Merge pull request #10161 from Icinga/authBYhost-10157

ApiListener::UpdateObjectAuthority(): distribute auth. by object's host

doc/19-technical-concepts.md

@@ -633,15 +633,12 @@ The algorithm works like this:
     * Set the authority (true or false)
 
 The object authority calculation works "offline" without any message exchange.
-Each instance alculates the SDBM hash of the config object name, puts that in contrast
-modulo the connected endpoints size.
-This index is used to lookup the corresponding endpoint in the connected endpoints array,
-including the local endpoint. Whether the local endpoint is equal to the selected endpoint,
-or not, this sets the authority to `true` or `false`.
-
-```cpp
-authority = endpoints[Utility::SDBM(object->GetName()) % endpoints.size()] == my_endpoint;
-```
+Each instance calculates the SDBM hash of the config object name. However, for objects bound to some
+host, i.e. the object name is composed of `<host_name>!<object_name>`, the SDBM hash is calculated based
+on the host name only instead of the full object name. That way, each child object like services, downtimes,
+etc. will be assigned to the same endpoint as the host object itself. The resulting hash modulo (`%`) the number of
+connected endpoints produces the index of the endpoint which is authoritative for this config object. If the
+endpoint at this index is equal to the local endpoint, the authority is set to `true`, otherwise it is set to `false`.
 
 `ConfigObject::SetAuthority(bool authority)` triggers the following events:
 

lib/remote/apilistener-authority.cpp

@@ -25,6 +25,7 @@ void ApiListener::UpdateObjectAuthority()
 
 	std::vector<Endpoint::Ptr> endpoints;
 	Endpoint::Ptr my_endpoint;
+	int hostChildrenInheritObjectAuthority = 0;
 
 	if (my_zone) {
 		my_endpoint = Endpoint::GetLocalEndpoint();
@@ -38,6 +39,10 @@ void ApiListener::UpdateObjectAuthority()
 				continue;
 
 			endpoints.push_back(endpoint);
+
+			if (endpoint == my_endpoint || endpoint->GetCapabilities() & static_cast<uint_fast64_t>(ApiCapabilities::HostChildrenInheritObjectAuthority)) {
+				++hostChildrenInheritObjectAuthority;
+			}
 		}
 
 		double startTime = Application::GetStartTime();
@@ -65,10 +70,24 @@ void ApiListener::UpdateObjectAuthority()
 
 			bool authority;
 
-			if (!my_zone)
+			if (my_zone) {
+				auto name (object->GetName());
+
+				// If all endpoints know this algorithm, we can use it.
+				if (hostChildrenInheritObjectAuthority == endpoints.size()) {
+					auto exclamation (name.FindFirstOf('!'));
+
+					// Pin child objects of hosts (HOST!...) to the same endpoint as the host.
+					// This reduces cross-object action latency withing the same host.
+					if (exclamation != String::NPos) {
+						name.erase(name.Begin() + exclamation, name.End());
+					}
+				}
+
+				authority = endpoints[Utility::SDBM(name) % endpoints.size()] == my_endpoint;
+			} else {
 				authority = true;
-			else
-				authority = endpoints[Utility::SDBM(object->GetName()) % endpoints.size()] == my_endpoint;
+			}
 
 #ifdef I2_DEBUG
 // 			//Enable on demand, causes heavy logging on each run.

lib/remote/apilistener.cpp

@@ -640,10 +640,6 @@ static const auto l_AppVersionInt (([]() -> unsigned long {
 		+ boost::lexical_cast<unsigned long>(match[3].str());
 })());
 
-static const auto l_MyCapabilities (
-	(uint_fast64_t)ApiCapabilities::ExecuteArbitraryCommand | (uint_fast64_t)ApiCapabilities::IfwApiCheckCommand
-);
-
 /**
  * Processes a new client connection.
  *
@@ -774,7 +770,7 @@ void ApiListener::NewClientHandlerInternal(
 				{ "method", "icinga::Hello" },
 				{ "params", new Dictionary({
 					{ "version", (double)l_AppVersionInt },
-					{ "capabilities", (double)l_MyCapabilities }
+					{ "capabilities", (double)ApiCapabilities::MyCapabilities }
 				}) }
 			}), yc);
 
@@ -813,7 +809,7 @@ void ApiListener::NewClientHandlerInternal(
 					{ "method", "icinga::Hello" },
 					{ "params", new Dictionary({
 						{ "version", (double)l_AppVersionInt },
-						{ "capabilities", (double)l_MyCapabilities }
+						{ "capabilities", (double)ApiCapabilities::MyCapabilities }
 					}) }
 				}), yc);
 
@@ -1801,6 +1797,10 @@ Value ApiListener::HelloAPIHandler(const MessageOrigin::Ptr& origin, const Dicti
 				endpoint->SetIcingaVersion(nodeVersion);
 				endpoint->SetCapabilities((double)params->Get("capabilities"));
 
+				if (endpoint->GetZone() == Zone::GetLocalZone()) {
+					UpdateObjectAuthority();
+				}
+
 				if (nodeVersion == 0u) {
 					nodeVersion = 21200;
 				}

lib/remote/apilistener.hpp

@@ -70,6 +70,9 @@ enum class ApiCapabilities : uint_fast64_t
 {
 	ExecuteArbitraryCommand = 1u << 0u,
 	IfwApiCheckCommand = 1u << 1u,
+	HostChildrenInheritObjectAuthority = 1u << 2u,
+
+	MyCapabilities = ExecuteArbitraryCommand | IfwApiCheckCommand | HostChildrenInheritObjectAuthority
 };
 
 /**