* Always print hook output on stderr, even if --no-build-output is

  set.
* In the build hook, print a trace message to allow Hydra to pick up
  the name of the remote machine used for the build.

1 files changed, 5 insertions, 2 deletions

diff --git a/scripts/build-remote.pl.in b/scripts/build-remote.pl.in
index 8e3da2553fd8..65c9009b3fe8 100755
--- a/scripts/build-remote.pl.in
+++ b/scripts/build-remote.pl.in
@@ -42,7 +42,7 @@ sub all { $_ || return 0 for @_; 1 }
 # Initialisation.
 my $loadIncreased = 0;
 
-my ($localSystem, $maxSilentTime) = @ARGV;
+my ($localSystem, $maxSilentTime, $printBuildTrace) = @ARGV;
 $maxSilentTime = 0 unless defined $maxSilentTime;
 
 my $currentLoad = $ENV{"NIX_CURRENT_LOAD"};
@@ -197,12 +197,15 @@ REQ: while (1) {
 
 
 # Tell Nix we've accepted the build.
-print STDERR "building `$drvPath' on `$hostName'\n";
 sendReply "accept";
 my @inputs = split /\s/, readline(STDIN);
 my @outputs = split /\s/, readline(STDIN);
 
 
+print STDERR "building `$drvPath' on `$hostName'\n";
+print STDERR "@ build-remote $drvPath $hostName\n" if $printBuildTrace;
+
+
 my $maybeSign = "";
 $maybeSign = "--sign" if -e "/nix/etc/nix/signing-key.sec";