#!/usr/bin/perl

use Net::Amazon::EC2;

##--------------------------------------------------------------
##  This must be set to something valid ...

my $MY_AWS_ACCESS_KEY_ID     = "";
my $MY_AWS_SECRET_ACCESS_KEY = "";
my $EXTERNAL_DNS_SERVER = "";
##--------------------------------------------------------------


##
## This is a rough script for making EC2 server changes necessary
## to allow a full automatic installation of UniCluster Express
## to occur. Use at your own risk. 
##
## This is the summary of changes that are made:
##
## (1) Replace existing /etc/hosts with one that explicitly
##     lists the public and private hostnames of the EC2 instance
##
## (2) Change the hostname of the EC2 instance from the private name
##     to the public "...amazonaws.com" name
##
## (3) EC2 instances only have a private internal IP that gets NATed
##     when communicating outside of the cloud. In order to configure
##     Globus GridFTP to work properly we need to capture the IP address
##     used as a source for outbound traffic from this node. This info is
##     captured via a DNS lookup on the public hostname and then written
##     into a file at /etc/sysconfig/EC2-public-IPaddr so that it can be
##     grabbed and used by a post-install script that refines the GridFTP
##     server configuration located in /etc/xinetd.d/unicluster-gridftp
##
##     Chris Dagdigian / BioTeam / chris@bioteam.net
##  

my $hosttype = shift @ARGV;


print "(########) 1 \n";

# Learn our own internal hostname (which is the AWS internal name)
my $hostname            = `/bin/hostname` ;
chomp $hostname;
$sh_hostname = $hostname;
$hostname .= ".ec2.internal";

my $reservation_hosts = {};
my $host_reservations = {};
#my $aws_access_key_id     = $ENV{'AWS_ACCESS_KEY_ID'};
#my $aws_secret_access_key = $ENV{'AWS_SECRET_ACCESS_KEY'};

my $ec2 = Net::Amazon::EC2->new(
                AWSAccessKeyId => $MY_AWS_ACCESS_KEY_ID,
                SecretAccessKey => $MY_AWS_SECRET_ACCESS_KEY
        );

print "(########) 2 \n";

my $instances = $ec2->describe_instances;

if (ref($instances) eq "Net::Amazon::EC2::Errors") {
	print "\nAWS ERROR!\n";
	print "request_id: $instances->{request_id}\n";
	foreach $error (@{$instances->{errors}}) {
		print "code: $error->{code}\n";
		print "message: $error->{message}\n";
	}
}


foreach my $reservation (@$instances) {
    foreach my $instance ($reservation->instances_set) {

	$instance_hostname = $instance->private_dns_name;
	$public_hostname   = $instance->dns_name;
	($sh_public_hostname,$junk)  = split(/\./,$public_hostname);

	print "(########) Comparing:  $instance_hostname vs. $hostname \n";
	if ($hostname eq $instance_hostname) { 

	    # If we get here than we are working our own instance
	    print "My internal hostname: $hostname\n";
	    print "My instance hostname: $instance_hostname\n";
	    print "My public hostname  : $public_hostname\n";

            $dnsAnswer =  `host $public_hostname $EXTERNAL_DNS_SERVER`;
	    chomp($dnsAnswer);
	    ($junk,$dnsreply) = split(/has\saddress\s+/,$dnsAnswer);
	    print "My public IP        : $dnsreply\n";

	    $privateIPAnswer = `/usr/bin/host $sh_hostname`;
	    chomp($privateIPAnswer);
	    ($junk,$privateIP) = split(/has address\s+/,$privateIPAnswer);


	    print "---- System Changes to be made ... ---\n";
	    print "[1] Adding the following to /etc/hosts on this node:\n";
	    print "\t $dnsreply\t\t$sh_public_hostname $public_hostname\n";
            print "\t $privateIP\t\t$sh_hostname $hostname\n";

	    open(FH,">/etc/hosts") or die "can't open write to /etc/hosts";
	    print FH "## Modified by utility script \n";
	      print FH "127.0.0.1 localhost localhost.localdomain\n"; 
	      print FH "$dnsreply\t\t$public_hostname $sh_public_hostname\n";
	      print FH "$privateIP\t\t$hostname $sh_hostname\n";
	    close(FH);

	    print "\n[2] Will change hostname of this node to $public_hostname\n\n";
	    `echo $sh_hostname > /etc/sysconfig/original_hostname`;
	    `/bin/hostname $public_hostname`;

	    print "\n[3] Write our public IP address to /etc/sysconfig/EC2-public-IPaddr (GridFTP)\n\n";
	    `echo $dnsreply > /etc/sysconfig/EC2-public-IPaddr`;

	    
	}

    }
}