couchdb-trigger.pl

   1 #!/usr/bin/perl
   2
   3 # back-end trigger server for CouchDB monitoring changes feed:
   4 #
   5 # http://wiki.apache.org/couchdb/HTTP_database_API#Changes
   6 #
   7 # implements state machine using document which you cen put with:
   8 #
   9 # curl -X PUT http://localhost:5984/monitor/df -d '{"trigger":{"command":"df -P","format":"table"}}'
  10 #
  11 # DEFAULT TRIGGER EXECUTE SHELL COMMANDS. IT IS NOT SECURE IF YOUR COUCHDB ISN'T SECURE!
  12
  13 use warnings;
  14 use strict;
  15
  16 use lib 'common/mojo/lib';
  17
  18 use Mojo::Client;
  19 use Mojo::JSON;
  20 use Time::HiRes qw(time);
  21
  22 my $url = 'http://localhost:5984/monitor';
  23
  24 sub _trigger {
  25         my $trigger = $_[0]->{trigger};
  26         if ( my $command = $trigger->{command} ) {
  27                 # FIXME SECURITY HOLE
  28                 my $output = $trigger->{output} = `$command`;
  29
  30                 $trigger->{output} =
  31                         [ map { [ split (/\s+/,$_) ] } split(/\n/,$output) ]
  32                         if $trigger->{format} =~ m/table/i;
  33         }
  34         return $trigger;
  35 }
  36
  37 my $seq = 0;
  38
  39 my $client = Mojo::Client->new;
  40 our $json   = Mojo::JSON->new;
  41 sub info { warn $_[0], " ",$json->encode($_[1]),$/ }
  42 sub debug { info "# $_[0]", $_[1] }
  43 my $error;
  44
  45 $client->keep_alive_timeout(90); # couchdb timeout is 60s
  46
  47 while( ! $error ) {
  48
  49         my $changes_feed = "$url/_changes?feed=continuous;include_docs=true;since=$seq";
  50         info 'GET' => $changes_feed;
  51         my $tx = $client->build_tx( GET => $changes_feed );
  52         $tx->res->body(sub{
  53                 my ( $content, $body ) = @_;
  54
  55                 debug 'BODY' => $body;
  56
  57                 if ( length($body) == 0 ) {
  58                         warn "# empty chunk, heartbeat?\n";
  59                         return;
  60                 }
  61
  62                 foreach ( split(/\r?\n/, $body) ) { # we can get multiple documents in one chunk
  63
  64                         my $change = $json->decode($_);
  65
  66                         if ( exists $change->{error} ) {
  67                                 $error = $change;
  68                         } elsif ( exists $change->{last_seq} ) {
  69                                 $seq = $change->{last_seq};
  70                         } elsif ( $change->{seq} <= $seq ) {
  71                                 info "ERROR: stale" => $change;
  72                         } elsif ( exists $change->{changes} ) {
  73
  74                                 my $id  = $change->{id} || warn "no id?";
  75                                 my $rev = $change->{changes}->[0]->{rev} || warn "no rev?";
  76                                    $seq = $change->{seq} || warn "no seq?";
  77
  78                                 debug 'change' => $change;
  79
  80                                 if ( my $trigger = $change->{doc}->{trigger} ) {
  81                                         if ( exists $trigger->{active} ) {
  82                                                 debug 'trigger.active',  $change->{doc}->{trigger}->{active};
  83                                         } else {
  84                                                 $trigger->{active} = [ time() ];
  85
  86                                                 debug 'TRIGGER start PUT ', $change->{doc};
  87                                                 $client->put( "$url/$id" => $json->encode( $change->{doc} ) => sub {
  88                                                         my ($client,$tx) = @_;
  89                                                         if ($tx->error) {
  90                                                                 if ( $tx->res->code == 409 ) {
  91                                                                         info "TRIGGER ABORTED started on another worker? ", $tx->error;
  92                                                                 } else {
  93                                                                         info "ERROR ", $tx->error;
  94                                                                 }
  95                                                         } else {
  96                                                                 my $res = $tx->res->json;
  97                                                                 $change->{doc}->{_rev} = $res->{rev};
  98
  99                                                                 debug "TRIGGER execute ", $change->{doc};
 100                                                                 _trigger( $change->{doc} );
 101
 102                                                                 push @{ $trigger->{active} }, time(), 0; # last timestamp
 103
 104                                                                 $client->put( "$url/$id" => $json->encode( $change->{doc} ) => sub {
 105                                                                         my ($client,$tx) = @_;
 106                                                                         if ($tx->error) {
 107                                                                                 info "ERROR", $tx->error;
 108                                                                         } else {
 109                                                                                 my $res = $tx->res->json;
 110                                                                                 $change->{doc}->{_rev} = $res->{rev};
 111                                                                                 info "TRIGGER finish ", $change->{doc};
 112                                                                         }
 113                                                                 })->process;
 114                                                         }
 115                                                 })->process;
 116                                         }
 117                                 }
 118                         } else {
 119                                 warn "UNKNOWN", $json->encode($change);
 120                         }
 121
 122                 }
 123
 124         });
 125         $client->start($tx);
 126
 127 }
 128
 129 die "ERROR ", $json->encode($error) if $error;