Caution: Upgrading Linux openHAB

[papa]

    Introduction

A couple years ago, I installed Linux & openHAB 3 on an older laptop (See here.) When things are going OK, I generally let them run. This is especially true with Linux which I only use for openHAB & Arduino IDE. When one is unfamiliar with something, trying to fix one problem can lead to other problems.

Other than Linux bugging me about updating, the system had been working well. Then a few months ago, my gateways starting losing connection with the MQTT broker (Mosquitto). A Linux reboot & a manual correction of one variable took care of things. However that disconnect problem began reoccurring every month or so. The problem & fix were a little annoying, but could be more serious when I was away from the computer & could not reboot it. The following describes how I tried to fix the problem, how the "fix" did cause (worse) problems, & how I recovered openHAB (I think).

     Next: The Problematic Fix

 

[papa]

        The Problematic Fix

As I said, Linux had bugged me about updating, so I gave that a try in Linux terminal:

sudo apt-get update
sudo apt-get upgrade

 The result was openHAB was broken. I could not get the openHAB interface in my browser. The openHAB log showed many errors.

        What Went Wrong?

Linux upgraded openHAB along with the rest of the installs. Since I had not instructed Linux otherwise, it upgraded my openHAB 3 to the latest openHAB version, an early version of a major upgrade: openHAB 4. According to my research, openHAB 4 is not that reliable yet. Moreover it requires Java 17 not Java 11 as before.

        Next: How I Recovered OpenHAB

[papa]

        How I Recovered OpenHAB

More research suggested downgrading openHAB to a more stable (& compatible) version.

Preliminary precaution: As shown here, I did a backup of my openHAB configuration.

Using Linux Terminal, I followed the downgrading directions in the official openHAB docs:

sudo apt-get update
apt-cache showpkg openhab

Once you know which version you want, you can upgrade/downgrade to it by using the apt-get install openhab=[version] command, for example:

            sudo apt-get install openhab=3.0.0-1

apt-cache showpkg openhab showed several available versions from openHAB 3.0.0-1 to openHAB 4.0.0-1. Before openHAB 4.0.0-1 were versions 3.4.4-2 & 3.4.4-1

            In Linux Terminal, I executed        sudo apt-get install openhab=3.4.4-1

      The results in Linux Terminal:

     Suggested packages:
openjdk-17-jre | java17-runtime | java17-runtime-headless | zulu17-jdk
| temurin-17-jdk

     The following packages will be DOWNGRADED:  openhab
0 upgraded, 0 newly installed, 1 downgraded, 0 to remove and 33 not upgraded

WARNING: We were unable to detect Java 17 on your system. This is needed before openHAB can be started.
[openHAB] Please install the current version of Java 17

    Next: Java 17 ?? & a Working OpenHAB

[papa]

        Java 17 ?? & a Working OpenHAB

From the Terminal message just above, I thought, "Oh, I must install Java 17."  I tried to install the recommended Zulu 17. I was told that there is no version for my machine. Before I tried another flavor of Java 17, I tried to raise the openHAB interface on my browser. Yay, after the openHAB downgrade, everything seems to be working fine. For now, I did not further try to upgrade to Java 17.

    Bottom Line Thoughts

In doing typical Linux updates, openHAB will also be "upgraded," possibly to a broken condition. As shown above, downgrading to a previous openHAB version may fix the problem.

Did my upgrading Linux & openHAB fix the original problem (Gateways disconnecting from the MQTT broker)?  I'll be watching to see

[papa]

        Followup

According to this post & its thread, the warning about Java 17 is wrong. Java 11 is still OK for OpenHAB 3.

Seems like Java 17 might mostly work with openHAB 3, but cause some problems.

        Next: A Different Approach

[papa]

            A Different Approach

Avoid an Update of OpenHAB Until We're Ready

As said earlier, I only use Linux for openHAB & Arduino IDE. So I learn more about Linux when I need it.  I researched how to update Linux, but avoid updating certain packages. This site gave several methods to prevent updating of a specific package. I used only the first method, dpkg. See the following ways to use dpkg.

        Put a package on hold:
echo "<package-name> hold" | sudo dpkg --set-selections

        Remove the hold:
echo "<package-name> install" | sudo dpkg --set-selections

        Display the status of all your packages:
dpkg --get-selections

        Display the status of a single package:
dpkg --get-selections <package-name>

         Show all packages on hold:
dpkg --get-selections | grep "\<hold$"

        Next: Using dpkg with OpenHAB

[papa]

            Using dpkg with OpenHAB

Preliminary precaution: As shown here, do a backup of the openHAB configuration.

                Display the Status of openHAB  (install latest update)

[terminal command:] dpkg --get-selections openhab
[result:] openhab install

            Command openHAB to hold at it's current version

[terminal command:] echo "openhab hold" | sudo dpkg --set-selections
[enter Linux password]

            Display the Status of openHAB (hold, don't update)

[terminal command:] dpkg --get-selections openhab
[result:] openhab hold

            Display All Packages on Hold

[terminal command:] dpkg --get-selections | grep "\<hold$"

[result:] openhab hold

        Next: Update Linux without Breaking OpenHAB

[papa]

            Update Linux without Breaking OpenHAB

            Terminal Commands:

sudo apt-get update
sudo apt-get upgrade

The result from the hold was openHAB was working fine. I could get the openHAB interface in my browser.

Disadvantage: We miss any updates in openHAB 3.  The method in this post could update Linux & the latest openHAB 3 version without breaking openHAB