iframe-proxy

bekiralti · 2026-01-02T18:11:23Z

Integrates the existing load_config method from the villas-node
library into VILLASnodeManager to enable configuration loading
via RabbitMQ messages.

Example

Example (tx.py) Python Code to send messages to villas-controller via RabbitMQ:

import argparse
import json
import kombu

# CLI
parser = argparse.ArgumentParser()
parser.add_argument("action", type=str)
parser.add_argument("config", type=str, nargs="?", default=None)
args = parser.parse_args()

# Broker connection
connection = kombu.Connection("amqp://guest:guest@localhost/%2F")
exchange = kombu.Exchange(name="villas", type="headers", durable=True)
producer = connection.Producer()

# Message
payload = {"action": args.action}
if args.config:
    with open(args.config, "r", encoding="utf-8") as f:
        config = json.load(f)
    payload["config"] = config
producer.publish(payload, exchange=exchange, headers={"type": "villas-node"})

Minimal (example_ctl.json) configuration for villas-controller:

{
  "broker": {
    "url": "amqp://guest:guest@localhost/%2F"
  },
  "components": [
    {
      "category": "manager",
      "type": "villas-node"
    }
  ]
}

Minimal (example_node.json) configuration to sent via RabbitMQ to villas-controller, then villas-controller reloads the running villas-node with this configuration.

{
  "nodes": {
    "my_sig": {
      "type": "signal.v2",
      "rate": 1,
      "in": {
        "signals": [
          {
            "signal": "constant",
            "amplitude": 1
          }
        ]
      }
    }
  },
  "paths": [
    {
      "in": "my_sig",
      "hooks": [
        {
          "type": "print"
        }
      ]
    }
  ]
}

Start RabbitMQ: docker run -p 5672:5672 -p 15672:15672 -d rabbitmq:management
Start villas-node: villas-node
Start villas-controller: villas-controller -c example_ctl.json -d DEBUG daemon
Send example_node.json: python tx.py load_config example_node.json

Signed-off-by: Bekir Altindal <bekir.altindal@rwth-aachen.de>

stv0g · 2026-01-05T08:53:12Z

bekiralti · 2026-01-05T10:48:33Z

Hi @stv0g,

thanks for your reply! Yeah, that is quite troublesome. For now, I would like to try and clarify my intentions and thought process.

While experimenting with VILLASnodeManager, a few questions and observations came up:

In VILLASnodeManager.__init__, there is a line like self._status = self.node.status. This sends a request to the VILLASnode HTTP API and therefore assumes that a villas node process is already running and listening on a port (for example http://localhost:8080). If no process is running, this call results in an urllib.error.URLError in VILLAScontroller.
In order to avoid the above error, a villas node process can be started manually before villas controller, but I have not found a way to let VILLAScontroller reconfigure this manually started villas node process.
The villas-node Python module exposes a load_config method, which can be used to restart a running villas node instance with a new configuration, but it does not seem to be used at the moment, neither in the villas-node Python module itself nor in the VILLAScontroller code.
My intention with the PR was to reuse this existing load_config mechanism in order to reconfigure an already running villas node instance.

To better understand the current behavior, I tried the following:

Start villas node manually without a config.
Start villas controller with a configuration that creates a VILLASnodeManager component and passes a config_filename to the corresponding Node object.
Send {"action": "start"} to this VILLASnodeManager. This successfully starts a second villas node process that uses the configuration specified via config_filename.
This works, but the first, manually started villas node process stays running and unused.

This left me a bit unsure what the intended model for VILLAScontroller is in the case of VILLASnode:

Is VILLAScontroller supposed to manage an already running villas node instance or
is VILLAScontroller supposed to spawn new villas node instances with corresponding configurations?

It is quite possible that I am missing something obvious, and a short clarification would help me to better align future PRs with the intended behaviour. :)

feat: integrate load_config method for VILLASnodeManager

d841971

Signed-off-by: Bekir Altindal <bekir.altindal@rwth-aachen.de>

Sunbelt Computer Software

PL/B Language Development and Support

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feat: integrate load_config method for VILLASnodeManager - #75

feat: integrate load_config method for VILLASnodeManager#75
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bekiralti commented Jan 2, 2026

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bekiralti commented Jan 2, 2026

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