The System Controller

The System Controller is the central backend that ties together and controls the different components of the base platform, and that provides the REST API that is used by the user to configure and monitor the system.

When each Agile Live component (such as an Ingest or a Production Pipeline) starts up, it connects to and registers with the System Controller. This means the System Controller must run in a network location that is reachable from all other components.

From release 6.0.0 and on, the System Controller is distributed as a debian package, acl-system-controller. To install the System Controller application, do the following:

sudo apt -y install acl-system-controller_<version>_amd64.deb

The System Controller binary will be installed in the directory /opt/agile_live/bin/ and its configuration file will be placed in /etc/opt/agile_live/.

The System Controller is configured either using a settings file or using environment variables, or a combination thereof. The settings file, named acl_sc_settings.json, is searched for in /etc/opt/agile_live and current directory, or the search path can be pointed to using a flag on the command line when starting the application:

./acl-system-controller for default search paths or ./acl-system-controller -settings-path /path/to/directory/where/settings_file/exists

To use environment variables overriding settings from the configuration file, construct the variables from the json objects in the settings file by prepending with ACL_SC and then the json object flattened out with _ as the delimiter, e.g.:

export ACL_SC_LOGGER_LEVEL=debug
export ACL_SC_PROTO=https

Starting with the basic configuration file in the release, edit a few settings inside it (see this guide for help with the security related parameters):

• change the psk parameter to something random of your own
• change the salt to some long string of your own
• set the username and password to protect the REST API
• specify TLS certificate and key files
• set the host and port parameters to where the System Controller shall be reached

Also consider setting the file_name_prefix to set the log file location, otherwise it defaults to /tmp/.

From the installation directory, the System Controller is started with:

./acl-system-controller

If started successfully, it will display a log message showing the server endpoint.

The System Controller comes with built-in Swagger documentation that makes it easy to explore the API in a regular web browser. To access the Swagger REST API documentation hosted by the System Controller, open https://<IP>:<port>/swagger/ in your browser. The Swagger UI can be used to poll or edit the state of the actual system by using the “Try it out” buttons.

Running the System Controller as a service

It may be useful to run the System Controller as a service in Ubuntu, so that it starts automatically on boot and restarts if it terminates abnormally. In Ubuntu 22.04 systemd manages the services. Here follows an example of how a service can be configured, started and monitored.

First create a “service unit file”, named for example /etc/systemd/system/acl-system-controller.service and put the following in it:

[Unit]
Description=Agile Live System Controller service

[Service]
User=<YOUR_USER>
Environment=<ANY_ENV_VARS_HERE>
ExecStart=/opt/agile_live/bin/acl-system-controller
Restart=always

[Install]
WantedBy=multi-user.target

Replace <YOUR_USER> with the user that will be executing the System Controller binary on the host machine. The Environment attribute is used if you want to set any parameters as environment variables.

After saving the service unit file, run:

sudo systemctl daemon-reload
sudo systemctl enable acl-system-controller.service
sudo systemctl start acl-system-controller

The service should now be started. The status of the service can be queried using:

sudo systemctl status acl-system-controller.service