point to right IP

monitoring/README.md

@@ -5,35 +5,41 @@ https://grafana.com/grafana/dashboards/11858
 
 A `docker-compose` script for ingesting `collectd` output from OpenWRT to InfluxDB, and using Grafana to build pretty dashboards.
 
-It's networked, so it doesn't need to be run on the same machine as OpenWRT, but it probably should.
+Docker assigns IP addresses sequentially. By default OpenWRT assigns DHCP addresses with an offset of 100, so we have a very high chance that the Docker-assigned addresses will not overlap the OpenWRT DHCP addresses. But it's something we need to be aware of.
 
 
 ## Steps
 
+### On host
+
+* launch InfluxDB and Grafana
+```
+$ docker-compose up -d
+```
+
+* get InfluxDB IP address
+```
+$ INFLUXDB_HOST=$(docker inspect monitoring_influxdb_1 -f '
+  {{- range .NetworkSettings.Networks}}
+  {{- .IPAddress -}}
+  {{end -}}')
+
+$ echo $INFLUXDB_HOST
+```
+
 ### On OpenWRT
 * Install `collectd` and any additional plugins you want (`collectd-mod-*`) on OpenWRT, plus `luci-app-statistics` for configuration from LuCI
 ```
 # opkg install luci-app-statistics collectd
 ```
 
-* Set up network export (make sure `LAN_HOST` is set)
+* Set up network export (make sure `INFLUXDB_HOST` from above is set)
 ```
 # cat <<EOF | uci batch
 set luci_statistics.influxdb=collectd_network_server
 set luci_statistics.influxdb.port='25826'
-set luci_statistics.influxdb.host="${LAN_HOST}"
+set luci_statistics.influxdb.host="${INFLUXDB_HOST}"
 EOF
-$ uci commit
-$ /etc/init.d/luci_statistics restart
-```
-### On host
-* get `types.db` (not sure if this is totally necessary)
-```
-$ scp openwrt.home:/usr/share/collectd/types.db \
-  influxdb/
-```
-
-* from the host, launch InfluxDB and Grafana
-```
-$ docker-compose up -d
-```
+# uci commit
+# /etc/init.d/luci_statistics restart
+```