Implement option to output information as OpenMetrics time series

This new `-o` option will make needrestart output information in a
format that can be scraped by Prometheus or any other daemon that
ingests OpenMetrics format.

The -l, -w and -k options can be used in combination with -o in order to
choose what information gets exported.

(Closes: #291)

man/needrestart.1

@@ -6,7 +6,7 @@ needrestart checks which daemons need to be restarted after library upgrades.
 .SH USAGE
 Usage:
 .IP
-needrestart [\-(v|q)] [\-n] [\-c <cfg>] [\-r <mode>] [\-f <fe>] [\-u <ui>] [\-(b|p)] [\-kl]
+needrestart [\-(v|q)] [\-n] [\-c <cfg>] [\-r <mode>] [\-f <fe>] [\-u <ui>] [\-(b|p|o)] [\-kl]
 .TP
 \fB\-v\fR
 be more verbose
@@ -49,6 +49,9 @@ enable batch mode
 \fB\-p\fR
 nagios plugin mode: makes output and exit codes nagios compatible
 .TP
+\fB\-o\fR
+OpenMetrics output mode: output information that can be scraped by OpenMetrics-compatible services. Implies batch mode.
+.TP
 \fB\-f\fR <fe>
 override debconf(7) frontend, sets the DEBIAN_FRONTEND environment variable to <fe>
 .TP

needrestart

@@ -84,7 +84,7 @@ sub HELP_MESSAGE {
  print <<USG;
 Usage:
 
- needrestart [-vn] [-c <cfg>] [-r <mode>] [-f <fe>] [-u <ui>] [-bkl]
+ needrestart [-vn] [-c <cfg>] [-r <mode>] [-f <fe>] [-u <ui>] [-(b|p|o)] [-klw]
 
  -v be more verbose
  -q be quiet
@@ -99,6 +99,7 @@ Usage:
  a (a)utomatically restart
  -b enable batch mode
  -p enable nagios plugin mode
+ -o enable OpenMetrics output mode, implies batch mode, cannot be used simultaneously with -p
  -f <fe> override debconf frontend (DEBIAN_FRONTEND, debconf(7))
  -t <seconds> tolerate interpreter process start times within this value
  -u <ui> use preferred UI package (-u ? shows available packages)
@@ -183,11 +184,12 @@ our $opt_f;
 our $opt_k;
 our $opt_l;
 our $opt_p;
+our $opt_o;
 our $opt_q;
 our $opt_t;
 our $opt_u;
 our $opt_w;
-unless(getopts('c:vr:nm:bf:klpqt:u:w')) {
+unless(getopts('c:vr:nm:bf:klpoqt:u:w')) {
  HELP_MESSAGE;
  exit 1;
 }
@@ -240,7 +242,8 @@ $opt_r = 'l' if($opt_m eq 'e');
 $opt_t = $nrconf{tolerance} unless(defined($opt_t));
 
 $nrconf{defno}++ if($opt_n);
-$opt_b++ if($opt_p);
+die "Options -p and -o cannot be defined simultaneously\n" if ($opt_p && $opt_o);
+$opt_b++ if($opt_p || $opt_o);
 
 needrestart_interp_configure({
  perl => {
@@ -456,7 +459,13 @@ my %nagios = (
  uret => 3,
  uperf => q(U),
  );
-print "NEEDRESTART-VER: $NeedRestart::VERSION\n" if($opt_b && !$opt_p);
+print "NEEDRESTART-VER: $NeedRestart::VERSION\n" if($opt_b && !$opt_p && !$opt_o);
+
+my %ometric_kernel_values = (
+ kstatus => q(unknown),
+ krunning => q(unknown),
+ kexpected => q(unknown),
+);
 
 my %restart;
 my %sessions;
@@ -866,12 +875,12 @@ if(defined($opt_k)) {
 
  if(defined($kresult)) {
  if($opt_b) {
- unless($opt_p) {
+ unless($opt_p || $opt_o) {
  print "NEEDRESTART-KCUR: $kvars{KVERSION}\n";
  print "NEEDRESTART-KEXP: $kvars{EVERSION}\n" if(defined($kvars{EVERSION}));
  print "NEEDRESTART-KSTA: $kresult\n";
  }
- else {
+ elsif ($opt_p) {
  $nagios{kstr} = $kvars{KVERSION};
  if($kresult == NRK_VERUPGRADE) {
  $nagios{kstr} .= "!=$kvars{EVERSION}";
@@ -894,6 +903,11 @@ if(defined($opt_k)) {
  $nagios{kstr} .= " (!!)";
  }
  }
+ elsif ($opt_o) {
+ $ometric_kernel_values{kstatus} = ($kresult != NRK_NOUPGRADE ? "outdated" : "current");
+ $ometric_kernel_values{krunning} = $kvars{KVERSION};
+ $ometric_kernel_values{kexpected} = $kvars{EVERSION};
+ }
  }
  else {
  if($kresult == NRK_NOUPGRADE) {
@@ -941,7 +955,7 @@ if(defined($opt_k)) {
 
 if($opt_w) {
  if($opt_b) {
- unless($opt_p) {
+ unless($opt_p || $opt_o) {
  print "NEEDRESTART-UCSTA: $ucode_result\n";
  if($ucode_result != NRM_UNKNOWN) {
  print "NEEDRESTART-UCCUR: $ucode_vars{CURRENT}\n";
@@ -1030,7 +1044,7 @@ if(defined($opt_l) && !$uid) {
  local $nrconf{systemctl_combine} = 1 unless($opt_r eq 'l');
 
  if($opt_b) {
- print "NEEDRESTART-SVC: $rc\n" unless($opt_p);
+ print "NEEDRESTART-SVC: $rc\n" unless($opt_p || $opt_o);
  next;
  }
 
@@ -1205,7 +1219,7 @@ if(defined($opt_l) && !$uid) {
 
  foreach my $cont (sort { lc($a) cmp lc($b) } keys %conts) {
  if($opt_b) {
- print "NEEDRESTART-CONT: $cont\n" unless($opt_p);
+ print "NEEDRESTART-CONT: $cont\n" unless($opt_p || $opt_o);
  next;
  }
 
@@ -1397,6 +1411,37 @@ if($opt_p) {
 
  exit $ret;
 }
+if ($opt_o) {
+ print "# HELP needrestart_build_info information about needrestart's runtime build\n";
+ print "# TYPE needrestart_build_info info\n";
+ print "needrestart_build_info{version=$NeedRestart::VERSION,perl_version=$^V} 1\n";
+
+ my $ometric_now = time();
+ print "# HELP needrestart_timestamp when, in unix timestamp, needrestart was last updated\n";
+ print "# TYPE needrestart_timestamp gauge\n";
+ print "needrestart_timestamp $ometric_now\n";
+
+ if ($opt_k) {
+ print "# HELP needrestart_kernel_info information about the kernel\n";
+ print "# TYPE needrestart_kernel_info info\n";
+ print "needrestart_kernel_info{running=$ometric_kernel_values{krunning},expected=$ometric_kernel_values{kexpected}} $ometric_kernel_values{kstatus}\n";
+ }
+ if ($opt_w) {
+ my $ometric_ucode_current = $ucode_result != NRM_UNKNOWN ? $ucode_vars{CURRENT} : "unknown";
+ my $ometric_ucode_expected = $ucode_result != NRM_UNKNOWN ? $ucode_vars{AVAIL} : "unknown";
+ my $ometric_ucode_status = ("unknown", "current", "obsolete")[$ucode_result];
+ print "# HELP needrestart_ucode_info information about the CPU microcode\n";
+ print "# TYPE needrestart_ucode_info info\n";
+ print "needrestart_ucode_info{running=$ometric_ucode_current,expected=$ometric_ucode_expected} $ometric_ucode_status\n";
+ }
+ if ($opt_l) {
+ my $ometric_num_services = scalar %restart;
+ print "# HELP needrestart_services_count number of services requiring a restart\n";
+ print "# TYPE needrestart_services_count gauge\n";
+ print "needrestart_services_count $ometric_num_services\n";
+ }
+ exit 0;
+}
 
 if ($opt_b and scalar %sessions) {
  for my $sess (@sessions_list) {