Exception in Fuseki initialization: `FUSEKI_BASE` is not writable

[chrysle]

Related to #56 and #61

Running the image with this command:

$ sudo docker run \
    --detach \
    --publish 3030:3030 \
    --name fuseki-test \
    --env ADMIN_PASSWORD=some-password \
    --volume /some/mount/location:/fuseki \
    stain/jena-fuseki:latest \
    /jena-fuseki/fuseki-server --loc=/fuseki --update /ds

Results in the following exception:

$ docker logs fuseki-test 
/docker-entrypoint.sh: line 43: can't create /fuseki/shiro.ini.7: Permission denied
Waiting for Fuseki to finish starting up...
07:44:40 INFO  Server          :: Apache Jena Fuseki 4.8.0
07:44:41 INFO  Config          :: FUSEKI_HOME=/jena-fuseki
07:44:41 INFO  Config          :: FUSEKI_BASE=/fuseki
07:44:41 ERROR Server          :: Exception in server initialization
org.apache.jena.fuseki.FusekiConfigException: FUSEKI_BASE is not writable: /fuseki

The web interface at http://localhost:3030/ returns the same HTTP response as in the linked issues.
I'm experiencing this on Ubuntu Linux 20.04.05.

[rmeissn]

See #78 (comment) for how to resolve this issue.