update documentation

README-grafana.md

@@ -6,6 +6,19 @@ In this guide we will be using [`Prometheus`](https://prometheus.io/) as the dat
 
 Using Grafana and Prometheus in this configuration does not require a plan, account, or credentials for their respective cloud offerings.
 
+## Ultrafeeder Image Tag
+
+When using the `:telegraf` tag, the image contains [Telegraf](https://docs.influxdata.com/telegraf/), which can be used to capture metrics from `readsb` if an output is enabled.
+
+**NOTE - READ CAREFULLY**: As of 27 April 2023, the `latest` image no longer container Telegraf. If you want to send metrics to InfluxDB or Prometheus, please use the `:telegraf` tag like this in your `docker-compose.yml` file:
+
+```yaml
+services:
+  tar1090:
+    image: ghcr.io/sdr-enthusiasts/docker-tar1090:telegraf
+  ...
+```
+
 ## Hardware requirements
 
 Prometheus will store a lot of data, and Grafana will do a lot of data queries. As a result, it would be better if you run these containers on a different system than your feeder Raspberry Pi. This will leave your Pi focused on data collection and processing, and unbothered by the CPU and Disk IO load that Prometheus/Grafana will cause.

README.md

@@ -594,7 +594,18 @@ Generally, there is little to configure, but there are a few parameters that you
 
 ## Metrics
 
-This image contains [Telegraf](https://docs.influxdata.com/telegraf/), which will be used to capture metrics from `readsb` if an output is enabled.
+When using the `:telegraf` tag, the image contains [Telegraf](https://docs.influxdata.com/telegraf/), which can be used to capture metrics from `ultrafeeder` if an output is enabled.
+
+See [README-grafana.md](README-grafana.md) for detailed instruction on how to configure this.
+
+**NOTE - READ CAREFULLY**: As of 27 April 2023, the `latest` image no longer container Telegraf. If you want to send metrics to InfluxDB or Prometheus, please use this image:
+
+```yaml
+services:
+  tar1090:
+    image: ghcr.io/sdr-enthusiasts/docker-tar1090:telegraf
+  ...
+```
 
 ### Output to InfluxDBv2
 

docker-compose.yml

@@ -1,6 +1,9 @@
 services:
   ultrafeeder:
     image: ghcr.io/sdr-enthusiasts/docker-adsb-ultrafeeder
+    # Note - if you want to enable telegraf for use with InfluxDB/Prometheus and Grafana,
+    # use the following image instead:
+    # image: ghcr.io/sdr-enthusiasts/docker-adsb-ultrafeeder:telegraf
     tty: true
     container_name: ultrafeeder
     hostname: ultrafeeder
@@ -84,6 +87,7 @@ services:
       # 
       # --------------------------------------------------
       # Prometheus and InfluxDB connection parameters:
+      # (See above for the correct image tag you must use to enable this)
       - INFLUXDBV2_URL=${INFLUX_URL}
       - INFLUXDBV2_TOKEN=${INFLUX_TOKEN}
       - INFLUXDBV2_BUCKET=${INFLUX_BUCKET}