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--- prometheus [2024/02/07 17:34] – ssm2017
+++ prometheus [2025/09/09 09:33] (current) – [rpi temperature] ssm2017
@@ Line 197: / Line 197: @@
     security_level: authPriv
     auth_protocol: MD5
-    username: snmp-exporter
+    username: myusername
-    password: 5nmp-3xp02732
+    password: mypassword
     priv_protocol: DES
-    priv_password: P21v-p2070c0l
+    priv_password: otherpassword
 modules:
   synology:
@@ Line 2969: / Line 2969: @@
       community: synology
 </sxh>
+==== rpi temperature ====
+source : brave
+prompt :
+<sxh>write  a script with node_exporter's textfile collector. This script reads the temperature from /sys/class/thermal/thermal_zone0/temp and writes it to a file in a format that node_exporter can scrape like /var/log/node_exporter</sxh>
+answer :
+Here's a simple Bash script that reads the Raspberry Pi's CPU temperature and writes it in Prometheus format to a file that `node_exporter` can scrape via the **textfile collector**:
+<sxh bash>
+#!/bin/bash
+# Output directory for node_exporter textfile collector
+OUTPUT_DIR="/var/lib/node_exporter/textfile_collector"
+OUTPUT_FILE="$OUTPUT_DIR/rpi_cpu_temp.prom"
+# Check if output directory exists
+if [ ! -d "$OUTPUT_DIR" ]; then
+  echo "Error: Directory $OUTPUT_DIR does not exist. Please create it and ensure node_exporter has read access."
+  exit 1
+fi
+# Check if we can write to the directory
+if [ ! -w "$OUTPUT_DIR" ]; then
+  echo "Error: No write permission to $OUTPUT_DIR"
+  exit 1
+fi
+# Read raw temperature (in millidegrees Celsius)
+TEMP_MILLI=$(cat /sys/class/thermal/thermal_zone0/temp 2>/dev/null)
+if [ -z "$TEMP_MILLI" ]; then
+  echo "Error: Could not read temperature from /sys/class/thermal/thermal_zone0/temp"
+  exit 1
+fi
+# Convert to degrees Celsius
+TEMP_C=$(echo "scale=2; $TEMP_MILLI / 1000" | bc -l)
+# Write metric to temporary file then move (atomic write)
+TEMP_FILE="$OUTPUT_FILE.tmp"
+cat > "$TEMP_FILE" << EOF
+# HELP rpi_cpu_temperature_celsius CPU temperature of the Raspberry Pi
+# TYPE rpi_cpu_temperature_celsius gauge
+rpi_cpu_temperature_celsius $TEMP_C
+EOF
+mv "$TEMP_FILE" "$OUTPUT_FILE"
+exit 0
+</sxh>
+=== ✅ Setup Instructions ===
+  - 1. **Save the script** (e.g., as `/usr/local/bin/rpi_temp.sh`):
+<sxh bash>
+sudo nano /usr/local/bin/rpi_temp.sh
+</sxh>
+  - 2. **Make it executable**:
+<sxh bash>
+sudo chmod +x /usr/local/bin/rpi_temp.sh
+</sxh>
+  - 3. **Ensure the textfile collector directory exists**:
+<sxh bash>
+sudo mkdir -p /var/lib/node_exporter/textfile_collector
+</sxh>
+  - 4. **Verify node_exporter is running with the textfile collector enabled** (it is enabled by default). You can confirm with:
+<sxh bash>
+node_exporter --help | grep textfile
+</sxh>
+You should see something like:
+<sxh>
+   --collector.textfile.directory string   If set, will source metrics via text files in this directory, one per file.
+</sxh>
+then
+<sxh bash>
+systemctl daemon-reexec
+</sxh>
+  - 5. **Run the script manually to test**:
+<sxh bash>
+sudo /usr/local/bin/rpi_temp.sh
+</sxh>
+Then check the output:
+<sxh bash>
+cat /var/lib/node_exporter/textfile_collector/rpi_cpu_temp.prom
+</sxh>
+Output should look like:
+<sxh>
+# HELP rpi_cpu_temperature_celsius CPU temperature of the Raspberry Pi
+# TYPE rpi_cpu_temperature_celsius gauge
+rpi_cpu_temperature_celsius 42.3
+</sxh>
+  - 6. **Set up a cron job to run every minute**:
+<sxh>
+sudo crontab -e
+</sxh>
+Add this line:
+<sxh>
+* * * * * /usr/local/bin/rpi_temp.sh 2>&1
+</sxh>
+⚠️ Run as root or a user with access to '/sys/class/thermal/thermal_zone0/temp'.
+=== ✅ Prometheus Metric ===
+After setup, the metric will be available at your 'node_exporter' metrics endpoint (usually 'http://<pi-ip>:9100/metrics') as:
+<sxh>
+rpi_cpu_temperature_celsius
+</sxh>
+You can now graph or alert on this in Prometheus or Grafana.
+=== 📝 Notes ===
+  * The default `node_exporter` textfile directory is often `/var/lib/node_exporter/textfile_collector`. Adjust if your system uses a different path (e.g., `/var/log/node_exporter`).
+  * Ensure the user running the script can read `/sys/class/thermal/thermal_zone0/temp`.
+  * Using `bc` allows for decimal math. Install it with `sudo apt install bc` if needed.