GitHub - dlespiau/footloose: Container Machines - Containers that look like Virt...
source link: https://github.com/dlespiau/footloose
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README.md
footloose
footloose is a developer tool creating 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 :)
footloose in action:
footloose can be used for a variety of tasks, wherever you'd like virtual
machines but don't want to wait for them to boot or need many of them. An
easy way to think about it is: Vagrant, but
with containers.
Install
footloose binaries can be downloaded from the release page:
# For Linux
curl -Lo footloose https://github.com/dlespiau/footloose/releases/download/0.1.0/footloose-0.1.0-linux-x86_64
chmod +x footloose
sudo mv footloose /usr/local/bin/
# For macOS
curl -Lo footloose https://github.com/dlespiau/footloose/releases/download/0.1.0/footloose-0.1.0-darwin-x86_64
chmod +x footloose
sudo mv footloose /usr/local/bin/
Alternatively, build and install footloose from sources. It requires having
go >= 1.11 installed:
go get github.com/dlespiau/footloose
Usage
footloose reads a description of the Cluster of Machines to create from a
file, by default named Footloose. The config command helps with creating the
initial config file:
# Create a Footloose config file. Instruct we want to create 3 machines instead # of the default, 1. footloose config create --replicas 3
Start the cluster of 3 machines:
$ footloose create INFO[0000] Pulling image: quay.io/footloose/centos7 ... 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
createruns, it will pull the docker image used by thefootloosecontainers so it will take a tiny bit longer.
SSH into a machine with:
$ footloose 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
footloose.yaml
footloose config create creates a footloose.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.
$ footloose config create --replicas 3 $ cat footloose.yaml cluster: name: cluster privateKey: cluster-key machines: - count: 3 spec: image: quay.io/footloose/centos7 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 footloose!
Running dockerd in Container Machines
To run dockerd inside a docker container, two things are needed:
- Run the container as privileged (we could probably do better! expose capabilities instead!).
- Mount
/var/lib/dockeras volume, here an anonymous volume. This is because of a limitations of what you can do with the overlay systems docker is setup to use.
cluster: name: cluster privateKey: cluster-key machines: - count: 1 spec: image: quay.io/footloose/centos7 name: node%d portMappings: - containerPort: 22 privileged: true volumes: - type: volume destination: /var/lib/docker
You can then install and run docker on the machine:
$ footloose create $ footloose ssh root@node0 # yum install -y docker iptables [...] # systemctl start docker # docker run busybox echo 'Hello, World!' Hello, World!
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/footloose/centos7 "/sbin/init" cluster-node2 1665288855f6 quay.io/footloose/centos7 "/sbin/init" cluster-node1 5134f80b733e quay.io/footloose/centos7 "/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.
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