Access the OpenStack-API with the CLI-Client
First install the OpenStack-CLI clients with:
pip3 install python-openstackclient python-barbicanclient python-cinderclient python-designateclient python-glanceclient python-heatclient python-neutronclient python-novaclient python-octaviaclient python-magnumclient python-heatclient gnocchiclient
Then you need to download the OpenStack-RC-file in the Horizon webinterface. Click on the "OpenStack RC File" button in the drop down menu in the top-right corner to download the RC File.
Now you can source the RC File. After entering the password you can send requests to the OpenStack-API.
$ source 4894-openstack-c89d2-openrc.sh
Please enter your OpenStack Password for project 4894-openstack-c89d2 as user 4894-openstack-c89d2:
$
$ openstack server list
Have a look at the Cheat-Sheet to find commonly used CLI commands.