I have had some problems in general with the way a gateway backup restore handles themes, and they have been a pain in my side for a while.
Essentially the way that a backup restore handles projects, is that if inside of the backup the projects/ directory doesnt exist, it will just do nothing. It will leave the projects directory present on the gateway, and so you can use this to just version control a gateways config, but not the project (if thats managed elsewhere)
However the themes directory unfortunately doesnt work the same way. It seems that on a backup restore, if you have themes it replaces them (which is expected), but if you remove modules/ out of it, then Ignition will assume that it knows the best and just create the files that it would on a regular startup.
This makes it a pain when you have a bunch of theme files you are version controlling, but need to use gateway backups at times to restore your config (which is huge in containers)
I am deploying a handful of gateways in a k8s cluster, and in an ideal world I would have a PVC that contains the contents of my data/modules/com.inductiveautomation.perspective directory, and is mapped into it as such.
Problem is in most scenarios with a container, you have to restore a backup, and so Ignition will do its unceremonious deletion of your files.
So instead I tried to set the PVC to readOnly so that Ignition can't delete, and I figured I could just ignore whatever errors that throws in the logs.
However it causes the gateway to fault 
│ jvm 1 | 2024/10/07 23:27:44 | E [IgnitionGateway ] [23:27:44.485]: Error during context startup. │
│ jvm 1 | 2024/10/07 23:27:44 | java.io.FileNotFoundException: /usr/local/bin/ignition/data/modules/com.inductiveautomation.perspective/fonts/MonaSans/Mona-Sans.wo │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.io.FileOutputStream.open0(Native Method) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.io.FileOutputStream.open(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.io.FileOutputStream.<init>(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.io.FileOutputStream.<init>(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at com.inductiveautomation.ignition.gateway.redundancy.RedundancyManagerImpl.doBasicRestore(RedundancyManagerImpl.java:899) │
│ jvm 1 | 2024/10/07 23:27:44 | at com.inductiveautomation.ignition.gateway.redundancy.RedundancyManagerImpl.startup(RedundancyManagerImpl.java:304) │
│ jvm 1 | 2024/10/07 23:27:44 | at com.inductiveautomation.ignition.gateway.IgnitionGateway.initRedundancy(IgnitionGateway.java:777) │
│ jvm 1 | 2024/10/07 23:27:44 | at com.inductiveautomation.ignition.gateway.IgnitionGateway.lambda$initInternal$1(IgnitionGateway.java:700) │
│ jvm 1 | 2024/10/07 23:27:44 | at com.inductiveautomation.ignition.common.execution.impl.BasicExecutionEngine$ThrowableCatchingRunnable.run(BasicExecutionEngi │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.util.concurrent.FutureTask.run(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | at java.base/java.lang.Thread.run(Unknown Source) │
│ jvm 1 | 2024/10/07 23:27:44 | I [IgnitionGateway ] [23:27:44.487]: Ignition[state=STARTING] ContextState = FAULTED
Any ideas on what to do here? I know one possible path is to inject the themes into your gateway backups, which I can do, but is very hacky for what I am doing here because I dont exactly know when to do that in my pipeline