add node_exporter role

roles/node_exporter/files/apt-exporter.pl

@@ -0,0 +1,36 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+my $cmd = "apt-get --just-print dist-upgrade";
+my %metrics;
+
+open(my $fh, '-|', $cmd) or die $!;
+while(my $line = <$fh>) {
+    if ($line =~ /Inst \S+ \S+ \(\S+ (.+) \[(\S+)\]\)/) {
+        my $k = sprintf("apt_upgrades_pending{origin=\"%s\", arch=\"%s\"}", $1, $2); 
+        if (!exists $metrics{$k}) {
+            $metrics{$k} = 1;
+        } else {
+            $metrics{$k}++;
+        }
+    }
+}
+
+if (%metrics) {
+    # print apt metrics
+    while(my($k, $v) = each %metrics) {
+        printf("%s %d\n", $k, $v)
+    }
+}
+else {
+    print("apt_upgrades_pending{origin=\"\",arch=\"\"} 0\n");
+}
+
+# print reboot required metric
+if (-e "/var/run/reboot-required") {
+    print("node_reboot_required 1\n")
+}
+else {
+    print("node_reboot_required 0\n")
+}

roles/node_exporter/files/promcat.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+
+function usage { printf "Usage: %s FILE\n" "$(basename "$0")" >&2; exit 1; }
+
+while getopts "h" opt; do
+    case "${opt}" in
+        *)
+            usage
+            ;;
+    esac
+done
+shift $((OPTIND-1))
+
+FILE="$1"
+
+if [ -z "${FILE}" ]; then
+    usage
+    exit 1
+fi
+
+if command -v sponge > /dev/null; then
+    ( echo "# promcat (sponge)" ; cat /dev/stdin ) | sponge "${FILE}"
+else
+    TEMP=$(mktemp --suffix .prom)
+
+    function finish {
+        if [ -f "${TEMP}" ]; then
+            rm -f "${TEMP}"
+        fi
+    }
+    trap finish EXIT
+
+    echo "# promcat (mktemp, mv)" > "${TEMP}"
+    cat /dev/stdin >> "${TEMP}"
+
+    if [ ! -s "${TEMP}" ] || grep -q '^[[:space:]]*$' "${TEMP}" ; then
+        printf "%s is empty\n" "${TEMP}" >&2
+        exit 1
+    else
+        mv "${TEMP}" "${FILE}"
+    fi
+fi