Moved openssh to a recommends & validate existence in plugin startup

dependencies.yaml

@@ -86,7 +86,6 @@ devel_requires:
 main_requires:
   '%assetpack_requires':
   git-core:
-  openssh-common:  # for Build Service Authentication
   hostname:  # for script/configure-web-proxy
   bsdtar:  # for extraction feature of OpenQA::Downloader
   perl(aliased):

dist/rpm/openQA.spec

@@ -199,6 +199,8 @@ Recommends:     qemu
 Recommends:     rsync
 # Optionally enabled with USE_PNGQUANT=1
 Recommends:     pngquant
+# for Build Service Authentication
+Recommends:     openssh-common
 %if 0%{?suse_version} >= 1330
 Requires(pre):  group(nogroup)
 %endif

lib/OpenQA/WebAPI/Plugin/ObsRsync.pm

@@ -8,7 +8,7 @@ use Mojo::File;
 use Mojo::URL;
 use Mojo::UserAgent;
 use POSIX 'strftime';
-
+use File::Which qw(which);
 use OpenQA::Log qw(log_error);
 
 my $dirty_status_filename = '.dirty_status';
@@ -40,6 +40,9 @@ sub register {
     my $plugin_r = $app->routes->find('ensure_operator');
     my $plugin_api_r = $app->routes->find('api_ensure_operator');
 
+    # ssh-keygen is needed for the Build Service authentication.
+    die("ssh-keygen is not availabe. Aborting.\n") unless which('ssh-keygen');
+
     if (!$plugin_r) {
         $app->log->error('Routes not configured, plugin ObsRsync will be disabled') unless $plugin_r;
     }