Malformed Discovery Message causes c-flo to stop

[uwekamper]

A previous version of cdmmpqtt.py (https://github.com/c-base/cdmmpqtt) did publish a discovery message that did not include the "inports"-list. This caused c-flo to stop working. Here is the error message:

May 14 03:31:26 c-flo node[3134]: Participant discovery failed: Discovery message missing .inports
May 14 03:31:26 c-flo node[3134]:  Error: Discovery message missing .inports
May 14 03:31:26 c-flo node[3134]:     at Coordinator.participantDiscovered (/opt/c-flo/node_modules/msgflo/src/coordinator.coffee:168:11)
May 14 03:31:26 c-flo node[3134]:     at Coordinator.handleFbpMessage (/opt/c-flo/node_modules/msgflo/src/coordinator.coffee:160:8)
May 14 03:31:26 c-flo node[3134]:     at /opt/c-flo/node_modules/msgflo/src/coordinator.coffee:135:14
May 14 03:31:26 c-flo node[3134]:     at MessageBroker.Client._onMessage (/opt/c-flo/node_modules/msgflo-nodejs/lib/mqtt.js:165:22)
May 14 03:31:26 c-flo node[3134]:     at MqttClient.<anonymous> (/opt/c-flo/node_modules/msgflo-nodejs/lib/mqtt.js:58:26)
May 14 03:31:26 c-flo node[3134]:     at emitThree (events.js:116:13)
May 14 03:31:26 c-flo node[3134]:     at MqttClient.emit (events.js:197:7)
May 14 03:31:26 c-flo node[3134]:     at MqttClient._handlePublish (/opt/c-flo/node_modules/mqtt/lib/client.js:816:12)
May 14 03:31:26 c-flo node[3134]:     at MqttClient._handlePacket (/opt/c-flo/node_modules/mqtt/lib/client.js:286:12)
May 14 03:31:26 c-flo node[3134]:     at process (/opt/c-flo/node_modules/mqtt/lib/client.js:242:12)
May 14 03:31:26 c-flo node[3134]:     at Writable.writable._write (/opt/c-flo/node_modules/mqtt/lib/client.js:252:5)
May 14 03:31:26 c-flo node[3134]:     at doWrite (/opt/c-flo/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:338:64)
May 14 03:31:26 c-flo node[3134]:     at writeOrBuffer (/opt/c-flo/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:327:5)
May 14 03:31:26 c-flo node[3134]:     at Writable.write (/opt/c-flo/node_modules/mqtt/node_modules/readable-stream/lib/_stream_writable.js:264:11)
May 14 03:31:26 c-flo node[3134]:     at Socket.ondata (_stream_readable.js:555:20)
May 14 03:31:26 c-flo node[3134]:     at emitOne (events.js:96:13)
May 14 03:31:26 c-flo node[3134]:     at Socket.emit (events.js:191:7)
May 14 03:31:26 c-flo node[3134]:     at readableAddChunk (_stream_readable.js:176:18)
May 14 03:31:26 c-flo node[3134]:     at Socket.Readable.push (_stream_readable.js:134:10)
May 14 03:31:26 c-flo node[3134]:     at TCP.onread (net.js:563:20)
May 14 03:31:26 c-flo node[3134]:
May 14 03:31:26 c-flo node[3134]:  {"command":"participant","protocol":"discovery","payload":{"component":"c-base/music-player","label":"Show URL on a public screen.","outports":[{"queue":"megablast/current_song","type":"object","description":"JSON object of the current song being played.","id":"current_song"}],"role":"megablast","id":"cdmmpqtt83779605327991","icon":"television"}}

Restarting the c-flo.service using systemctl would then result in the following error.

May 14 04:04:22 c-flo node[3854]: --forever enabled
May 14 04:05:03 c-flo node[3854]: /opt/c-flo/node_modules/msgflo/src/msgflo.coffee:31
May 14 04:05:03 c-flo node[3854]:         throw err;
May 14 04:05:03 c-flo node[3854]:         ^
May 14 04:05:03 c-flo node[3854]: Error: Waiting for participant nerdctrl-display timed out
May 14 04:05:03 c-flo node[3854]:     at Timeout._onTimeout (/opt/c-flo/node_modules/msgflo/src/coordinator.coffee:74:21)
May 14 04:05:03 c-flo node[3854]:     at ontimeout (timers.js:380:14)
May 14 04:05:03 c-flo systemd[1]: c-flo.service: Main process exited, code=exited, status=1/FAILURE
May 14 04:05:03 c-flo systemd[1]: c-flo.service: Unit entered failed state.
May 14 04:05:03 c-flo systemd[1]: c-flo.service: Failed with result 'exit-code'.

Stopping c-flo, reverting graphs/c-base.json to the last working version and then restart c-flo resolved the issue.

To reproduce the issue one can create a discovery message like this:

discovery_message = {
        "command": "participant",
        "protocol": "discovery",
        "payload": {
            "component": "c-base/music-player",
            "label": "Show URL on a public screen.",
            # "inports": [], ### inports missing ###
            "outports": [
                {
                    "queue": "%s/current_song" % mqtt_client_name,
                    "type": "object",
                    "description": "JSON object of the current song being played.",
                    "id": "current_song",
                }
            ],
            "role": "%s" % mqtt_client_name,
            "id": mqtt_client_id,
            "icon": "television"
        },
    }

[bergie]

Moved to upstream msgflo/msgflo#135

[bergie]

OK, so red herring. MsgFlo logged a warning about malformed discovery message, but the restart failed due to msgflo/msgflo#133