echo

README

yggdrasil "echo" worker

This "echo" worker is a simple yggdrasil worker that echoes back the data it is given. It's main function is to provide an example and reference implementation for how a worker could be developed.

Running

The worker can run directly without needing to install it first (go run .). By default, the worker will attempt to connect to an appropriate D-Bus (session or system), depending on whether DBUS_SESSION_BUS_ADDRESS is defined.

D-Bus Service Activation

The worker can be started automatically by the broker. Install the included file com.redhat.Yggdrasil1.Worker1.echo.service into /usr/share/dbus-1/system-services. When the broker receives a message for the address specified by the Name= directive, the worker will be started before the message is delivered.

Should your worker require more advanced start up functionality, it is possible to specify a value for the SystemdService= directive. With such a directive in the service activation file, the D-Bus broker will ask systemd to start the named service. Within that system service file, you can define any resource limitations or environment variables needed for your worker. For example:

[Unit]
Description=yggdrasil echo worker

[Service]
Type=dbus
BusName=com.redhat.Yggdrasil1.Worker1.echo
ExecStart=/usr/libexec/yggdrasil/echo

Note: There is no [Install] section; this is because the service is D-Bus activatable.

See the systemd service examples for detail.