openHAB With Custom Built Serial Binding – fix to locking permission issue

When we updated our openHAB server to Fedora 28 and changed to a non-root user, the openhab user was unable to create lock files in /run/lock. As an interim fix, we just changed the permission on the lock folder to allow the openhab account to create files. As a more elegant solution, I’ve built the nrjavaserial JAR file from the source in NeuronRobotics’ repository.

The process to build and use a JAR built from this source follows. Before attempting to build the nrjavaserial jar from source, ensure you have gradle (which will install a LOT of additional packages), lockdev, lockdev-devel, some jdk, and some jdk-devel (I used java-1.8.0-openjdk-1.8.0.181-7.b13.fc28.x86_64 and java-1.8.0-openjdk-devel-1.8.0.181-7.b13.fc28.x86_64 because they were already installed for other projects).

# Set ossrhUsername and ossrhPassword values for the account used to build the project – username and password can be null
[lisa@server ~]# cat ~/.gradle/gradle.properties
ossrhUsername=
ossrhPassword=

# Grab the source
[lisa@server ~]# git clone https://github.com/NeuronRobotics/nrjavaserial.git

# Build the project
[lisa@server ~]# cd nrjavaserial
[lisa@server nrjavaserial]# make linux64 # assuming you’ve got 64-bit linux

# Voila, a jar file
[lisa@server nrjavaserial]# cd build/libs
[lisa@server libs]# ll
total 852
-rw-r–r– 1 root root 611694 Aug 16 10:08 nrjavaserial-3.14.0.jar
-rw-r–r– 1 root root 170546 Aug 16 10:08 nrjavaserial-3.14.0-javadoc.jar
-rw-r–r– 1 root root 85833 Aug 16 10:08 nrjavaserial-3.14.0-sources.jar

Before installing the newly built nrjavaserial-3.14.0.jar into openHAB, ensure you have lockdev installed on your Fedora machine and add your openhab user account to the lock group.

# Verify the lockdev folder was created
[lisa@server ~]# ll /run/lock/
total 4
-rw-r–r– 1 root root 22 Aug 10 15:35 asound.state.lock
drwx—— 2 root root 60 Aug 10 15:30 iscsi
drwxrwxr-x 2 root lock 140 Aug 16 12:19 lockdev
drwx—— 2 root root 40 Aug 10 15:30 lvm
drwxr-xr-x 2 root root 40 Aug 10 15:30 ppp
drwxr-xr-x 2 root root 40 Aug 10 15:30 subsys
# Add the openhab user to the lock group
[lisa@server ~]# usermod -a -G lock openhab

The openhab user account can now write to the /run/lock/lockdev folder. Install the new jar file into openHAB. When you restart openHAB, verify lock files are created as expected.
[lisa@server ~]# ll /run/lock/lockdev/
total 20
-rw-rw-r– 5 openhab openhab 11 Aug 16 12:19 LCK…31525
-rw-rw-r– 5 openhab openhab 11 Aug 16 12:19 LCK..ttyUSB-5
-rw-rw-r– 5 openhab openhab 11 Aug 16 12:19 LCK..ttyUSB-55
-rw-rw-r– 5 openhab openhab 11 Aug 16 12:19 LK.000.188.000
-rw-rw-r– 5 openhab openhab 11 Aug 16 12:19 LK.000.188.001

 

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