server yaml file substitute with temporary files

[knmcguire]

I figured out a solution that kind of works here without much change on the user side. So if the user just does this:

ros2 launch crazyflie launch.py backend:=sim

Nothing changes really, except for there is a tmp file that is made especially for the server

but if the user defines a yaml file with different parameters like here

ros2 launch crazyflie launch.py backend:=sim server_yaml_file:='test.yaml'

then the server is initialized with that yaml file instead, which should include all the parameters necessary for that server.

I don't like that a temporary yaml file needs to be made in order for this to work. On the other hand, it also provides a template which users can use to make an modify their own yaml file.

[knmcguire]

@Khaledwahba1994 or @akmaralAW, since wolfgang will not be available for this, perhaps you can express your opinion of what you think of this strategy?

[akmaralAW]

Hi @knmcguire!

did I understand correctly that this file (server_yaml_file:='test.yaml') is similar to server.yaml, and you want to be able to support easy, user-friendly configuration of some parameters ?

[knmcguire]

well it's actually a bit more complicated, since the launch.py file appends more parameters to the server like the crazyflies and some things for mocap. What I proposed here is that the launch file makes a temporary yaml file with all of those things combined (so the 'true' server yaml file). These are the parameters than can be replaced by the users' choosing.

This was done because it was otherwise difficult to have the script choose between a dictionary (what the serverparams was inputed for the server node)
or the content of a file.

[knmcguire]

mind that this is just a draft still and not fully distributed to all the other .yaml files. Just looking for an opinion here but don't merge it yet obviously :)

[akmaralAW]

To me it makes sense to have this separate, easy-to-change server file (if parameters are specific to use cases and need to be changed frequently). And in case no change is needed, then server_yaml_file:='test.yaml' can be skipped and we still can run the command.

[knmcguire]

I've implemented the same strategy for mocap as well, and the teleop node now receives the teleop.yaml file directly (or an external one). The PR is no longer a draft now.

One comment though on this approach, I'm not sure if the temp yaml file fix will be something that works if we release this as an official ROS binary. Perhaps it might be better to have another node that changes the parameters after the nodes has been initialized, but let's cross that bridge once we get there :)