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:

• quay.io/k0sproject/bootloose-alpine3.18
• quay.io/k0sproject/bootloose-alpine3.19
• quay.io/k0sproject/bootloose-amazonlinux2023
• quay.io/k0sproject/bootloose-amazonlinux2
• quay.io/k0sproject/bootloose-clearlinux
• quay.io/k0sproject/bootloose-debian10
• quay.io/k0sproject/bootloose-debian12
• quay.io/k0sproject/bootloose-fedora38
• quay.io/k0sproject/bootloose-rockylinux9
• quay.io/k0sproject/bootloose-ubuntu18.04
• quay.io/k0sproject/bootloose-ubuntu20.04
• quay.io/k0sproject/bootloose-ubuntu22.04

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!

• Customize the OS image
• Run Apache
• Specify which ports on the hosts should be bound to services
• Use Ansible to provision machines
• Run Docker inside bootloose machines!
• Isolation and DNS resolution with custom docker networks
• OpenShift 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:

• Check out the examples.
• File an issue.
• Contact us via the form on the k0sproject website.

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