[check_postgres] New action: warm_standby

[david.barbion at adeoservices.com]

Le 28/06/2011 19:33, Greg Sabino Mullane a écrit :
> On Tue, Jun 28, 2011 at 03:29:05PM +0200, david.barbion at adeoservices.com wrote:
>> 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.
> Thanks! Quick thoughts:
>
> Obviously we'll need a require not a 'use' for the module
> (see for example, the way we handle Date::Parse). I'm not sure about
> the name: we are really checking for a pg_standby process, so
> the "warm_standby" check is indirect.
>
> I'm wondering how this is better than the existing check that scans
> pg_controldata? Also compare with the check_standby_mode() argument...
>
Here is my new patch.
This one takes care of the database cluster state (got from 
pg_controldata in check_standby_mode()).

--- a/check_postgres.pl
+++ b/check_postgres.pl
@@ -946,6 +946,7 @@ our $action_info = {
   new_version_cp      => [0, 'Checks if a newer version of 
check_postgres.pl is available.'],
   new_version_pg      => [0, 'Checks if a newer version of Postgres is 
available.'],
   new_version_tnm     => [0, 'Checks if a newer version of tail_n_mail 
is available.'],
+ pg_standby          => [1, 'Check that postgresql is started in warm 
standby mode (pg_standby process)'],
   pgb_pool_cl_active  => [1, 'Check the number of active clients in 
each pgbouncer pool.'],
   pgb_pool_cl_waiting => [1, 'Check the number of waiting clients in 
each pgbouncer pool.'],
   pgb_pool_sv_active  => [1, 'Check the number of active server 
connections in each pgbouncer pool.'],
@@ -1573,6 +1574,9 @@ check_bloat() if $action eq 'bloat';
  ## Simple connection, warning or critical options
  check_connection() if $action eq 'connection';

+## Check pg_standby process
+check_pg_standby() if $action eq 'pg_standby' ;
+
  ## Check the commitratio of one or more databases
  check_commitratio() if $action eq 'commitratio';

@@ -3559,6 +3563,107 @@ sub check_connection {
  } ## end of check_connection


+sub is_parent_process {
+
+       ## Check that a given PID is the child of another PID
+       ## @arg1: current process table
+       ## @arg2: pid of the parent process
+       ## @arg3: pid of the children 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) ;
+} ## end of is_parent_process
+
+sub check_pg_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');
+    }
+
+    # compute $STANDBY value from pg_controldata output
+    check_standby_mode() ;
+
+    # first check that the cluster is running in standby mode
+    if (!$STANDBY) {
+               add_critical "cluster not in standby mode" ;
+               return;
+       }
+
+    # get current cluster port or default
+    my $port = $ENV{PGPORT} ;
+    $port = $opt{defaultport} if (!$port) ;
+
+    # This function needs the perl module Proc::ProcessTable
+    eval {
+        require Proc::ProcessTable;
+        import DProc::ProcessTable;
+    };
+
+    # retrieve complete process table
+    my $t = new Proc::ProcessTable;
+
+    # First, look for the postmaster process at the specified PGPORT
+    foreach my $p ( @{$t->table} ){
+        if ( $p->cmndline =~ /postmaster.*$port/) {
+            # postmaster process 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" ;
+    }
+
+    return;
+
+} ## end of check_pg_standby
+
+
+
  sub check_custom_query {

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


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