* check at startup that existing RRD files conform to the config specifications -- niko

  - new Smokeping::RRDtools module
  - note in CHANGES and smokeping_upgrade

2 files changed, 177 insertions, 2 deletions

diff --git a/lib/Smokeping.pm b/lib/Smokeping.pm
index 65ac92b..82113a3 100644
--- a/lib/Smokeping.pm
+++ b/lib/Smokeping.pm
@@ -16,6 +16,7 @@ setlogsock('unix')
    if grep /^ $^O $/xo, ("linux", "openbsd", "freebsd", "netbsd");
 use File::Basename;
 use Smokeping::Examples;
+use Smokeping::RRDtools;
 
 # globale persistent variables for speedy
 use vars qw($cfg $probes $VERSION $havegetaddrinfo $cgimode);
@@ -359,8 +360,7 @@ sub init_target_tree ($$$$) {
 	    }
 	    my $pings = $probeobj->_pings($tree);
 
-	    if (not -f $name.".rrd"){
-	    	my @create = 
+	   my @create = 
 			($name.".rrd", "--step",$step,
 			      "DS:uptime:GAUGE:".(2*$step).":0:U",
 			      "DS:loss:GAUGE:".(2*$step).":0:".$pings,
@@ -369,10 +369,16 @@ sub init_target_tree ($$$$) {
 			      (map { "DS:ping${_}:GAUGE:".(2*$step).":0:180" }
 			                                                  1..$pings),
 			      (map { "RRA:".(join ":", @{$_}) } @{$cfg->{Database}{_table}} ));
+	    if (not -f $name.".rrd"){
 		do_debuglog("Calling RRDs::create(@create)");
 		RRDs::create(@create);
 		my $ERROR = RRDs::error();
 		do_log "RRDs::create ERROR: $ERROR\n" if $ERROR;
+	    } else {
+	    	shift @create; # remove the filename
+	    	my $comparison = Smokeping::RRDtools::compare($name.".rrd", \@create);
+		die("Error: RRD parameter mismatch ('$comparison'). You must delete $name.rrd or fix the configuration parameters.\n")
+			if $comparison;
 	    }
 	}
     }
diff --git a/lib/Smokeping/RRDtools.pm b/lib/Smokeping/RRDtools.pm
new file mode 100644
index 0000000..7260cca
--- /dev/null
+++ b/lib/Smokeping/RRDtools.pm
@@ -0,0 +1,169 @@
+package Smokeping::RRDtools;
+
+=head1 NAME
+
+Smokeping::RRDtools - Tools for RRD file handling
+
+=head1 SYNOPSYS
+
+ use Smokeping::RRDtools;
+ use RRDs;
+
+ my $file = '/path/to/file.rrd';
+
+ # get the create arguments that $file was created with
+ my $create = Smokeping::RRDtools::info2create($file);
+
+ # use them to create a new file
+ RRDs::create('/path/to/file2.rrd', @$create);
+
+ # or compare them against another create list
+ my @create = ('--step', 60, 'DS:ds0:GAUGE:120:0:U', 'RRA:AVERAGE:0.5:1:1008');
+ my $comparison = Smokeping::RRDtools::compare($file, \@create);
+ print "Create arguments didn't match: $comparison\n" if $comparison;
+
+=head1 DESCRIPTION
+
+This module offers two functions, C<info2create> and C<compare>.
+The first can be used to recreate the arguments that an RRD file
+was created with. The second checks if an RRD file was created
+with the given arguments.
+
+The function C<info2create> must be called with one argument:
+the path to the interesting RRD file. It will return an array
+reference of the argument list that can be fed to C<RRDs::create>.
+Note that this list will never contain the C<start> parameter,
+but it B<will> contain the C<step> parameter.
+
+The function C<compare> must be called with two arguments: the path
+to the interesting RRD file, and a reference to an argument list that
+could be fed to C<RRDs::create>. The function will then simply compare
+the result of C<info2create> with this argument list.  It will return
+C<undef> if the arguments matched, and a string indicating the difference
+if a discrepancy was found. Note that if there is a C<start> parameter in
+the argument list, C<compare> disregards it. If C<step> isn't specified,
+C<compare> will use the C<rrdtool> default of 300 seconds.
+
+=head1 NOTES
+
+This module is not particularly specific to Smokeping, it is just
+distributed with it.
+
+=head1 BUGS
+
+Probably.
+
+=head1 COPYRIGHT
+
+Copyright (c) 2005 by Niko Tyni.
+
+=head1 LICENSE
+
+This program is free software; you can redistribute it
+and/or modify it under the terms of the GNU General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be
+useful, but WITHOUT ANY WARRANTY; without even the implied
+warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+PURPOSE.  See the GNU General Public License for more
+details.
+
+You should have received a copy of the GNU General Public
+License along with this program; if not, write to the Free
+Software Foundation, Inc., 675 Mass Ave, Cambridge, MA
+02139, USA.
+
+=head1 SEE ALSO
+
+RRDs(3)
+
+=cut
+
+use strict;
+use RRDs;
+
+# take an RRD file and make a create list out of it
+sub info2create {
+	my $file = shift;
+	my @create;
+	my $info = RRDs::info($file);
+	my $error = RRDs::error;
+	die("RRDs::info $file: ERROR: $error") if $error;
+	die("$file: unknown RRD version: $info->{rrd_version}")
+		unless $info->{rrd_version} eq '0001';
+	my $cf = $info->{"rra[0].cf"};
+	die("$file: no RRAs found?") 
+		unless defined $cf;
+	my @fetch = RRDs::fetch($file, $cf);
+	$error = RRDs::error;
+	die("RRDs::fetch $file $cf: ERROR: $error") if $error;
+	my @ds = @{$fetch[2]};
+
+	push @create, '--step', $info->{step};
+	for my $ds (@ds) {
+		my @s = ("DS", $ds);
+		for (qw(type minimal_heartbeat min max)) {
+			die("$file: missing $_ for DS $ds?")
+				unless exists $info->{"ds[$ds].$_"};
+			my $val = $info->{"ds[$ds].$_"};
+			push @s, defined $val ? $val : "U";
+		}
+		push @create, join(":", @s);
+	}
+	for (my $i=0; exists $info->{"rra[$i].cf"}; $i++) {
+		my @s = ("RRA", $info->{"rra[$i].cf"});
+		for (qw(xff pdp_per_row rows)) {
+			die("$file: missing $_ for RRA $i")
+				unless exists $info->{"rra[$i].$_"};
+			push @s, $info->{"rra[$i].$_"};
+		}
+		push @create, join(":", @s);
+	}
+	return \@create;
+}
+
+sub compare {
+	my $file = shift;
+	my $create = shift;
+	my @create2 = @{info2create($file)};
+	my @create = @$create; # copy because we change it
+	# we don't compare the '--start' param
+	if ($create[0] eq '--start') {
+		shift @create;
+		shift @create;
+	}
+	# special check for the optional 'step' parameter
+	die("Internal error: didn't get the step parameter from info2create?")
+		unless ("--step" eq shift @create2);
+	my $step = shift @create2;
+	my $step2;
+	if ($create[0] eq '--step') {
+		shift @create;
+		$step2 = shift @create;
+	} else {
+		$step2 = 300; # default value
+	}
+	return "Wrong value of step: $file has $step, create string has $step2"
+		unless $step == $step2;
+	
+	my $dscount = grep /^DS/, @create;
+	my $dscount2 = grep /^DS/, @create2;
+	return "Different number of data sources: $file has $dscount2, create string has $dscount"
+		unless $dscount == $dscount2;
+	my $rracount = grep /^RRA/, @create;
+	my $rracount2 = grep /^RRA/, @create2;
+	return "Different number of RRAs: $file has $rracount2, create string has $rracount"
+		unless $rracount == $rracount2;
+
+	while (my $arg = shift @create) {
+		my $arg2 = shift @create2;
+		return "Different arguments: $file has $arg2, create string has $arg"
+			unless $arg eq $arg2;
+	}
+	return undef;
+}
+
+1;