title: grafana dashboard for prometheus not working
body: <p>I am newbie to grafana and prometheus. I setup prometheus, grafana, alertmanager, nodeexporter and cadvisor using the docker-compose.yml from this post <a href="https://github.com/vegasbrianc/prometheus" rel="nofollow noreferrer">https://github.com/vegasbrianc/prometheus</a></p>
  
  <p>And imported grafana dashboard #893 from <a href="https://grafana.com/dashboards/893" rel="nofollow noreferrer">https://grafana.com/dashboards/893</a></p>
  
  <p>But the dashboard is not working as I can see N/A in some panels. For example below are the queries used by the panels and I couldn't figure out how to get the values for the template variable in the query. I looked at <a href="http://node-exporter:9100/metrics" rel="nofollow noreferrer">http://node-exporter:9100/metrics</a> and do not see a value for variable '$server'</p>
  
  <pre><code>Query1: time() - node_boot_time{instance=~"$server:.*"}
  Query2:min((node_filesystem_size_bytes{fstype=~"xfs|ext4",instance=~"$server:.*"} - node_filesystem_free_bytes{fstype=~"xfs|ext4",instance=~"$server:.*"} )/ node_filesystem_size_bytes{fstype=~"xfs|ext4",instance=~"$server:.*"})
  </code></pre>
  
  <p>What should I configure for node-exporter and prometheus to evaluate the template variable $server in the queries?</p>