Gazebo is a great tool for simulating robots, but if you want to configure a Gazebo bridge to get simulated data out, you will need to dive into its command line toolset.

Here are 3 quick commands to help with it:

List Gazebo topics:

ign topic -l

Echo a topic:

ign topic -t <topic_name> -e

Get info (data type) about a topic:

ign topic -t <topic_name> -i