congress-server software package provides OpenStack Policy as a Service - API server, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install congress-server
congress-server is installed in your system.
Make ensure the congress-server package were installed using the commands given below,
$ sudo dpkg-query -l | grep congress-server *
You will get with congress-server package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Network |
| Package | congress-server |
| Version | 4.0.0+dfsg1-3 |
| Description | OpenStack Policy as a Service - API server |
| Sub Section | Net |