Logstash can't read files it should have access too
It turned out to be related to this bug in upstart:
https://bugs.launchpad.net/upstart/+bug/812870
Because adm
was a secondary group it was not being applied to the process, which is broken as f**k and is apparently fixed in a later version.
My solution was to add setguid adm
to the init file.
Here is a working workaround:
sudo vi /etc/init.d/logstash
modify
LS_GROUP=logstash
by
LS_GROUP=adm
then
sudo /etc/init.d/logstash start