Sackman shrinks containers by throwing out unused files.
The C code is based on Remi Flament's LoggedFS (https://github.com/rflament/loggedfs).
Call sackman like you would call podman run:
$ DST_IMAGE=test sackman run docker.io/library/ubuntu:14.04 cat /etc/lsb-release
NOTE: For options that appear prior to the image name:
Do not put a space in front of option-values. Use --option-name=VALUE or -oVALUE instead.
Otherwise sackman may not identify the image name correctly.
While the container is running sackman will record all accessed file paths. Finally a squashed copy of the origial image will be created containing only the accessed files.
You can configure sackman with the following environment variables:
DST_IMAGE - The name of the final image.
FILE_LOG - Accessed paths are written to this file.
RSYNC_FILES - A path to a file containing additional files to copy.
RSYNC_OPTS - Can be set to "-v" to output all copied files.
$ make
$ sudo make install
or
$ PREFIX=$HOME/.local make -e install
Sackman has the following dependencies:
podman
buildah
fuse
rsync
You also need the usual build tools to compile sackman.
Install fuse on Fedora with:
dnf install fuse-devel
Install fuse on Depian/Ubuntu with:
apt install libfuse-dev