DevOps Dojo: CI - JSON Schema Validation of YAML Parameter File(s)

[kaspermeck-arm]

Checklist

• I've read the contribution guidelines.
• I've searched other issues and no duplicate issues were found.
• I've agreed with the maintainers that I can plan this task.

Description

JSON Schema validation to ensure that parameter file(s) are valid.

Purpose

Ensure that parameter files are valid to mitigate misconfiguration of ROS nodes.

Possible approaches

E.g., https://github.com/marketplace/actions/frontmatter-json-schema-validator

Definition of done

Pass/Fail for the JSON Schema validation using draft-07.
Pass/Fail for /<path_to_package>/schema/*.schema.json validation of parameter file(s) in /<path_to_package>/config/*.param.json.

[kaspermeck-arm]

@xmfcx @mitsudome-r

I spoke to @ambroise-arm earlier today. Arm is willing to take this issue on and with your input and feedback, add the validation into GitHub Actions.

[xmfcx]

json-yaml-validate might be a better option since frontmatter-json-schema-validator is for YAML front matter. Maybe we can also use the same action to validate the JSON files too.

[ambroise-arm]

autowarefoundation/autoware.universe#4002 is a PR for validating the JSON Schema files against their meta-schema. This is the first half of the work. The other half is validating the yaml configuration files against the schema files, I still need to look at that.

EDIT: I am not using the suggested json-yaml-validate for that because it is designed to take in a single schema to validate multiple files against. Whereas our usecase is to have multiple pairs of yaml/json where we want to validate each yaml config file against its associated json schema.

[kaspermeck-arm]

autowarefoundation/autoware.universe#4002 is a PR for validating the JSON Schema files against their meta-schema. This is the first half of the work. The other half is validating the yaml configuration files against the schema files, I still need to look at that.

EDIT: I am not using the suggested json-yaml-validate for that because it is designed to take in a single schema to validate multiple files against. Whereas our usecase is to have multiple pairs of yaml/json where we want to validate each yaml config file against its associated json schema.

@ambroise-arm thanks for taking this on!

There might be cases where the are more than one *.param.yaml files in the config/ directory.

[kaspermeck-arm]

The GitHub action which validates the parameter file using the schema is now merged!
autowarefoundation/autoware.universe#4122

[kaspermeck-arm]

Find the GitHub action running here: https://github.com/autowarefoundation/autoware.universe/actions/workflows/json-schema-check.yaml

[kaspermeck-arm]

@KYabuuchi thanks for your comment and helping us create a more rigid way with the parameters aspect of Autoware.

I'm not quite following your thought process and I don't understand where the complication is. I've tried to describe the process in a few bullet points:

• A ROS package can have none or many nodes
• Each node has one schema associated with it
• A node has one or more parameter files associated with it
• The schema validates the parameter file(s)

Am I addressing the issue with these bullet points?

We have not yet started the DevOps Dojo: ROS Node Launch. I do believe that overwriting parameters can be useful but also has risks, as you also mention. As soon as a parameter is configured outside of the parameter file, it cannot be validated by the schema, or at least not with how we validate parameter files today.

@ambroise-arm

[KYabuuchi]

@kaspermeck-arm Thank you for describing.

I noticed that a PR has been developed to address case 3 of my concerns. This will eventually be resolved. 👍

However, the bullet points do not consider nodes that load multiple parameter files. Some nodes store their parameters in separate files and load multiple parameter files during launch.

For example, probabilistic_occupancy_grid_map loads two files.

Additionally, parameter overrides within launch files might lead to misunderstandings and bugs. Nevertheless, removing parameters determined at startup is challenging, so it would be helpful to have a method for handling this on the validation side.

[kaspermeck-arm]

@KYabuuchi

Just to understand.

1. Why is it desirable to provide multiple parameter files to launch a single node?
2. When would you want to determine parameters at startup?

[KYabuuchi]

@kaspermeck-arm

1. Why is it desirable to provide multiple parameter files to launch a single node?

In cases where developers want to prepare presets corresponding to several modes, they create multiple parameter files.
For example, the probabilistic_occupancy_grid_map has parameter files that vary based on observation methods and another set of parameter files for independent update rules.
If all parameters are stored in a single file, the number of files becomes large and difficult to maintain when there are many preset combinations.

Moreover, when some parameters are shared with other nodes, multiple parameter files may also be passed to a node.
For example, both the lane_departure_checker and vehicle_cmd_gate nodes require parameters such as the vehicle's wheel_base and max_steer_angle. These parameters are stored in the vehicle_info.param.yaml file.
These nodes, in order to read both the vehicle-related parameters and their specific parameters, load multiple parameter files.

2. When would you want to determine parameters at startup?

The paths for maps and DNN models and the localization mode are provided by the user during startup.
These parameters need to be provided not only to a single node but also to several nodes. Therefore, they are not managed in parameter files but are passed to the nodes from the launch file using <param name= instead of <param from=config.yaml.

[kaspermeck-arm]

@KYabuuchi

1. Thanks, that makes sense. Removing the parameters from being required is one way to resolve this. @ambroise-arm - what do you think?
2. Would it be possible to set this to an environment variable?
   Schema:

        "test_env_var": {
          "type": "string",
          "description": "Environment variable",
          "default": "${ENV_VAR}",
          "enum": ["${ENV_VAR}"]
        }

and parameter file

    test_env_var: ${ENV_VAR}

[ambroise-arm]

Removing the parameters from being required is one way to resolve this. @ambroise-arm - what do you think?

Yes, It is one way to resolve this.

But I think the launch_ros rules in https://github.com/ros2/launch_ros/blob/humble/launch_ros/launch_ros/actions/node.py#L175-L182 are not that complex. And they would allow to keep all schema fields as required, even if some of the parameter from the config file are meant to always be overridden. In order to avoid bugs, I think the only thing we need to ensure is that the default parameter file of a package uses a "/**" namespace, which should already be enforced in the schema files (for example: https://github.com/autowarefoundation/autoware.universe/blob/main/perception/lidar_apollo_segmentation_tvm_nodes/schema/lidar_apollo_segmentation_tvm_nodes.schema.json#L87). It may indeed hurt clarity, as changing some of the values of the package's parameter file will have an effect, but not for others. But I think it is already not clear where parameters are set and how they are propagated in launch files, so it seems like a minor issue to me.

Also about validating multiple parameter files, I think the goal was never to validate the parameter files held by the launch packages. So I don't think multiple parameter file is an issue beyond validating those default parameters files. Please someone correct me if my assumption is incorrect.

And keeping all fields required seems especially important if we intend to rework the launch files in the future, as it keeps things clean and consistent.

(but also I am not in charge of maintaining the launch and parameter files working well together, and I understand the reluctance to change what currently works)

Would it be possible to set this to an environment variable?

It might, but I don't think we want to introduce another way to set parameters.

[KYabuuchi]

@ambroise-arm @kaspermeck-arm

Would it be possible to set this to an environment variable?
test_env_var: ${ENV_VAR}

Sorry, is this method actually valid for ros2 node? I have never seen this approach, and when I tried it, the variables were passed as strings without being interpreted.
If we want to reference environment variables during the startup, it is more common to use the $(env ) command within the launch file. And I do not think this would work in a parameter file.

Even if it is a valid method, I also do not think we want to introduce a new way to set parameters.

[kaspermeck-arm]

@ambroise-arm @KYabuuchi

I suggest the following:

1. Let's keep the the required fields in the schema and it will validate a default parameter file. For testing purposes, having a single complete parameter file is important. Then allow for parameters to be overwritten in the launch file. Does this sound OK?

2. Ok, let's pass on my ${ENV_VAR} idea. For variables which use environmental variables, let's rely on the $(env ) command. E.g.,

Schema:

        "data_path": {
          "type": "string",
          "description": "Absolute path to data and artifacts packages directory.",
          "default": "abs_path_to_data_and_artifacts"
        }

and parameter file:

/**:
  ros__parameters:
    data_path: abs_path_to_data_and_artifacts

Which will be overwritten using:

<arg name="data_path" default="$(env HOME)/autoware_data">

Does this sound OK?

[ambroise-arm]

is this method actually valid for ros2 node?

@KYabuuchi Yes, you just need to allow the launch file to interpret it correctly. See yolo_v2_tiny_example.param.yaml and allow_substs="true" in yolo_v2_tiny_example.launch.xml

Ok, let's pass on my ${ENV_VAR} idea. For variables which use environmental variables, let's rely on the $(env ) command.

@kaspermeck-arm I think the point of @KYabuuchi was that those $... were meant to be used in the launch file, as opposed to the parameter file. Not ${...} vs $(env ...).

For the data path of the artifacts, I think the yolo_v2_tiny links above are also a very good example of what can be done then.

But then I think there is a distinction between using $HOME or $(find-pkg-share ...) in a parameter file (which don't require the user to do anything and I think are quite useful to have in parameter files), and creating custom new environment variables (which is what I thought we were talking about above and I am against doing)

[kaspermeck-arm]

@KYabuuchi - I aligned with @ambroise-arm and this is our proposal.

All parameters which are expected to be used in a node must exist in the schema and parameter file according to the contribution guide. This is necessary for rendering the table view in the documentation and for testing purposes. There is nothing preventing multiple parameter files in the launch file.

The yolov2 tiny example resolves the environmental parameter issue. In the schema

• yolo_v2_tiny_example.schema.json

the env command is used:

        "data_path": {
          "type": "string",
          "default": "$(env HOME)/autoware_data",
          "description": "Packages data and artifacts directory path."
        }

And the corresponding parameter file

• yolo_v2_tiny_example.param.yaml

/**:
  ros__parameters:
    ...
    data_path: $(env HOME)/autoware_data

Finally, in the launch file

• yolo_v2_tiny_example.launch.xml

the following line needs to be added:

<param from="$(var tvm_utility_example_node_param_path)" allow_substs="true"/>

Note allow_substs="true", which enables the commands from the parameter file to be resolved.

Does this solve the problems which you're facing?

[KYabuuchi]

@kaspermeck-arm Thank you for explaining the method using environment variables. But, it is difficult for me to judge whether that method is appropriate or not.
If you are going to proceed with using new environment variables, it would be better to summarize the modifications and ask for feedback not only in this thread but also in the discussion space. 🙏

[kaspermeck-arm]

@KYabuuchi - that's a good point that this could be a larger discussion. I'll bring this topic up in the next OADK meeting!

In my opinion there is no technical difference to setting the environmental parameters in the parameter file vs the launch file. It is however more transparent and follows the current contribution implementation details to do this in the parameter file.

[doganulus]

When and who performs the variable substitution here? As late as node initialization or at an earlier step?

[kaspermeck-arm]

@doganulus - my understanding is that it's resolved when running the ros launch command, so during node initialization.

Edit: https://docs.ros.org/en/iron/Releases/Release-Galactic-Geochelone.html#use-launch-substitutions-in-parameter-files

[isamu-takagi]

Launch configuration can also be used. I think this is easier to use because it has a narrower scope than environment variables.

test.param.yaml

/**:
  ros__parameters:
    foo: $(var foo)
    bar: data-bar
    baz: data-baz

test.launch.xml

<group>
  <let name="foo" value="test-foo"/>
  <node pkg="test_pkg" exec="node" name="node">
    <param from="$(find-pkg-share test_pkg)/config/test.param.yaml" allow_substs="true"/>
  </node>
</group>

output

foo: test-foo
bar: data-bar
baz: data-baz

[doganulus]

I am leaning towards that keeping *.param.yml node parameter files free of any variable substitution as this means the implicit use of ros launch, which performs the substitution. If we want to use Eclipse Bluechi or Ankaios at some point, these tools probably would not support variable substitution as ros launch.

So the following solution would be more robust if my last assumption is true.

First, we have a pure yaml parameter file.

# test.param.yml
/**:
  ros__parameters:
    foo: /opt/autoware/<component>/<node>/config/test.param.yaml # Hardcoded conventional path
    bar: data-bar
    baz: data-baz

Then, I assume parameter overwrite will work as follows (needs to be verified):

# test.launch.xml
<group>
  <node pkg="test_pkg" exec="node" name="node">
    <param from="$(find-pkg-share test_pkg)/config/test.param.yaml" allow_substs="true"/>
    <param name="foo" value="test-foo"/>
  </node>
</group>

[kaspermeck-arm]

@doganulus - I'm not following your reasoning regarding Bluechi and Ankaios. These are orchestrators, like k3s. Are you suggesting that these will remove the need to use the ros launch command entirely?

[doganulus]

@kaspermeck-arm Yes, in the long run though. Those projects are at early stages but I think they can start ROS/Zenoh executables or containers directly.

[kaspermeck-arm]

@doganulus - moving away from using ros launch to launch ROS nodes is something which I've never considered and I don't know how that would work in practice. I think this topic in and of itself is a way bigger topic of discussion.

The experience I have with BlueChi is that it is Kubernetes yaml compatible, translates these files to systemd service files and then runs containers as systemd services. When the container is launched, a command/file inside that environment is run (e.g., entry point file) and for ROS that would be the ros launch command. Can you share more information on how these orchestrators will address launching ROS nodes without using the ros launch command?

[doganulus]

I think this topic in and of itself is a way bigger topic of discussion.

Definitely needs a bigger discussion. Below is a starting example.

For the example, let's work in a test container:

docker run --rm -it ros:humble

And we install some example ROS nodes inside the container, create an example param.yml file, and start the ROS node parameter_blackboard directly as follows:

apt update && apt install -y ros-humble-demo-nodes-cpp
printf '/**:\n  ros__parameters:\n    a_string: $(env HOME)/autoware_data\n' >> param.yml
/opt/ros/humble/lib/demo_nodes_cpp/parameter_blackboard --ros-args --params-file param.yml & # Launch the node directly
ros2 param get parameter_blackboard a_string                                                 # Check the parameter set                         

Normally, the command ros launch is a convenient way to start (many) nodes via launch files but we also can start nodes directly as in the example. And here we are able to set parameters using --params-file argument. First observation, starting nodes directly does not substitute variables as you can see in the output. I think it is a feature of ros launch. Therefore, I suggest not using variable or shell commands in the parameter files, which can be used outside ros launch.

Then, if we can start nodes directly in this way, systemd can start them via unit files. And this is the connection with other projects. I think BlueChi can orchestrate all ROS node unit files all at some point.

[kaspermeck-arm]

@doganulus

I understand your point of not being dependent on ros launch and I think this is fair. However, not using variable/shell commands in the parameter files complicate things. This is a very useful feature of ROS as hard-coded environmental variables would be very tedious to change and not flexible, i.e., going against our goal of making Autoware software-defined.

How about we find a way to evaluate these variable/shell commands and then write the output to a new interpreted parameter file which is free of variable/shell commands and with the correct, e.g., paths to local directories. What do you think?

[doganulus]

I am not absolutely against parameter file templates and environment variables in parameter files. They can be very handy when they are used right.

The current implementation does not feel right, as parameter files reside at a lower level than launch descriptions. Hence, parameter files should not be aware of specific ros launch features. If we could bring the substitution functionality to the lower level, then my objection would be resolved.

But this is not an easy task to handle properly. So I do not suggest immediate action as we gonna use ros launch for some time anyway. Still, avoiding variables as much as possible would be better. Setting some path conventions in the OpenAD Kit may help reduce the need for configuration.

[kaspermeck-arm]

@doganulus

In the end, Autoware is a ROS project and I am in favor of using the features which ROS provides to make it more convenient to configure nodes. The situation with adding a schema was different as there was no solution to this built into ROS already. I suggest that if someone has different needs, i.e., no dynamic variables in the parameter file, then they can make these changes themselves with, e.g., a parameter resolving script. If you want to bring this topic further, I suggest you create a new discussion with all the background.

[doganulus]

The clash between ROS practices and modern cloud-native practices is unavoidable. I side with the latter when they overlap.

As a compromise: We can at least restrict it to $VAR or ${VAR} syntax for environment variables. That can be substituted by external tools like envsubst. We don't have this opportunity for $(find-pkg-share) and friends.