[check_postgres] New action: warm_standby

[david.barbion at adeoservices.com]

Hello,

I've created a small patch for check_postgres.pl that adds a new action: 
warm_standby.
This action checks that the process pg_standby is running for the 
current cluster (depending on the PGPORT env var.).
This patch needs the perl module Proc::ProcessTable available at CPAN.

Any comments appreciated!

Best Regards,
David.

--- ./check_postgres.pl.orig    2011-06-27 11:56:55.000000000 +0200
+++ ./check_postgres.pl    2011-06-27 13:06:30.000000000 +0200
@@ -887,6 +887,7 @@
   txn_wraparound      => [1, 'See how close databases are getting to 
transaction ID wraparound.'],
   version             => [1, 'Check for proper Postgres version.'],
   wal_files           => [1, 'Check the number of WAL files in the 
pg_xlog directory'],
+ warm_standby        => [1, 'Check that postgresql is started in warm 
standby mode (pg_standby)'],
  };

  ## XXX Need to i18n the above
@@ -1410,6 +1411,9 @@
  ## Simple connection, warning or critical options
  check_connection() if $action eq 'connection';

+## Check warm_standby mode
+check_warm_standby() if $action eq 'warm_standby' ;
+
  ## Check the size of one or more databases
  check_database_size() if $action eq 'database_size';

@@ -3141,6 +3145,97 @@
  } ## end of check_connection


+sub is_parent_process {
+    my $process_table_ref = shift ;
+    my @process_table = @$process_table_ref ;
+    my $parent_pid = shift ;
+    my $child_pid = shift ;
+
+    return(0) if($child_pid == 1) ;
+
+    foreach my $p ( @process_table){
+        if ( $p->pid == $child_pid) {
+            # found !
+            if ($p->ppid == $parent_pid) {
+                return(1) ;
+            }else {
+                if (is_parent_process(\@process_table, $parent_pid, 
$p->ppid) == 1) {
+            return(1) ;
+                }
+            }
+        }
+    }
+    return(0) ;
+}
+
+sub check_warm_standby {
+
+    ## Check that postgresql is started in warm standby mode
+    ## Look at the process table for pg_standby command
+    ## No comparisons made: warning and critical are not allowed
+    ## Suports: Nagios, MRTG
+
+    my $postmaster_pid = 0;
+    my $pg_standby_pid = 0;
+    my $found = 0 ;
+
+    if ($opt{warning} or $opt{critical}) {
+        ndie msg('range-none');
+    }
+
+    # get current cluster port or default
+    my $port = $ENV{PGPORT} ;
+    $port = $opt{defaultport} if (!$port) ;
+
+    # FIX: We should return an error if this module not present
+    use Proc::ProcessTable ;
+
+    my $t = new Proc::ProcessTable;
+    #printf($FORMAT, "PID", "TTY", "STAT", "START", "COMMAND");
+    # First, look for the postmaster process at the specified PGPORT
+    foreach my $p ( @{$t->table} ){
+        #print $p->pid." ".$p->ppid." ".$p->cmndline."\n" ;
+        if ( $p->cmndline =~ /postmaster.*$port/) {
+            # found !
+            $postmaster_pid = $p->pid ;
+        }
+    }
+    if ($postmaster_pid == 0) {
+        add_critical "Postmaster PID not found for port $port" ;
+        return ;
+    }
+
+    # Then, look for the pg_standby
+    foreach my $p ( @{$t->table} ){
+        if ( $p->cmndline =~ /pg_standby/) {
+            # found !
+            $pg_standby_pid = $p->pid ;
+            if (is_parent_process(\@{$t->table}, $postmaster_pid, 
$pg_standby_pid) == 1) {
+        # pg_standby running
+        $found = $pg_standby_pid ;
+        }
+        }
+    }
+    if (!$found) {
+        add_critical "pg_standby not running" ;
+    }else {
+        add_ok "pg_standby($found) running" ;
+    }
+    ####
+    #$MRTG and do_mrtg({one => $ver ? 1 : 0});
+
+    #if ($ver) {
+    #    add_ok msg('version', $ver);
+    #}
+    #else {
+    #    add_unknown msg('invalid-query', $db->{slurp}[0]{v});
+    #}
+
+    return;
+
+} ## end of check_connection
+
+
  sub check_custom_query {

      ## Run a user-supplied query, then parse the results


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