* $HYDRA_DATA environment variable.

src/Hydra/lib/Hydra.pm

@@ -2,6 +2,7 @@ package Hydra;
 
 use strict;
 use warnings;
+use Hydra::Helper::Nix;
 
 use Catalyst::Runtime '5.70';
 
@@ -20,7 +21,10 @@ our $VERSION = '0.01';
 
 __PACKAGE__->config(
     name => 'Hydra',
-    default_view => "TT"
+    default_view => "TT",
+    session => {
+        storage => getHydraPath . "/session_data"
+    }
 );
 
 __PACKAGE__->setup();

src/Hydra/lib/Hydra/Controller/Root.pm

@@ -751,7 +751,7 @@ sub closure :Local {
 
     return error($c, "Product is not a Nix build.") if $product->type ne "nix-build";
 
-    return error($c, "Path " . $product->path . " is no longer available.") unless Hydra::Helper::Nix::isValidPath($product->path);
+    return error($c, "Path " . $product->path . " is no longer available.") unless isValidPath($product->path);
 
     $c->stash->{current_view} = 'Hydra::View::NixClosure';
     $c->stash->{storePath} = $product->path;

src/Hydra/lib/Hydra/Helper/Nix.pm

@@ -1,14 +1,39 @@
 package Hydra::Helper::Nix;
 
 use strict;
+use Exporter;
+
+our @ISA = qw(Exporter);
+our @EXPORT = qw(isValidPath getHydraPath getHydraDBPath openHydraDB);
 
 
 sub isValidPath {
     my $path = shift;
     $SIG{CHLD} = 'DEFAULT'; # !!! work around system() failing if SIGCHLD is ignored
-    return system("nix-store --check-validity $path") == 0;
+    return system("nix-store --check-validity $path 2> /dev/null") == 0;
+}
+
+
+sub getHydraPath {
+    my $dir = $ENV{HYDRA_DATA};
+    die "The HYDRA_DATA environment variable is not set!\n" unless defined $dir;
+    die "The HYDRA_DATA directory does not exist!\n" unless -d $dir;
+    return $dir;
+}
+
+
+sub getHydraDBPath {
+    my $path = getHydraPath . '/hydra.sqlite';
+    die "The Hydra database ($path) not exist!\n" unless -f $path;
+    return "dbi:SQLite:$path";
+}
+
+
+sub openHydraDB {
+    my $db = Hydra::Schema->connect(getHydraDBPath, "", "", {});
+    $db->storage->dbh->do("PRAGMA synchronous = OFF;");
+    return $db;
 }
 
 
 1;
-

src/Hydra/lib/Hydra/Model/DB.pm

@@ -2,13 +2,11 @@ package Hydra::Model::DB;
 
 use strict;
 use base 'Catalyst::Model::DBIC::Schema';
+use Hydra::Helper::Nix;
 
 __PACKAGE__->config(
     schema_class => 'Hydra::Schema',
-    connect_info => [
+    connect_info => [getHydraDBPath],
-        'dbi:SQLite:../hydra.sqlite',
-        
-    ],
 );
 
 =head1 NAME

src/Hydra/programs/Build.pl

@@ -4,17 +4,10 @@ use strict;
 use File::Basename;
 use File::stat;
 use Hydra::Schema;
+use Hydra::Helper::Nix;
 
 
-my $db = Hydra::Schema->connect("dbi:SQLite:dbname=hydra.sqlite", "", "", {});
+my $db = openHydraDB;
-
-$db->storage->dbh->do("PRAGMA synchronous = OFF;");
-
-
-sub isValidPath {
-    my $path = shift;
-    return system("nix-store --check-validity $path 2> /dev/null") == 0;
-}
 
 
 sub doBuild {

src/Hydra/programs/Runner.pl

@@ -2,13 +2,17 @@
 
 use strict;
 use Cwd;
+use File::Basename;
 use POSIX qw(dup2);
 use Hydra::Schema;
+use Hydra::Helper::Nix;
 
 
-my $db = Hydra::Schema->connect("dbi:SQLite:dbname=hydra.sqlite", "", "", {});
+chdir getHydraPath or die;
+my $db = openHydraDB;
 
-$db->storage->dbh->do("PRAGMA synchronous = OFF;");
+my $hydraHome = $ENV{"HYDRA_HOME"};
+die "The HYDRA_HOME environment variable is not set!\n" unless defined $hydraHome;
 
 
 sub unlockDeadBuilds {
@@ -69,6 +73,7 @@ sub checkBuilds {
 
             foreach my $build (@builds) {
                 my $logfile = getcwd . "/logs/" . $build->id;
+                mkdir(dirname $logfile);
                 unlink($logfile);
                 $build->schedulingInfo->busy(1);
                 $build->schedulingInfo->locker($$);
@@ -91,12 +96,13 @@ sub checkBuilds {
             my $child = fork();
             die unless defined $child;
             if ($child == 0) {
-                open LOG, ">$logfile" or die;
+                eval {
+                    open LOG, ">$logfile" or die "cannot create logfile $logfile";
                     POSIX::dup2(fileno(LOG), 1) or die;
                     POSIX::dup2(fileno(LOG), 2) or die;
-                exec("perl", "-IHydra/lib", "-w",
+                    exec("perl", "-I$hydraHome/lib", "-w", "$ENV{'HYDRA_HOME'}/programs/Build.pl", $id);
-                     "./Hydra/programs/Build.pl", $id);
+                };
-                warn "cannot start build " . $id;
+                warn "cannot start build $id: $@";
                 POSIX::_exit(1);
             }
         };

src/Hydra/programs/Scheduler.pl

@@ -3,19 +3,12 @@
 use strict;
 use XML::Simple;
 use Hydra::Schema;
+use Hydra::Helper::Nix;
 use IPC::Run;
 use POSIX qw(strftime);
 
 
-my $db = Hydra::Schema->connect("dbi:SQLite:dbname=hydra.sqlite", "", "", {});
+my $db = openHydraDB;
-
-$db->storage->dbh->do("PRAGMA synchronous = OFF;");
-
-
-sub isValidPath {
-    my $path = shift;
-    return system("nix-store --check-validity $path 2> /dev/null") == 0;
-}
 
 
 sub captureStdoutStderr {

src/Hydra/root/product-list.tt

@@ -26,7 +26,13 @@
           <pre>$ curl [% c.uri_for('/closure' build.id product.productnr) %] | gunzip | nix-store --import</pre>
 
           <p>The package can then be found in the path <tt>[%
-          product.path %]</tt>.  If you get the error message “imported
+          product.path %]</tt>.  You’ll probably also want to do
+
+          <pre>nix-env -i [% product.path %]</pre>
+
+          to actually install the package in your Nix user environment.</p>
+
+          <p>If you get the error message “imported
           archive lacks a signature”, you should make sure that you have
           sufficient access rights to the Nix store, e.g., run the
           command as <tt>root</tt>.</p>