Boot2Docker is a lightweight Linux distribution made specifically to run Docker containers. It runs completely from RAM, is a small ~24MB download and boots in ~5s (YMMV).
- Kernel 4.1.13 with AUFS, Docker v1.9.1 - using libcontainer
- Container persistence via disk automount on
/var/lib/docker
- SSH keys persistence via disk automount
Note: Boot2Docker uses port 2376, the registered IANA Docker SSL port
Boot2Docker is currently designed and tuned for development. Using it for any kind of production workloads at this time is highly discouraged.
Installation instructions for OS X and Windows are available on the Docker documentation site.
The ISO can be downloaded here.
We have built installers for OS
X and
Windows which will
install the boot2docker
management tool, VirtualBox, and any tools needed to
run Boot2Docker.
If you have the prerequisites, or want to help develop Boot2Docker, you can also
download the appropriate boot2docker management
release and use it to
download
boot2docker.iso
.
The boot2docker
management tool leverages VirtualBox's VBoxManage
to
initialise, start, stop and delete the VM right from the command line.
$ boot2docker init
$ boot2docker up
$ boot2docker stop
$ boot2docker download
$ boot2docker up
If your Boot2Docker virtual machine was created prior to 0.11.1-pre1, it's recommended that you
delete - boot2docker delete
and then create a new
VM - boot2docker init
.
The main change is the addition of a /var/lib/boot2docker/userdata.tar
file that is
un-tarred into the /home/docker
directory on boot. This file contains
.ssh/authorized_keys
and .ssh/authorized_keys2
files containing a public
SSH key.
To save and share container images, automate workflows, and more sign-up for a free Docker Hub account.
See Frequently asked questions for more details.
The bootup script output is logged to /boot.log
, so you can see (and
potentially debug) what happens. Note that this is not persistent between boots
because we're logging from before the persistence partition is mounted (and it
may not exist at all).
The latest version of boot2docker
sets up two network adaptors, one using NAT
to allow the VM to download images and files from the internet, and a host only
network that Docker container's ports will be exposed on.
If you run a container with an exposed port, and then use OSX's open
command:
$ boot2docker up
$ eval "$(boot2docker shellinit)"
$ docker run --name nginx-test -d -p 80:80 nginx
$ open http://$(boot2docker ip 2>/dev/null)/
$ docker stop nginx-test
$ docker rm nginx-test
The eval "$(boot2docker shellinit)"
sets the DOCKER_HOST
environment variable for
this shell, then the docker run
starts the webserver as a daemon, and open
will then show the default page in your default web browser (using boot2docker ip
).
If you want to share container ports with other computers on your LAN, you will need to set up NAT adaptor based port forwarding.
If you need to customize the options used to start the Docker daemon, you can
do so by adding entries to the /var/lib/boot2docker/profile
file on the
persistent partition inside the Boot2Docker virtual machine. Then restart the
daemon.
The following example will enable core dumps inside containers, but you can specify any other options you may need.
boot2docker ssh -t sudo vi /var/lib/boot2docker/profile
# Add something like:
# EXTRA_ARGS="--default-ulimit core=-1"
boot2docker restart
By default, boot2docker
runs docker
with TLS enabled. It auto-generates
certificates and stores them in /home/docker/.docker
inside the VM. The
boot2docker up
command will copy them to ~/.boot2docker/certs
on the
host machine once the VM has started, and output the correct values for
the DOCKER_CERT_PATH
and DOCKER_TLS_VERIFY
environment variables.
eval "$(boot2docker shellinit)"
will also set them correctly.
We strongly recommend against running Boot2Docker with an unencrypted Docker
socket for security reasons, but if you have tools that cannot be easily
switched, you can disable it by adding DOCKER_TLS=no
to your
/var/lib/boot2docker/profile
file.
Boot2Docker is essentially a remote Docker engine with a read only filesystem (other than Docker images, containers and volumes). The most scalable and portable way to share disk space between your local desktop and a Docker container is by creating a volume container and then sharing that to where it's needed.
One well tested approach is to use a file sharing container like
svendowideit/samba
:
$ # Make a volume container (only need to do this once)
$ docker run -v /data --name my-data busybox true
$ # Share it using Samba (Windows file sharing)
$ docker run --rm -v /usr/local/bin/docker:/docker -v /var/run/docker.sock:/docker.sock svendowideit/samba my-data
$ # then find out the IP address of your Boot2Docker host
$ boot2docker ip
192.168.59.103
Connect to the shared folder using Finder (OS X):
Connect to cifs://192.168.59.103/data
Once mounted, will appear as /Volumes/data
Or on Windows, use Explorer to Connect to:
\\192.168.59.103\data
You can then use your data container from any container you like:
$ docker run -it --volumes-from my-data ubuntu
You will find the "data" volume mounted as "/data" in that container. Note that "my-data" is the name of volume container, this is shared via the "network" by the "samba" container that refers to it by name. So, in this example, if you were on OS-X you now have /Volumes/data and /data in container being shared. You can change the paths as needed.
Alternatively, Boot2Docker includes the VirtualBox Guest Additions built in for the express purpose of using VirtualBox folder sharing.
The first of the following share names that exists (if any) will be automatically mounted at the location specified:
Users
share at/Users
/Users
share at/Users
c/Users
share at/c/Users
/c/Users
share at/c/Users
c:/Users
share at/c/Users
If some other path or share is desired, it can be mounted at run time by doing something like:
$ mount -t vboxsf -o uid=1000,gid=50 your-other-share-name /some/mount/location
It is also important to note that in the future, the plan is to have any share
which is created in VirtualBox with the "automount" flag turned on be mounted
during boot at the directory of the share name (ie, a share named home/jsmith
would be automounted at /home/jsmith
).
In case it isn't already clear, the Linux host support here is currently hazy.
You can share your /home
or /home/jsmith
directory as Users
or one of the
other supported automount locations listed above, but note that you will then
need to manually convert your docker run -v /home/...:...
bind-mount host
paths accordingly (ie, docker run -v /Users/...:...
). As noted in the
previous paragraph however, this is likely to change in the future as soon as a
more suitable/scalable solution is found and implemented.
You can add your Registry server's public certificate (in .pem
format) into
the /var/lib/boot2docker/certs/
directory, and Boot2Docker will automatically
load it from the persistence partition at boot.
You may need to add several certificates (as separate .pem
files) to this
directory, depending on the CA signing chain used for your certificate.
As of Docker version 1.3.1, if your registry doesn't support HTTPS, you must add it as an insecure registry.
$ boot2docker init
$ boot2docker up
$ boot2docker ssh "echo $'EXTRA_ARGS=\"--insecure-registry <YOUR INSECURE HOST>\"' | sudo tee -a /var/lib/boot2docker/profile && sudo /etc/init.d/docker restart"
then you should be able to do a docker push/pull.
So sometimes if you are behind a VPN, you'll get an i/o timeout
error.
The current work around is to forward the port in the boot2docker-vm.
If you get an error like the following:
Sending build context to Docker daemon
2014/11/19 13:53:33 Post https://192.168.59.103:2376/v1.15/build?rm=1&t=your-tag: dial tcp 192.168.59.103:2376: i/o timeout
That means you have to forward port 2376
, which can be done like so:
- Open VirtualBox
- Open Settings > Network for your 'boot2docker-vm'
- Select the adapter that is 'Attached To': 'NAT' and click 'Port Forwarding'.
- Add a new rule:
- Protocol: TCP
- Host IP: 127.0.0.1
- Host Port: 5555
- Guest Port: 2376
- Set
DOCKER_HOST
to 'tcp://127.0.0.1:5555'
The boot2docker
management tool allows you to customise many options from both
the command line, or by setting them in its configuration file.
See boot2docker config
for more (including the format of the configuration
file).
$ boot2docker ssh
boot2docker
auto logs in using the generated SSH key, but if you want to SSH
into the machine manually (or you're not using a boot2docker
managed VM), the
credentials are:
user: docker
pass: tcuser
Boot2docker uses Tiny Core Linux, which runs from RAM and so does not persist filesystem changes by default.
When you run boot2docker init
, the boot2docker
tool auto-creates a disk that
will be automounted and used to persist your docker data in /var/lib/docker
and /var/lib/boot2docker
. This virtual disk will be removed when you run
boot2docker delete
. It will also persist the SSH keys of the machine.
Changes outside of these directories will be lost after powering down or
restarting the VM - to make permanent modifications see the
FAQ.
If you are not using the boot2docker
management tool, you can create an ext4
or btrfs
formatted partition with the label boot2docker-data
(mkfs.ext4 -L boot2docker-data /dev/sdX5
) to your VM or host, and Boot2Docker will automount
it on /mnt/sdX
and then softlink /mnt/sdX/var/lib/docker
to
/var/lib/docker
.
To 'install' the ISO onto an SD card, USB-Stick or even empty hard disk, you can
use dd if=boot2docker.iso of=/dev/sdX
. This will create the small boot
partition, and install an MBR.
Goto How to build for Documentation on how to build your own Boot2Docker ISOs.
See the workarounds doc for solutions to known issues.
Sometimes OSX will install updates that break VirtualBox and require a restart of the kernel extensions that boot2docker needs in order to run. If you go to boot boot2docker after some updates or a system restart and you get an output such as the following:
$ boot2docker up
error in run: Failed to start machine "boot2docker-vm" (run again with -v for details)
You may need to reload the kernel extensions in order to get your system functioning again.
In this case, try running the following script (supplied with Virtual Box):
$ sudo /Library/Application\ Support/VirtualBox/LaunchDaemons/VirtualBoxStartup.sh restart
You should see output such as:
/Applications/VirtualBox.app/Contents/MacOS/VBoxAutostart => /Applications/VirtualBox.app/Contents/MacOS/VBoxAutostart-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxBalloonCtrl => /Applications/VirtualBox.app/Contents/MacOS/VBoxBalloonCtrl-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxDD2GC.gc => /Applications/VirtualBox.app/Contents/MacOS/VBoxDD2GC.gc-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxDDGC.gc => /Applications/VirtualBox.app/Contents/MacOS/VBoxDDGC.gc-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxExtPackHelperApp => /Applications/VirtualBox.app/Contents/MacOS/VBoxExtPackHelperApp-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxHeadless => /Applications/VirtualBox.app/Contents/MacOS/VBoxHeadless-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxManage => /Applications/VirtualBox.app/Contents/MacOS/VBoxManage-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxNetAdpCtl => /Applications/VirtualBox.app/Contents/MacOS/VBoxNetAdpCtl-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxNetDHCP => /Applications/VirtualBox.app/Contents/MacOS/VBoxNetDHCP-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxNetNAT => /Applications/VirtualBox.app/Contents/MacOS/VBoxNetNAT-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxSVC => /Applications/VirtualBox.app/Contents/MacOS/VBoxSVC-amd64
/Applications/VirtualBox.app/Contents/MacOS/VBoxXPCOMIPCD => /Applications/VirtualBox.app/Contents/MacOS/VBoxXPCOMIPCD-amd64
/Applications/VirtualBox.app/Contents/MacOS/VMMGC.gc => /Applications/VirtualBox.app/Contents/MacOS/VMMGC.gc-amd64
/Applications/VirtualBox.app/Contents/MacOS/VirtualBox => /Applications/VirtualBox.app/Contents/MacOS/VirtualBox-amd64
/Applications/VirtualBox.app/Contents/MacOS/VirtualBoxVM => /Applications/VirtualBox.app/Contents/MacOS/VirtualBoxVM-amd64
/Applications/VirtualBox.app/Contents/MacOS/vboxwebsrv => /Applications/VirtualBox.app/Contents/MacOS/vboxwebsrv-amd64
Loading VBoxDrv.kext
Loading VBoxUSB.kext
Loading VBoxNetFlt.kext
Loading VBoxNetAdp.kext
Now the VM should boot properly.