Mention copr yum repository, add systemd unit (prometheus#529)

* add systemd unit as example

* mention community yum repo

fixes prometheus#498

* rename textfile collector dir

README.md

@@ -136,3 +136,13 @@ As a general rule of thumb, please try to create bug reports that are:
 - *Specific.* Include as much detail as possible: which version, what environment, etc.
 - *Unique.* Do not duplicate existing tickets.
 - *Scoped to a Single Bug.* One bug per report.
+
+## Using a third-party repository for RHEL/CentOS/Fedora
+
+There is a [community-supplied COPR repository](https://copr.fedorainfracloud.org/coprs/ibotty/prometheus-exporters/). It closely follows upstream releases.
+
+[travis]: https://travis-ci.org/prometheus/node_exporter
+[hub]: https://hub.docker.com/r/prom/node-exporter/
+[circleci]: https://circleci.com/gh/prometheus/node_exporter
+[quay]: https://quay.io/repository/prometheus/node-exporter
+[goreportcard]: https://goreportcard.com/report/github.com/prometheus/node_exporter

examples/systemd/README.md

@@ -0,0 +1,8 @@
+# Systemd Unit
+
+If you are using distribution packages or the copr repository, you don't need to deal with these files!
+
+The unit file in this directory is to be put into `/etc/systemd/system`.
+It needs a user named `node_exporter`, whose shell should be `/sbin/nologin` and should not have any special privileges.
+It needs a sysconfig file in `/etc/sysconfig/node_exporter`.
+A sample file can be found in `sysconfig.node_exporter`.

examples/systemd/node_exporter.service

@@ -0,0 +1,10 @@
+[Unit]
+Description=Node Exporter
+
+[Service]
+User=node_exporter
+EnvironmentFile=/etc/sysconfig/node_exporter
+ExecStart=/usr/sbin/node_exporter $OPTIONS
+
+[Install]
+WantedBy=multi-user.target

examples/systemd/sysconfig.node_exporter

@@ -0,0 +1 @@
+OPTIONS="-collector.textfile.directory /var/lib/node_exporter/textfile_collector"