Bus.yml doesn't compile if the "nodes" section is missing?

[BatisteAll]

Describe the bug
It seems, in my current set up, that the bus.yml won't compile if I simply list the slave robot joints (so without a nodes section) as follow:

options:
  dcf_path: "@BUS_CONFIG_PATH@"

master:
  node_id: 1
  driver: "ros2_canopen::MasterDriver"
  package: "canopen_master_driver"
  sync_period: 10000

joint_1:
  node_id: 2
  dcf: "cia402_slave.eds"
  driver: "ros2_canopen::Cia402Driver"
  package: "canopen_402_driver"
  period: 10
  position_mode: 1
  revision_number: 0
  sdo:
    - {index: 0x60C2, sub_index: 1, value: 50} # Set interpolation time for cyclic modes to 50 ms
    - {index: 0x60C2, sub_index: 2, value: -3} # Set base 10-3s
    - {index: 0x6081, sub_index: 0, value: 1000}
    - {index: 0x6083, sub_index: 0, value: 2000}
    - {index: 0x6060, sub_index: 0, value: 7}
  tpdo: # TPDO needed statusword, actual velocity, actual position, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6041, sub_index: 0} # status word
        - {index: 0x6061, sub_index: 0} # mode of operation display
    2:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6064, sub_index: 0} # position actual value
        - {index: 0x606c, sub_index: 0} # velocity actual position
  rpdo: # RPDO needed controlword, target position, target velocity, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x6040, sub_index: 0} # controlword
      - {index: 0x6060, sub_index: 0} # mode of operation
    2:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x607A, sub_index: 0} # target position
      #- {index: 0x60FF, sub_index: 0} # target velocity

joint_2:
  node_id: 3
  dcf: "cia402_slave.eds"
  driver: "ros2_canopen::Cia402Driver"
  package: "canopen_402_driver"
  period: 10
  position_mode: 1
  revision_number: 0
  switching_state: 2
  sdo:
    - {index: 0x60C2, sub_index: 1, value: 50} # Set interpolation time for cyclic modes to 50 ms
    - {index: 0x60C2, sub_index: 2, value: -3} # Set base 10-3s
    - {index: 0x6081, sub_index: 0, value: 1000}
    - {index: 0x6083, sub_index: 0, value: 2000}
    - {index: 0x6060, sub_index: 0, value: 7}
  tpdo: # TPDO needed statusword, actual velocity, actual position, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6041, sub_index: 0} # status word
        - {index: 0x6061, sub_index: 0} # mode of operation display
    2:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6064, sub_index: 0} # position actual value
        - {index: 0x606c, sub_index: 0} # velocity actual position
  rpdo: # RPDO needed controlword, target position, target velocity, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x6040, sub_index: 0} # controlword
      - {index: 0x6060, sub_index: 0} # mode of operation
    2:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x607A, sub_index: 0} # target position
      #- {index: 0x60FF, sub_index: 0} # target velocity

But if I add an indentation level on the joints and add the 'nodes' section, in that case it compiles:

options:
  dcf_path: "@BUS_CONFIG_PATH@"

master:
  node_id: 1
  driver: "ros2_canopen::MasterDriver"
  package: "canopen_master_driver"
  sync_period: 10000

nodes:
  joint_1:
     ...
  joint_2:
     ...

Logs
The only log is when I colcon build my config package, the bus.yml doesn't get parsed and the 'preprocessed_bus.yml' is not created.
So I get an error of type:

sed: can't read /home/ros2_ws_canopen/build/lab_canopen_config/config/bus/preprocessed_bus.yml: No such file or directory
gmake[2]: *** [CMakeFiles/bus.dir/build.make:74: bus] Error 2
gmake[1]: *** [CMakeFiles/Makefile2:165: CMakeFiles/bus.dir/all] Error 2
gmake: *** [Makefile:146: all] Error 2

Setup:

• OS: Ubuntu 22.04
• ROS-Distro: Humble
• Branch/Commit: Humble

Additional context
I am using ros2_canopen with ros2_control.
The bus.yml I used is as presented above, a copy of the bus.yml in ros2_canopen>canopen_tests>config>robot_control.

[danzimmerman]

If you really want to do this you could modify cogen.py here to handle the case where you don't specify the nodes section, but I just think that's what's expected of the interface at this time.

You can use defaults to specify all the common stuff between the two and just have a short nodes section that names them and captures their differences:

defaults:
  dcf: "cia402_slave.eds"
  driver: "ros2_canopen::Cia402Driver"
  package: "canopen_402_driver"
  period: 10
  position_mode: 1
  revision_number: 0
  sdo:
    - {index: 0x60C2, sub_index: 1, value: 50} # Set interpolation time for cyclic modes to 50 ms
    - {index: 0x60C2, sub_index: 2, value: -3} # Set base 10-3s
    - {index: 0x6081, sub_index: 0, value: 1000}
    - {index: 0x6083, sub_index: 0, value: 2000}
    - {index: 0x6060, sub_index: 0, value: 7}
  tpdo: # TPDO needed statusword, actual velocity, actual position, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6041, sub_index: 0} # status word
        - {index: 0x6061, sub_index: 0} # mode of operation display
    2:
      enabled: true
      cob_id: "auto"
      transmission: 0x01
      mapping:
        - {index: 0x6064, sub_index: 0} # position actual value
        - {index: 0x606c, sub_index: 0} # velocity actual position
  rpdo: # RPDO needed controlword, target position, target velocity, mode of operation
    1:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x6040, sub_index: 0} # controlword
      - {index: 0x6060, sub_index: 0} # mode of operation
    2:
      enabled: true
      cob_id: "auto"
      mapping:
      - {index: 0x607A, sub_index: 0} # target position
      #- {index: 0x60FF, sub_index: 0} # target velocity

nodes:
  joint_1:
    node_id: 2
  joint_2:
    node_id: 3
    switching_state: 2

The bus.yml I used is as presented above, a copy of the bus.yml in ros2_canopen>canopen_tests>config>robot_control.

I think that's the equivalent of a preprocessed_bus.yml file. You should be able to run dcfgen on it directly, like the CMake macro cogen_dcf() does here: https://github.com/ros-industrial/ros2_canopen/blob/master/lely_core_libraries/cmake/lely_core_libraries-extras.cmake#L53

But if you want to use bus.yml it does expect the nodes entry, like here:

https://ros-industrial.github.io/ros2_canopen/manual/rolling/user-guide/configuration.html#bus-configuration-file