The Docker builds for this release are available as of yesterday. To install 1.5.7 specifically, run the command:
$ docker pull ledgersmb/ledgersmb:1.5.7
The team is proud to announce a tremendous size optimization of the docker image as of this release: the 1.5.6 release was reported to be "1GB" on Docker Hub, the 1.5.7 size is now only 289MB(!). Similar size savings have been achieved for the installed images: where Docker was reporting 2.2GB "virtual size" for 1.5.6, it is now reporting only 718MB(!) for 1.5.7.
Please note that the LedgerSMB functionality provided by the container has *not* changed; the size reduction has been achieved by reducing the number of dependencies(-of-dependencies) that Debian automatically installs when installing LedgerSMB's dependencies. Also, a different container has been chosen to bootstrap the container from (we have switched from Perl:5 to Debian:Jessie).