As found on the Odoo.sh FAQ:
Python dependencies:
You can define requirements.txt files in your branch holding the python dependencies your project relies on. These requirements files can be placed in the root of the folders containing your addons. The platform will then install the dependencies for each build.
System dependencies:
This is currently not possible to install system packages (e.g. apt packages).
Nevertheless, if the package could be useful for more than one project, we will consider to install it by default in the containers images if the package meets the following requirements:
- there should be not conflict with the rest of the packages
- the software should not run as a long running service or daemon
- no elevated privileges or additional system user should be required
- the software should not directly or indirectly represent a security attack vector
- the software should run flawlessly in a constrained linux namespace environment with cgroup limits on memory, processes, threads, files, ... (this excludes greedy VMs such as java)
Same goes for python modules requiring system packages for their compilation. In such a case, leave us a feedback and provide us with some details about your use-case.
PostgreSQL dependencies:
PostgreSQL extensions are not supported on Odoo.sh hence it is not possible to install extensions (such as PostGIS, ltree, ...) in an Odoo.sh database.