[ProcessContainers] Have default container provider

Source/com/Communicator.h

@@ -965,7 +965,7 @@ namespace RPC {
 
                 ContainerConfig()
                     : Core::JSON::Container()
-                    , ContainerType(ProcessContainers::IContainer::LXC)
+                    , ContainerType(ProcessContainers::IContainer::DEFAULT)
 #ifdef __DEBUG__
                     , ContainerPath()
 #endif

Source/extensions/processcontainers/ContainerAdministrator.cpp

@@ -52,17 +52,50 @@ namespace ProcessContainers {
             container.Add(value.Data(), &specific);
             container.FromString(configuration);
 
+            if ((specific.IsSet() == false) && (_producers.size() == 1)) {
+                // Looks like the configuration for this provider is not specified, however there is only one container
+                // system available, so let's forward the entire config (perhaps it's a legacy config file).
+                specific = configuration;
+            }
+
             TRACE(Trace::Information, (_T("Initializing container runtime system '%s'..."), value.Data()));
 
             // Pass the configuration to the runtime
-            const uint32_t initResult = runtime.second->Initialize(specific);
+            const uint32_t initResult = runtime.second->Initialize(specific.Value());
 
             if (initResult != Core::ERROR_NONE) {
                 TRACE(Trace::Error, (_T("Initialization failure")));
                 result = Core::ERROR_GENERAL;
             }
         }
 
+        if (_producers.empty() == true) {
+            SYSLOG(Logging::Error, (_T("No container runtime systems are available!")));
+        }
+        else if (_producers.size() == 1) {
+            // Since there is only one provider available, make it the default one
+            _default = _producers.cbegin()->first;
+        }
+        else {
+            Core::JSON::EnumType<IContainer::containertype> defaultProducer;
+            Core::JSON::Container config;
+            config.Add(_T("default"), &defaultProducer);
+            config.FromString(configuration);
+
+            if (defaultProducer.IsSet() == true) {
+                _default = defaultProducer.Value();
+                ASSERT(_default != IContainer::DEFAULT);
+                ASSERT(_producers.find(_default) != _producers.end());
+
+                const Core::EnumerateType<IContainer::containertype> value(_default);
+                DEBUG_VARIABLE(value);
+                TRACE(Trace::Information, (_T("Default container runtime is '%s'"), value.Data()));
+            }
+            else {
+                TRACE(Trace::Information, (_T("Default container runtime is not set")));
+            }
+        }
+
         _adminLock.Unlock();
 
         return (result);
@@ -86,27 +119,35 @@ namespace ProcessContainers {
 
         _adminLock.Lock();
 
-        auto it = _producers.find(type);
+        const IContainer::containertype containerType = (type == IContainer::DEFAULT? _default : type);
+
+        if (containerType != IContainer::DEFAULT) {
 
-        const Core::EnumerateType<IContainer::containertype> value(type);
-        DEBUG_VARIABLE(value);
+            auto it = _producers.find(containerType);
 
-        ASSERT(value.IsSet() == true);
+            const Core::EnumerateType<IContainer::containertype> value(containerType);
+            DEBUG_VARIABLE(value);
 
-        if (it != _producers.end()) {
+            ASSERT(value.IsSet() == true);
+
+            if (it != _producers.end()) {
 
-            auto& runtime = (*it).second;
-            ASSERT(runtime != nullptr);
+                auto& runtime = (*it).second;
+                ASSERT(runtime != nullptr);
 
-            container = runtime->Container(id, searchPaths, logPath, configuration);
+                container = runtime->Container(id, searchPaths, logPath, configuration);
 
-            if (container.IsValid() == true) {
-               TRACE(Trace::Information, (_T("Container '%s' created successfully (runtime system '%s')"),
-                        container->Id().c_str(), value.Data()));
+                if (container.IsValid() == true) {
+                    TRACE(Trace::Information, (_T("Container '%s' created successfully (runtime system '%s')"),
+                            container->Id().c_str(), value.Data()));
+                }
+            }
+            else {
+                TRACE(Trace::Error, (_T("Container runtime system '%s' is not enabled!"), value.Data()));
             }
         }
         else {
-            TRACE(Trace::Error, (_T("Container runtime system '%s' is not enabled!"), value.Data()));
+            TRACE(Trace::Error, (_T("Container runtime system not specified for '%s'"), id.c_str()));
         }
 
         _adminLock.Unlock();

Source/extensions/processcontainers/ContainerAdministrator.h

@@ -34,6 +34,9 @@ namespace ProcessContainers {
 
         ContainerAdministrator()
             : _adminLock()
+            , _producers()
+            , _containers()
+            , _default(IContainer::DEFAULT)
         {
         }
 
@@ -107,6 +110,7 @@ namespace ProcessContainers {
         mutable Core::CriticalSection _adminLock;
         std::map<IContainer::containertype, IContainerProducer*> _producers;
         Core::ProxyListType<IContainer> _containers;
+        IContainer::containertype _default;
     };
 
 } // namespace ProcessContainers

Source/extensions/processcontainers/IProcessContainers.h

@@ -74,6 +74,7 @@ namespace ProcessContainers {
     struct IContainer {
 
         enum containertype : uint8_t {
+            DEFAULT,
             LXC,
             RUNC,
             CRUN,