Provide parallel_one_host_only via workers config file

docs/WritingTests.asciidoc

@@ -672,8 +672,8 @@ eventually workers can be held back for the cluster.
 It is possible to ensure that all jobs within the same _parallel_ cluster are
 executed on the same worker host. This is useful for connecting the SUTs without
 having to connect the physical worker hosts. Use `PARALLEL_ONE_HOST_ONLY=1` to
-enable this. Note that adding this setting in `workers.ini` has currently *no*
-effect.
+enable this. This setting can be applied as a test variable during the time
+of scheduling as well as in the worker configuration file `workers.ini`.
 
 WARNING: You need to provide enough worker slots on single worker hosts to fit
 an entire cluster. So this feature is mainly intended to workaround situations

etc/openqa/workers.ini

@@ -6,6 +6,10 @@
 # space separated list of webuis to connect to (empty defaults to localhost)
 #HOST = http://openqa.example.host
 
+# Enable to restrict any multi-machine jobs taken by this worker host to only run here.
+# Disabled by default.
+#PARALLEL_ONE_HOST_ONLY = 0
+
 # Specify a cache directory for assets and tests to sync them automatically via
 # http/rsync; the specified path is just an example but what you would usually
 # use on a normal setup

lib/OpenQA/WebAPI/Controller/API/V1/Worker.pm

@@ -173,18 +173,17 @@ sub create {
     my ($self) = @_;
     my $validation = $self->validation;
     my @validation_params
-      = qw(cpu_arch cpu_modelname cpu_opmode cpu_flags mem_max isotovideo_interface_version websocket_api_version worker_class);
+      = qw(cpu_arch cpu_modelname cpu_opmode cpu_flags mem_max isotovideo_interface_version websocket_api_version worker_class parallel_one_host_only);
     $validation->required($_) for qw(host instance cpu_arch mem_max worker_class);
-    $validation->optional($_)
-      for qw(cpu_modelname cpu_opmode cpu_flags isotovideo_interface_version job_id websocket_api_version);
+    $validation->optional($_) for qw(cpu_modelname cpu_opmode cpu_flags isotovideo_interface_version job_id
+      websocket_api_version parallel_one_host_only);
     return $self->reply->validation_error({format => 'json'}) if $validation->has_error;
 
     my $host = $validation->param('host');
     my $instance = $validation->param('instance');
     my $job_ids = $validation->every_param('job_id');
     my $caps = {};
     $caps->{$_} = $validation->param($_) for @validation_params;
-
     my $id;
     try {
         $id = $self->_register($self->schema, $host, $instance, $caps, $job_ids);

lib/OpenQA/Worker.pm

@@ -212,7 +212,8 @@ sub capabilities ($self) {
           = join(',', map { 'qemu_' . $_ } @{$supported_archs_by_cpu_archs{$caps->{cpu_arch}} // [$caps->{cpu_arch}]});
         # TODO: check installed qemu and kvm?
     }
-
+    $caps->{parallel_one_host_only} = $global_settings->{PARALLEL_ONE_HOST_ONLY}
+      if exists $global_settings->{PARALLEL_ONE_HOST_ONLY};
     return $self->{_caps} = $caps;
 }
 

t/24-worker-overall.t

@@ -142,6 +142,14 @@ subtest 'capabilities' => sub {
     # clear cached capabilities
     delete $worker->{_caps};
 
+    subtest 'capabilities include PARALLEL_ONE_HOST_ONLY setting if present' => sub {
+        $global_settings->{PARALLEL_ONE_HOST_ONLY} = 1;
+        $capabilities = $worker->capabilities;
+        is $capabilities->{parallel_one_host_only}, 1, 'capabilities contain expected information';
+        delete $global_settings->{PARALLEL_ONE_HOST_ONLY};
+    };
+    delete $worker->{_caps};
+
     subtest 'deduce worker class from CPU architecture' => sub {
         delete $global_settings->{WORKER_CLASS};
         $global_settings->{ARCH} = 'aarch64';