Is there a right way to update NR from a flow? Calling the official Pi script as a use case? From an exec node? Stop and restart of NR would be required of course. Expect the exec node to queue the task... so the actual Pi script runs as a separate process, which ensures the live NR instance can be shut down gracefully... systemctl stop nodred for example?.

Working on a prototype experiment... Flow invokes bash script (1) via by exec node, sleeps, or watches pid of NR? Flow executes NR stop... yes this kills NR gracefully, so orphans an current active (ui) dashboard session Script (1) spawns Script (2) after sleep, or when pid NR disappears(?) Script (2) runs official Pi script Script (2) starts NR Orphaned (ui) dashboard will try to reconnect? Right? Lost connection logic is to try to reconnect as I recall Ideas, have script (1) archive .node-red directory or key files? Assumptions, NR install is already in place, so settings.js and flows.json exist, and others of course. #!/bin/sh # # Script1.sh # set -e sleep 60 && ./Script2.sh & systemctl stop nodered exit 0 #!/bin/sh # # Script2.sh # set -e echo "Execute Pi NR Script Here" systemctl start nodred exit 0

Have you tried systemctl restart nodered from an exec node? I am not sure what that will do when it is invoked from within the process being restarted. I will see what I can find out.

look a this : [image] [EDIT] Displays if a new Node-Red update is available online, and update it from the Dashboard Share Your Projects This flow will search every 7 days if there is a new online version of Node-Red on https://nodered.org/. If that is the case, [EDIT] : In this new version : 1. Indicates whether a new online version is available. Click on it to start the update : [image] 2. A wheel that turns to make you wait : [image] 3. When the update is complete, you can select: either an automatic restart of NR or (by default) a popup which proposes if you want to restart (or not) in addition to indicating the time ta…

I see that does (on a linux system) does a systemctl restart. I wonder if that is actually safe though, it depends on how it works whether killing the process that is running systemctl can cause problems.

That is why I abstract the restart via a separate script, the first script spawns from exec node, but is not a child process, just invoked by said active process, and shuts down NR. Then calls the install script. Then a spawned second script starts NR post install. By doing this, I am isolating each phase as a different process tree, no child PIDs. This can be done various ways, via cron, sooner, etc. You just have to make sure they are completely separate processes, for the stop and start tasking, and from the original NR instance. The only question I see, is how to watch the sequence appropriately, and once everything is done how to report it back to NR, when NR is alive ago. I may even finalize this via python, so I can hold results and send same to NR via say MQTT as the final status report type of thing.

@SuperNinja Yes, I have my own variant of a 'watch' for new version flow as well. But my variant does not as yet, try to update NR. Will be interesting to see how the update sequence is done. I believe process isolation is the safe way to do any NR initialed NR updating.

If systemctl restart initiates a separate process to do the work, or just sends a message to a long running process then that is simpler and guaranteed to work.

You could use a separate node.js or python script that you run as a systemd service and that communicates with nodered over mqtt. This little service could than do the work of stopping/updating/starting and include error handling or even notify you if something goes wrong.

I have managed to glean some useful information on systemctl. This is from Colin Watson: "systemctl restart" is implemented as sending a single D-Bus method call (RestartUnit) to pid 1, so I believe this will indeed currently work since it's pid 1 that's doing the actual restart work and all that the systemctl process is doing after sending the request is waiting for it to respond. I don't think this implementation detail is officially documented or guaranteed, though, so it might change in future. So it seems it is safe to use systemctll restart to kill oneself at the moment, but might change at some point in the future. I suspect that it is highly unlikely to change within what one might call the foreseeable future.

Yeah, given systemctl has to be all powerful (compared to the services, most anyway) it controls, that model makes sense. There are other ways to control processes up and down the 'ring' scopes... if you know OS design, my reference to rings should be familiar. Recall on DG systems, there was a way to access ring 0, to do an emergency stop, basically a controlled crash of the OS, but as I recall this was somewhat unique to DG OS design at the time... long time ago. :slight_smile: Definitely a 'Don't ever push the red button' type of thing. I think my pid isolation logic is the way to go for now for me... Only because I am curious about how it will work as I create it. That is NOT ignoring the systemctl restart methodology that seems ok to do. Knowing systemctl restart is an option, I would say most should use that method for now if they are considering doing an automated NR update flow (initiator). @JGKK, doing it as a service in the final design definitely is a good idea. Once I get my idea working, will move in that direction. An open question is how I want to 'watch' the progress if at all... for now, NR watching NR does not seem important. Checking for processes that need restart logic I have, Checking for pending reboot logic I have as well, not needed here, but it is part of my current update OS flow. I could just hook NR update into my OS update flow as well, but think I will keep them separate. I don't like cascading changes, makes issue resolution difficult.

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Is there a right way to update NR from a flow?

General

SuperNinja 22 November 2020 08:19 4

look a this :

Topic		Replies	Views
Run raspberry update script from nodered General	10	657	23 April 2021
Updating NR. What I thought should work doesn't General	11	586	4 April 2019
Locking up NR...and escape out from there General	18	2510	10 April 2019
Node-RED user api to restart the application (Node-RED) Core Development	22	956	25 January 2024
Upgrade node red within the flow editor General	7	727	11 June 2019

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Is there a right way to update NR from a flow?

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