Add Action CLI

[jacobperron]

Created a new package, ros2action, defining the command action. This PR adds implementation for the following verbs:

  info       Print information about an action
  list       Output a list of action names
  send_goal  Send an action goal
  show       Output the action definition

Connects to #202
Requires ros2/rcl#411
Requires ros2/rclpy#306

[jacobperron]

I still need to add auto-completion and do more testing.

Running CI to find any issues early:

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[Karsten1987]

Not sure how trivial it is, but somehow echoing the feedback after submitting a goal would be extremely handy I believe.
Maybe the sending the goal can return an ID which can then be used to reference the feedback or so.

[jacobperron]

Currently, the send_goal verb is blocking until the goal completes and echos the sent goal, result, and optional feedback. For example:

$ ros2 action send_goal --feedback /fibonacci example_interfaces/Fibonacci "order: 5"
Waiting for an action server to become available...
Sending goal:
     order: 5

Feedback:
    sequence: [0, 1, 1]

Feedback:
    sequence: [0, 1, 1, 2]

Feedback:
    sequence: [0, 1, 1, 2, 3]

Feedback:
    sequence: [0, 1, 1, 2, 3, 5]

Result:
    sequence: [0, 1, 1, 2, 3, 5]

Goal finished with status: SUCCEEDED

I agree that also echoing the goal ID would be useful.

[jacobperron]

This should be ready for review.

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[Karsten1987]

The command line tool looks great to me. I can send a command, get the feedback and see the action definitions. 👍

Only nitpick I had was for the ros2 action info command. I can't really figure out why we would need to have -c as an option. The other thing is that ros2 action info <topic> is different from ros2 action /<topic>. I believe as with other ros2cli tools, the forward slash should be added automatically if suited.

[Karsten1987]

I'll give you a 👍 , but you might want to have somebody look over the code who has a more critical eye on Python code than me :)

[jacobperron]

The other thing is that ros2 action info is different from ros2 action /. I believe as with other ros2cli tools, the forward slash should be added automatically if suited.

I was trying to mimic ros2 topic info, which also has a -c option. I'll look into adding the forward slash.

[jacobperron]

@Karsten1987

ros2 action info is different from ros2 action /. I believe as with other ros2cli tools, the forward slash should be added automatically if suited.

I think I've addressed this in 0d13d00.

Also, now printing the goal UUID in hex format (8ef62e0)

[Karsten1987]

The forward slash situation was addressed. 👍

I have two more remarks though:

• ros2 action show: Would be great to have a -t, --types option just like ros2 topic list to have an idea of the actions and their types. That also makes calling ros2 action show easier.
• ros2 action send_cancel: Now that send_goal returns a ID for the action, do you think it's feasible to add a cancel command which takes this ID and thus sends out a cancel request. I think that could be helpful.

[jacobperron]

Thanks @Karsten1987!

ros2 action show: Would be great to have a -t, --types option just like ros2 topic list to have an idea of the actions and their types. That also makes calling ros2 action show easier.

I plan to make this feature as part of a new interface command as described in #202 (comment). Expect a follow up PR with this.

ros2 action send_cancel: Now that send_goal returns a ID for the action, do you think it's feasible to add a cancel command which takes this ID and thus sends out a cancel request. I think that could be helpful.

This reminded me that the intention was to cancel the goal if the user terminates the send_goal command before an action completes (I'll look into adding that to this PR).

I can also see the value in a separate cancel verb for interacting with a goal not started by the CLI tool, but I think we can save it for a follow-up ticket. Maybe good to discuss as part of #202.

I've updated the send goal logic to account for a SIGINT or errors.

[sloretz]

LGTM with nitpicks fixed and green CI. It works fine, including tab completion, on my machine.

[jacobperron]

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[jacobperron]

I would rather only catch expected exceptions here - basically the two handle before within the function. That way in case of an unexpected exception you still get a valuable stackable.

Done 6a62cb8

[jacobperron]

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