examples: script: cpu.sh - measures CPU usage at a configurable interval

examples/scripts/cpu.sh

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+#!/bin/bash
+
+# cpu.sh - measures CPU usage at a configurable sample interval
+#
+# Usage: cpu.sh INTERVAL_IN_SECONDS
+#
+# This script will emit the following tags on stdout (N is the number
+# of logical CPUs):
+#
+#  Name   Type
+#  --------------------
+#  cpu    range 0-100
+#  cpu0   range 0-100
+#  cpu1   range 0-100
+#  ...
+#  cpuN-1 range 0-100
+#
+# I.e. ‘cpu’ is the average (or aggregated) CPU usage, while cpuX is a
+# specific CPUs usage.
+#
+# Example configuration (update every second):
+#
+#  - script:
+#      path: /path/to/cpu.sh
+#      args: [1]
+#      content: {string: {text: "{cpu}%"}}
+#
+
+interval=${1}
+
+case ${interval} in
+    ''|*[!0-9]*)
+        echo "interval must be an integer"
+        exit 1
+        ;;
+    *)
+        ;;
+esac
+
+# Get number of CPUs, by reading /proc/stat
+# The output looks like:
+#
+#  cpu  A B C D ...
+#  cpu0 A B C D ...
+#  cpu1 A B C D ...
+#  cpuN A B C D ...
+#
+# The first line is a summary line, accounting *all* CPUs
+IFS=$'\n' readarray -t all_cpu_stats < <(grep -e "^cpu" /proc/stat)
+cpu_count=$((${#all_cpu_stats[@]} - 1))
+
+# Arrays of ‘previous’ idle and total stats, needed to calculate the
+# difference between each sample.
+prev_idle=()
+prev_total=()
+for i in $(seq ${cpu_count}); do
+    prev_idle+=(0)
+    prev_total+=(0)
+done
+
+prev_average_idle=0
+prev_average_total=0
+
+while true; do
+    IFS=$'\n' readarray -t all_cpu_stats < <(grep -e "^cpu" /proc/stat)
+
+    usage=()           # CPU usage in percent, 0 <= x <= 100
+    idle=()            # idle time since boot, in jiffies
+    total=()           # total time since boot, in jiffies
+
+    average_idle=0  # All CPUs idle time since boot
+    average_total=0 # All CPUs total time since boot
+
+    for i in $(seq 0 $((cpu_count - 1))); do
+        # Split this CPUs stats into an array
+        stats=($(echo "${all_cpu_stats[$((i + 1))]}"))
+
+        # Clear (zero out) “cpuN”
+        unset "stats[0]"
+
+        # CPU idle time since boot
+        idle[i]=${stats[4]}
+        average_idle=$((average_idle + idle[i]))
+
+        # CPU total time since boot
+        total[i]=0
+        for v in "${stats[@]}"; do
+            total[i]=$((total[i] + v))
+        done
+        average_total=$((average_total + total[i]))
+
+        # Diff since last sample
+        diff_idle=$((idle[i] - prev_idle[i]))
+        diff_total=$((total[i] - prev_total[i]))
+
+        usage[i]=$((100 * (diff_total - diff_idle) / diff_total))
+
+        prev_idle[i]=${idle[i]}
+        prev_total[i]=${total[i]}
+    done
+
+    diff_average_idle=$((average_idle - prev_average_idle))
+    diff_average_total=$((average_total - prev_average_total))
+
+    average_usage=$((100 * (diff_average_total - diff_average_idle) / diff_average_total))
+
+    prev_average_idle=${average_idle}
+    prev_average_total=${average_total}
+
+    echo "cpu|range:0-100|${average_usage}"
+    for i in $(seq 0 $((cpu_count - 1))); do
+        echo "cpu${i}|range:0-100|${usage[i]}"
+    done
+
+    echo ""
+    sleep "${interval}"
+done