As Red Hat consultant it makes me sad to see the first instruction to install software is to disable SELinux.

It really isn't that hard to learn.

My observium installation (on RHEL 7)

Assuming Observium is installed in /opt/observium

# ensure semange is installed

yum install policycoreutils-python

# set policy to allow apache to write to observium directories

# this could be restricted to read-only on all except rrd & logs.

semanage fcontext -a -t httpd_sys_rw_content_t "/opt/observium(/.*)?"

# apply policy

restorecon -R -v /opt/observium