Hello all,
I am having an issue with TrueNAS Scale’s Portainer app. The end goal is to run two modded minecraft servers, and what I am having trouble with here is just the first one so I will limit the scope to this one. I am new to TrueNAS and Docker, so please correct me if I misunderstood something or haven’t used best practices.
The really short TL;DR is I’d like for someone to help me figure out how to grant the Portainer docker the appropriate permissions to just read and write as it pleases in my dataset pool0/applications. Why I think this is the case, is explained below (but again please correct me if I am barking up the wrong tree).
I have an existing MC server, from which I would like to import the game’s world save files into this docker instance running on TrueNAS. I am using this docker repo inside of Portainer.
I created a Samba share under the path /pool0/applications/mc_vanilla, such that the following docker compose script would create all necessary game files in a dataset that I can access from my Windows machine:
# Generated by setupmc.com on 2025-02-01T09:59:22.644Z
services:
mc:
image: itzg/minecraft-server:latest
tty: true
stdin_open: true
ports:
- "25565:25565"
environment:
EULA: "TRUE"
VERSION: "1.21.4"
volumes:
- "/mnt/pool0/applications/mc_vanilla:/data"
Now, a brand new game world is created just fine at /pool0/applications/mc_vanilla - but the container really doesn’t like it when I try to start the container using existing (imported) game files. I have tried various flavours of this docker compose script, with and without extra arguments, but they all error out in one way or another. In the case of this script (which I have stripped to about as barebones as I want to), the following appears in the container’s console:
[init] Running as uid=1000 gid=1000 with /data as 'drwxrwx--- 8 1000 1000 17 Feb 1 10:44 /data'
[init] Resolving type given VANILLA
[init] Resolved version given 1.21.4 into 1.21.4
[mc-image-helper] 10:48:05.357 INFO : Created/updated 1 property in /data/server.properties
[init] Setting initial memory to 1G and max to 1G
[init] Starting the Minecraft server...
Starting net.minecraft.server.Main
[10:48:08] [ServerMain/INFO]: Environment: Environment[sessionHost=https://sessionserver.mojang.com, servicesHost=https://api.minecraftservices.com, name=PROD]
[10:48:08] [ServerMain/ERROR]: Failed to start the minecraft server
java.nio.file.AccessDeniedException: ./world
at java.base/sun.nio.fs.UnixException.translateToIOException(Unknown Source) ~[?:?]
at java.base/sun.nio.fs.UnixException.asIOException(Unknown Source) ~[?:?]
at java.base/sun.nio.fs.UnixFileSystemProvider.newDirectoryStream(Unknown Source) ~[?:?]
at java.base/java.nio.file.Files.newDirectoryStream(Unknown Source) ~[?:?]
at java.base/java.nio.file.FileTreeWalker.visit(Unknown Source) ~[?:?]
at java.base/java.nio.file.FileTreeWalker.walk(Unknown Source) ~[?:?]
at java.base/java.nio.file.Files.walkFileTree(Unknown Source) ~[?:?]
at java.base/java.nio.file.Files.walkFileTree(Unknown Source) ~[?:?]
at far.b(SourceFile:65) ~[server-1.21.4.jar:?]
at far.a(SourceFile:60) ~[server-1.21.4.jar:?]
at evg.d(SourceFile:349) ~[server-1.21.4.jar:?]
at net.minecraft.server.Main.main(SourceFile:139) ~[server-1.21.4.jar:?]
at net.minecraft.bundler.Main.lambda$run$0(Main.java:54) ~[?:?]
at java.base/java.lang.Thread.run(Unknown Source) [?:?]
2025-02-01T10:48:08.395Z INFO mc-server-runner Done
Where it is plain to see that the docker container app cannot access the ./world file.
As far as I can understand, there is a permissions issue that Java can’t read(?) or modify the files that the docker script didn’t itself create. I was able to verify at least one case of this when the script couldn’t modify an existing server.properties options file but could create and modify a new one just fine.
Of course, I cannot do the same for the ./world file I’m importing to the container, which I really need to persist from my previous Ubuntu Desktop jank-server.
Many thanks for any advice!!
