#!/usr/bin/perl
# 
#   This is the resource agent used to manage servers on the Anvil! Intelligent Availability platform.
#
#   License: GNU General Public License (GPL) v2+
#            (c) 1997-2018 - Alteeve's Niche! Inc.
# 
# WARNING: This is a pretty purpose-specific resource agent. No effort was made to test this on an rgmanager
#          cluster or on any configuration outside how the Anvil! m3 uses it. If you plan to adapt it to 
#          another purpose, let us know and we'll try to help.
# 
# Based on: https://github.com/ClusterLabs/resource-agents/blob/master/doc/dev-guides/ra-dev-guide.asc
# 
# Error types from pacemaker's perspective;
# 
# - Soft Error -  Unless specifically configured otherwise, pacemaker will attempt to recover a resource 
#                 in-place - usually by restarting the resource on the same node.
# - Hard Error -  Unless specifically configured otherwise, pacemaker will attempt to recover a resource 
#                 which failed with this error by restarting the resource on a different node.
# - Fatal Error - This is a cluster-wide error, it would make no sense to recover such a resource on a 
#                 different node, let alone in-place. When a resource fails with this error, Pacemaker will 
#                 attempt to shut down the resource, and wait for administrator intervention.
# 
# Exit codes;
# 0 - OCF_SUCCESS 
#   - The action completed successfully. This is the expected return code for any successful start, stop, 
#     migrate_to, meta_data, help, and usage action.
#   - For monitor, however, a modified convention applies:
#     - If the server is running we return, OCF_SUCCESS.  If not running and gracefully stopped or migrated 
#       off, return OCF_NOT_RUNNING.
#       
# 1 - OCF_ERR_GENERIC
#   - The action returned a generic error. This is used only when none of the more specific error codes, 
#     defined below, accurately describes the problem.
#   - Pacemaker interprets this exit code as a soft error. 
#     
# 2 - OCF_ERR_ARGS
#   - The resource’s configuration is not valid on this machine. This can happen if the serve fails to boot
#     because of a missing bridge, for example.
#    
# 3 - OCF_ERR_UNIMPLEMENTED
#   - The resource agent was instructed to execute an action that we do not implement.
#   - Not all resource agent actions are mandatory. We don't implement 'promote' or 'demote'. We do implement
#     'migrate_to', 'migrate_from', and 'notify'. If we're misconfigured as a master/slave resource, for 
#     example, then will alert the user about this misconfiguration by returning OCF_ERR_UNIMPLEMENTED.
#     
# 4 - OCF_ERR_PERM 
#   - The action failed due to insufficient permissions. This may be due to a node not being able to open a
#     definition file or resource config. 
#   - Pacemaker interprets this exit code as a hard error. 
#     
# 5 - OCF_ERR_INSTALLED
#   - The action failed because a required component is missing on the node where the action was executed. 
#     This may be due to a required binary not being executable, or a the DRBD resource config file not 
#     existing.
#   - Pacemaker interprets this exit code as a hard error.
#     
# 6 - OCF_ERR_CONFIGURED
#   - The action failed because the user misconfigured the resource in pacemaker. For example, the user may 
#     have configured an alphanumeric string for a parameter that really should be an integer.
#   - Pacemaker interprets this exit code as a fatal error.
#     
# 7 - OCF_NOT_RUNNING
#   - The resource was found not to be running. This is an exit code that may be returned by the monitor 
#     action exclusively. Note that this implies that the resource has either gracefully shut down, or has 
#     never been started.
#     
# 8 - OCF_RUNNING_MASTER
# 9 - OCF_FAILED_MASTER
#   - These OCF exit codes are not used here.
#     

# NOTE: We don't use Anvil::Tools to keep overhead low and to keep this agent independent as possible.
use strict;
use warnings;
use XML::Simple;
use Data::Dumper;

# Turn off buffering so that the pinwheel will display while waiting for the SSH call(s) to complete.
$| = 1;

my $THIS_FILE           =  ($0 =~ /^.*\/(.*)$/)[0];
my $running_directory   =  ($0 =~ /^(.*?)\/$THIS_FILE$/)[0];
if (($running_directory =~ /^\./) && ($ENV{PWD}))
{
	$running_directory =~ s/^\./$ENV{PWD}/;
}

my $conf = {
	'log'		=>	{
		facility	=>	"local0",
		level		=>	2,
		line_numbers	=>	1,
		tag		=>	$THIS_FILE,
	},
	# If a program isn't at the defined path, $ENV{PATH} will be searched.
	path		=>	{
		exe		=>	{
			cibadmin	=>	"/usr/sbin/cibadmin",
			crm_error	=>	"/usr/sbin/crm_error",
			drbdadm		=>	"/usr/sbin/drbdadm",
			echo		=>	"/usr/bin/echo",
			getent		=>	"/usr/bin/getent",
			logger		=>	"/usr/bin/logger",
			stonith_admin	=>	"/usr/sbin/stonith_admin",
		},
	},
	environment	=>	{
		# The name of the server we care about.
		OCF_RESKEY_name		=>	"",
	},
};

# Find executables.
find_executables($conf);

# Get any command line switches.
get_switches($conf);

if (($conf->{switches}{metadaata}) or ($conf->{switches}{'meta-data'}))
{
	show_metadata($conf);
}

# Something for the logs
to_log($conf, {message => "ocf:alteeve:server invoked.", 'line' => __LINE__});


# If we hit here, something very wrong happened.
exit(255);


#############################################################################################################
# Functions                                                                                                 #
#############################################################################################################

# This prints out the metadata and exits.
sub show_metadata
{
	my ($conf) = @_;
	
	# This is a pretty simple agent, by design. We only take a server name for now.
	print '<?xml version="1.0"?>
<!DOCTYPE resource-agent SYSTEM "ra-api-1.dtd">
<resource-agent name="ocs:alteeve:server">
  <version>0.1</version>
  <longdesc lang="en">
This resource agent manages KVM+qemu virtual servers on an Anvil! m3 Intelligent Availability™ system. 
It manages underlying components like DRBD 9 storage resources, brodge connections and so forth.
  </longdesc>
  <shortdesc lang="en">Anvil! m3 server resource agent</shortdesc>
  <parameters>
    <parameter name="name" unique="1" required="1">
      <longdesc lang="en">
        This is the name of the server as reported by virsh.
      </longdesc>
      <shortdesc lang="en">Server name</shortdesc>
      <content type="string"/>
    </parameter>
  </parameters>
  <actions>
    <action name="start"        timeout="30" />
    <action name="stop"         timeout="600" />
    <action name="monitor"      timeout="10" interval="10" depth="0" />
    <action name="notify"       timeout="20" />
    <action name="migrate_to"   timeout="600" />
    <action name="migrate_from" timeout="600" />
    <action name="meta-data"    timeout="5" />
    <action name="validate-all" timeout="20" />
  </actions>
</resource-agent>
';
	
	exit(0);
}

# This gathers command line switches and stores them in 'swithes::<foo>'.
sub get_switches
{
	my ($conf) = @_;
	
	my $last_argument = "";
	foreach my $argument (@ARGV)
	{
		if ($last_argument eq "raw")
		{
			# Don't process anything.
			$conf->{switches}{raw} .= " $argument";
		}
		elsif ($argument =~ /^-/)
		{
			# If the argument is just '--', appeand everything after it to 'raw'.
			if ($argument eq "--")
			{
				$last_argument         = "raw";
				$conf->{switches}{raw} = "";
			}
			else
			{
				($last_argument) = ($argument =~ /^-{1,2}(.*)/)[0];
				if ($last_argument =~ /=/)
				{
					# Break up the variable/value.
					($last_argument, my $value) = (split /=/, $last_argument, 2);
					$conf->{switches}{$last_argument} = $value;
				}
				else
				{
					$conf->{switches}{$last_argument} = "#!SET!#";
				}
			}
		}
		else
		{
			if ($last_argument)
			{
				$conf->{switches}{$last_argument} = $argument;
				$last_argument                    = "";
			}
			else
			{
				# Got a value without an argument. That's OK.
				$conf->{switches}{$argument} = "#!SET!#";
			}
		}
	}
	# Clean up the initial space added to 'raw'.
	if ($conf->{switches}{raw})
	{
		$conf->{switches}{raw} =~ s/^ //;
	}
	
	return(0);
}

# Log file entries
sub to_log
{
	my ($conf, $parameters) = @_;
	
	my $facility = defined $parameters->{facility} ? $parameters->{facility} : $conf->{'log'}{facility};
	my $level    = defined $parameters->{level}    ? $parameters->{level}    : 1;
	my $line     = defined $parameters->{'line'}   ? $parameters->{'line'}   : 0;
	my $message  = defined $parameters->{message}  ? $parameters->{message}  : "";
	my $priority = defined $parameters->{priority} ? $parameters->{priority} : "";
	
	# Leave if we don't care about this message
	return if $level > $conf->{'log'}{level};
	return if not $message;
	
	# Build the message. We log the line
	if (($conf->{'log'}{line_numbers}) && ($line))
	{
		$message = $line."; ".$message;
	}
	
	my $priority_string = $facility;
	if ($priority)
	{
		$priority_string .= ".".$priority;
	}
	elsif ($level eq "0")
	{
		$priority_string .= ".notice";
	}
	elsif (($level eq "1") or ($level eq "2"))
	{
		$priority_string .= ".info";
	}
	else
	{
		$priority_string .= ".debug";
	}
	
	# Clean up the string for bash
	$message =~ s/"/\\\"/gs;
	#$message =~ s/\(/\\\(/gs;
	
	my $shell_call = $conf->{path}{exe}{logger}." --priority ".$priority_string." --tag ".$conf->{'log'}{tag}." -- \"".$message."\"";
	open (my $file_handle, $shell_call." 2>&1 |") or die "Failed to call: [".$shell_call."]. The error was: $!\n";
	while(<$file_handle>)
	{
		# This should not generate output.
		chomp;
		my $line = $_;
		print "Unexpected logging output: [".$line."]\n";
	}
	close $file_handle;

	return(0);
}

# This checks the given paths and, if something isn't found, it searches PATH trying to find it.
sub find_executables
{
	my ($conf) = @_;

	# Variables.
	my $check = "";
	my $bad   = 0;

	# Log entries can only happen if I've found 'logger', so an extra check will be made on 'to_log' 
	# calls.
	my @dirs = split/:/, $ENV{PATH};
	foreach my $exe (sort {$b cmp $a} keys %{$conf->{path}{exe}})
	{
		if ( not -e $conf->{path}{exe}{$exe} )
		{
			to_log($conf, {message => "The program: [$exe] is not at: [".$conf->{path}{exe}{$exe}."]. Looking for it now...", 'line' => __LINE__, level => 1});
			foreach my $path (@dirs)
			{
				$check =  "$path/$exe";
				$check =~ s/\/\//\//g;
				to_log($conf, {message => "Checking: [$check]", 'line' => __LINE__, level => 2});
				if ( -e $check )
				{
					if (-e $conf->{path}{exe}{logger})
					{
						to_log($conf, {message => "Found it! Changed path for: [$exe] from: [".$conf->{path}{exe}{$exe}."] to: [$check]", 'line' => __LINE__, level => 1});
					}
					else
					{
						warn "DEBUG: Found it! Changed path for: [$exe] from: [".$conf->{path}{exe}{$exe}."] to: [$check]\n";
					}
					$conf->{path}{exe}{$exe} = $check;
				}
				else
				{
					to_log($conf, {message => "Not found.", 'line' => __LINE__, level => 2});
				}
			}
		}
		else
		{
			to_log($conf, {message => "Found!", 'line' => __LINE__, level => 3});
			next;
		}

		# Make sure it exists now.
		to_log($conf, {message => "Checking again if: [$exe] is at: [".$conf->{path}{exe}{$exe}."].", 'line' => __LINE__, level => 3});
		if (not -e $conf->{path}{exe}{$exe})
		{
			$bad = 1;
			if (-e $conf->{path}{exe}{logger})
			{
				to_log($conf, {message => "Failed to find executable: [$exe]. Unable to proceed.", 'line' => __LINE__, level => 0});
			}
			else
			{
				warn "Failed to find executable: [$exe]. Unable to proceed.\n";
			}
		}
	}
	if ($bad)
	{
		exit(1);
	}

	return(0);
}