* 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.

2 files changed, 17 insertions, 6 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";
 
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 30e37e4e9e92..210486fbc205 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -678,7 +678,9 @@ HookInstance::HookInstance()
                 throw SysError("dupping builder's stdout/stderr");
             
             execl(buildHook.c_str(), buildHook.c_str(), thisSystem.c_str(),
-                (format("%1%") % maxSilentTime).str().c_str(), NULL);
+                (format("%1%") % maxSilentTime).str().c_str(),
+                (format("%1%") % printBuildTrace).str().c_str(),
+                NULL);
             
             throw SysError(format("executing `%1%'") % buildHook);
             
@@ -1362,7 +1364,8 @@ HookReply DerivationGoal::tryBuildHook()
             reply = string(s, 2);
             break;
         }
-        handleChildOutput(worker.hook->fromHook.readSide, s + "\n");
+        s += "\n";
+        writeToStderr((unsigned char *) s.c_str(), s.size());
     }
 
     debug(format("hook reply is `%1%'") % reply);
@@ -2023,11 +2026,16 @@ void DerivationGoal::deleteTmpDir(bool force)
 
 void DerivationGoal::handleChildOutput(int fd, const string & data)
 {
-    if (verbosity >= buildVerbosity)
-        writeToStderr((unsigned char *) data.c_str(), data.size());
     if ((hook && fd == hook->builderOut.readSide) ||
         (!hook && fd == builderOut.readSide))
+    {
+        if (verbosity >= buildVerbosity)
+            writeToStderr((unsigned char *) data.c_str(), data.size());
         writeFull(fdLogFile, (unsigned char *) data.c_str(), data.size());
+    }
+
+    if (hook && fd == hook->fromHook.readSide)
+        writeToStderr((unsigned char *) data.c_str(), data.size());
 }