Description of problem:
EL6 read from /etc/sysconfig for options. EL7 does not.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. yum install rng-tools
2. note that /etc/sysconfig/rngd is missing.
3. populate /etc/sysconfig/rngd with info, and note that it is unused.
rngd loads without any environment set.
rngd in el7 behaves like el6.
Trivial fix. Modify the .service file as follows:
$ cat rngd.service
Description=Hardware RNG Entropy Gatherer Daemon
ExecStart=/sbin/rngd -f $EXTRAOPTIONS
$ sudo cat /etc/sysconfig/rngd
# Add extra options here
The EnvironmentFile isn't needed. Since all the behvioral options are passed to rngd on the command line, you should just copy the rngd.service file to /etc/systemd/system/rngd.service and add the desired options directly to the ExecStart line in the unit file. It saves the indirection of an environment variable and is the recommended method for doing so.