These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.
The files are initially created by nginx as 0644/http:root, but when
logrotate rotates the files it creates the new files as 0640/http:log,
which promtail can't read.
Fix the issue by adding the log group as a supplementary group.
A extra access_log entry was added with the following commands:
$ cd roles
$ grep -lr access_log | xargs -P 1 -n 1 sed -i '/access_log/ s/\(.*\)\( \)\(\(reduced\|main\);$\)/\1 \3\n\1.json json_\3/'
