX-FileCopyrightText: 2023 bootloose authors SPDX-License-Identifier: Apache-2.0 -->

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bootloose

bootloose creates containers that look like virtual machines. Those containers run systemd as PID 1 and a ssh daemon that can be used to login into the container. Such "machines" behave very much like a VM, it's even possible to run dockerd in them.

bootloose can be used for a variety of tasks, wherever you'd like virtual machines but want fast boot times or need many of them. An easy way to think about it is: Vagrant, but with containers.

bootloose in action:

$ bootloose config create --replicas 3
$ bootloose create
INFO[0000] Pulling image: quay.io/k0sproject/bootloose-ubuntu20.04 ...
INFO[0007] Creating machine: cluster-node0 ...
INFO[0008] Creating machine: cluster-node1 ...
INFO[0008] Creating machine: cluster-node2 ...
$ docker ps
CONTAINER ID    IMAGE                                     COMMAND         NAMES
04c27967f76e    quay.io/k0sproject/bootloose-ubuntu20.04  "/sbin/init"    cluster-node2
1665288855f6    quay.io/k0sproject/bootloose-ubuntu20.04  "/sbin/init"    cluster-node1
5134f80b733e    quay.io/k0sproject/bootloose-ubuntu20.04  "/sbin/init"    cluster-node0
$ bootloose ssh root@node1
[root@1665288855f6 ~]# █

Attribution

This project is a continuation of Footloose by Weaveworks. We are grateful for their work and contributions from the community.

Install

Homebrew

Install using Homebrew package manager:

brew install k0sproject/tap/bootloose

From source

Build and install bootloose from source. It requires having go >= 1.21 installed:

go install github.com/k0sproject/bootloose@latest

Usage

bootloose reads a description of the Cluster of Machines to create from a file, by default named bootloose.yaml. An alternate name can be specified on the command line with the --config option or through the BOOTLOOSE_CONFIG environment variable.

The config command helps with creating the initial config file:

# Create a bootloose.yaml config file. Instruct we want to create 3 machines.
bootloose config create --replicas 3

Start the cluster:

$ bootloose create
INFO[0000] Pulling image: quay.io/k0sproject/bootloose-debian12 ...
INFO[0007] Creating machine: cluster-node0 ...
INFO[0008] Creating machine: cluster-node1 ...
INFO[0008] Creating machine: cluster-node2 ...

It only takes a second to create those machines. The first time create runs, it will pull the docker image used by the bootloose containers so it will take a tiny bit longer.

SSH into a machine with:

$ bootloose ssh root@node1
[root@1665288855f6 ~]# ps fx
  PID TTY      STAT   TIME COMMAND
    1 ?        Ss     0:00 /sbin/init
   23 ?        Ss     0:00 /usr/lib/systemd/systemd-journald
   58 ?        Ss     0:00 /usr/sbin/sshd -D
   59 ?        Ss     0:00  \_ sshd: root@pts/1
   63 pts/1    Ss     0:00      \_ -bash
   82 pts/1    R+     0:00          \_ ps fx
   62 ?        Ss     0:00 /usr/lib/systemd/systemd-logind

Choosing the OS image to run

bootloose will default to running an Ubuntu LTS container image. The --image argument of config create can be used to configure the OS image. OS images provided by this repository are:

The tag :latest is updated when any of the images are changed in the repository. When bootloose CLI binary releases are published, images at that point are tagged with a version that you can pin a config to, such as quay.io/k0sproject/bootloose-ubuntu20.04:v0.7.0.

For example:

bootloose config create --replicas 3 --image quay.io/k0sproject/bootloose-debian12

bootloose config create --replicas 3 --image quay.io/k0sproject/bootloose-debian12:v0.7.0

Some images may need the --privileged flag.

bootloose.yaml

bootloose config create creates a bootloose.yaml configuration file that is then used by subsequent commands such as create, delete or ssh. If desired, the configuration file can be named differently and supplied with the -c, --config option.

$ bootloose config create --replicas 3
$ cat bootloose.yaml
cluster:
  name: cluster
  privateKey: cluster-key
machines:
- count: 3
  spec:
    image: quay.io/k0sproject/bootloose-debian12
    name: node%d
    portMappings:
    - containerPort: 22

This configuration can naturally be edited by hand. The full list of available parameters are in the reference documentation.

Examples

Interesting things can be done with bootloose!

Under the hood

Under the hood, Container Machines are just containers. They can be inspected with docker:

$ docker ps
CONTAINER ID    IMAGE                                  COMMAND         NAMES
04c27967f76e    quay.io/k0sproject/bootloose-debian12  "/sbin/init"    cluster-node2
1665288855f6    quay.io/k0sproject/bootloose-debian12  "/sbin/init"    cluster-node1
5134f80b733e    quay.io/k0sproject/bootloose-debian12  "/sbin/init"    cluster-node0

The container names are derived from cluster.name and cluster.machines[].name.

They run systemd as PID 1, it's even possible to inspect the boot messages:

$ docker logs cluster-node1
systemd 219 running in system mode.
Detected virtualization docker.
Detected architecture x86-64.

Welcome to CentOS Linux 7 (Core)!

Set hostname to <1665288855f6>.
Initializing machine ID from random generator.
Failed to install release agent, ignoring: File exists
[  OK  ] Created slice Root Slice.
[  OK  ] Created slice System Slice.
[  OK  ] Reached target Slices.
[  OK  ] Listening on Journal Socket.
[  OK  ] Reached target Local File Systems.
         Starting Create Volatile Files and Directories...
[  OK  ] Listening on Delayed Shutdown Socket.
[  OK  ] Reached target Swap.
[  OK  ] Reached target Paths.
         Starting Journal Service...
[  OK  ] Started Create Volatile Files and Directories.
[  OK  ] Started Journal Service.
[  OK  ] Reached target System Initialization.
[  OK  ] Started Daily Cleanup of Temporary Directories.
[  OK  ] Reached target Timers.
[  OK  ] Listening on D-Bus System Message Bus Socket.
[  OK  ] Reached target Sockets.
[  OK  ] Reached target Basic System.
         Starting OpenSSH Server Key Generation...
         Starting Cleanup of Temporary Directories...
[  OK  ] Started Cleanup of Temporary Directories.
[  OK  ] Started OpenSSH Server Key Generation.
         Starting OpenSSH server daemon...
[  OK  ] Started OpenSSH server daemon.
[  OK  ] Reached target Multi-User System.

FAQ

Is bootloose just like LXD?

In principle yes, but it will also work with Docker container images and on MacOS as well.

Help

We are a very friendly community and love questions, help and feedback.

If you have any questions, feedback, or problems with bootloose:

bootloose follows the CNCF Code of Conduct. Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting a bootloose project maintainer.