Monthly Archive for July, 2014

Creating Your Own Minimal Docker Image in Fedora

Sometimes it can be useful to have a docker image with just the bare essentials. Maybe you want to have a container with just enough to run your app or you are using something like data volume containers and want just enough to browse the filesystem. Either way you can create your own minimalist busybox image on Fedora with a pretty simple script.

The script below was inspired a little from Marek Goldmann's post about creating a minimal image for wildfly and a little from the busybox website .

# cd to a temporary directory tmpdir=$(mktemp -d) pushd $tmpdir # Get and extract busybox yumdownloader busybox rpm2cpio busybox*rpm | cpio -imd rm -f busybox*rpm # Create symbolic links back to busybox for i in $(./sbin/busybox --list);do ln -s /sbin/busybox ./sbin/$i done # Create container tar -c . | docker import - mybusybox # Go back to old pwd popd

After running the script there is a new image on your system with the mybusybox tag. You can run it and take a look around like so:
[root@localhost ~]# docker images mybusybox REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE mybusybox latest f526db9e0d80 12 minutes ago 1.309 MB [root@localhost ~]# [root@localhost ~]# docker run -i -t mybusybox /sbin/busybox sh # ls -l /sbin/ls lrwxrwxrwx 1 0 0 13 Jul 8 02:15 /sbin/ls -> /sbin/busybox # # ls / dev etc proc sbin sys usr # # df -kh . Filesystem Size Used Available Use% Mounted on /dev/mapper/docker-253:0-394094-addac9507205082fbd49c8f45bbd0316fd6b3efbb373bb1d717a3ccf44b8a97e 9.7G 23.8M 9.2G 0% /