Add support for self config source (#5459)

Motivation:

This pull request adds support for SELF config source types. This
feature allows the control plane to delegate the decision of which
protocol to use to the client.
Reference:
https://github.com/envoyproxy/envoy/blob/bd18d0fa7790a7e5fe1a95f6ae271ca02614e36c/api/envoy/config/core/v3/config_source.proto#L239

Note that this implementation may not have been completed from envoy
side, so we should use this option with caution.
ref: envoyproxy/envoy#13951

Modifications:

- The dependency relationship between `ResourceNode` and `ConfigSource`
has changed. This can be a problem because the configSource specified in
`ResourceNode#ConfigSource` can be different from the actual
`ConfigSource` used for subscribing. Modified so that `ConfigSource` is
computed before creating a `ResourceNode`.
- Renamed `BootstrapApiConfigs` to `ConfigSourceMapper` since it better
represents the functionality of the class.
- Added `parentConfigSource` to the logic of computing a new
configSource.
- Modified so that subscribed `ResourceNode#configSource` is always
non-null. The only case where this is `null` is for static clusters
(bootstrap clusters)


Result:

- SELF type configSource is now supported

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xds/src/main/java/com/linecorp/armeria/xds/AbstractResourceNode.java

@@ -125,4 +125,8 @@ public XdsType type() {
     public String name() {
         return resourceName;
     }
+
+    ConfigSourceMapper configSourceMapper() {
+        return xdsBootstrap.configSourceMapper().withParentConfigSource(configSource);
+    }
 }

xds/src/main/java/com/linecorp/armeria/xds/ClusterResourceNode.java

@@ -77,11 +77,11 @@ public void doOnChanged(ClusterXdsResource resource) {
         } else if (cluster.hasEdsClusterConfig()) {
             final EdsClusterConfig edsClusterConfig = cluster.getEdsClusterConfig();
             final String serviceName = edsClusterConfig.getServiceName();
-            final ConfigSource configSource = edsClusterConfig.getEdsConfig();
+            final String clusterName = !isNullOrEmpty(serviceName) ? serviceName : cluster.getName();
+            final ConfigSource configSource = configSourceMapper()
+                    .edsConfigSource(cluster.getEdsClusterConfig().getEdsConfig(), clusterName);
             final EndpointResourceNode node =
-                    new EndpointResourceNode(configSource, !isNullOrEmpty(serviceName) ? serviceName
-                                                                                       : cluster.getName(),
-                                             xdsBootstrap(), resource,
+                    new EndpointResourceNode(configSource, clusterName, xdsBootstrap(), resource,
                                              snapshotWatcher, ResourceNodeType.DYNAMIC);
             children().add(node);
             xdsBootstrap().subscribe(node);

xds/src/main/java/com/linecorp/armeria/xds/ClusterRoot.java

@@ -21,6 +21,7 @@
 import com.linecorp.armeria.common.annotation.UnstableApi;
 
 import io.envoyproxy.envoy.config.cluster.v3.Cluster;
+import io.envoyproxy.envoy.config.core.v3.ConfigSource;
 
 /**
  * A root node representing a {@link Cluster}.
@@ -32,13 +33,14 @@ public final class ClusterRoot extends AbstractRoot<ClusterSnapshot> {
 
     private final ClusterResourceNode node;
 
-    ClusterRoot(XdsBootstrapImpl xdsBootstrap, String resourceName) {
+    ClusterRoot(XdsBootstrapImpl xdsBootstrap, ConfigSourceMapper configSourceMapper, String resourceName) {
         super(xdsBootstrap.eventLoop());
         final Cluster cluster = xdsBootstrap.bootstrapClusters().cluster(resourceName);
         if (cluster != null) {
             node = staticCluster(xdsBootstrap, resourceName, this, cluster);
         } else {
-            node = new ClusterResourceNode(null, resourceName, xdsBootstrap,
+            final ConfigSource configSource = configSourceMapper.cdsConfigSource(null, resourceName);
+            node = new ClusterResourceNode(configSource, resourceName, xdsBootstrap,
                                            null, this, ResourceNodeType.DYNAMIC);
             xdsBootstrap.subscribe(node);
         }

xds/src/main/java/com/linecorp/armeria/xds/BootstrapApiConfigs.java → xds/src/main/java/com/linecorp/armeria/xds/ConfigSourceMapper.java

@@ -22,17 +22,25 @@
 import io.envoyproxy.envoy.config.bootstrap.v3.Bootstrap.DynamicResources;
 import io.envoyproxy.envoy.config.core.v3.ConfigSource;
 
-final class BootstrapApiConfigs {
+final class ConfigSourceMapper {
 
+    private final Bootstrap bootstrap;
     @Nullable
     private final ConfigSource bootstrapCdsConfig;
     @Nullable
     private final ConfigSource bootstrapLdsConfig;
     @Nullable
     private final ConfigSource bootstrapAdsConfig;
+    @Nullable
+    private ConfigSource parentConfigSource;
+
+    ConfigSourceMapper(Bootstrap bootstrap) {
+        this(bootstrap, null);
+    }
 
-    BootstrapApiConfigs(Bootstrap bootstrap) {
-        if (bootstrap.hasDynamicResources()) {
+    ConfigSourceMapper(Bootstrap bootstrap, @Nullable ConfigSource parentConfigSource) {
+        this.bootstrap = bootstrap;
+        if (this.bootstrap.hasDynamicResources()) {
             final DynamicResources dynamicResources = bootstrap.getDynamicResources();
             bootstrapCdsConfig = dynamicResources.getCdsConfig();
             if (dynamicResources.hasAdsConfig()) {
@@ -48,39 +56,39 @@ final class BootstrapApiConfigs {
             bootstrapLdsConfig = null;
             bootstrapAdsConfig = null;
         }
+        this.parentConfigSource = parentConfigSource;
     }
 
-    ConfigSource configSource(XdsType type, String resourceName, ResourceNode<?> node) {
-        if (type == XdsType.LISTENER) {
-            return ldsConfigSource(node);
-        } else if (type == XdsType.ROUTE) {
-            return rdsConfigSource(node, resourceName);
-        } else if (type == XdsType.CLUSTER) {
-            return cdsConfigSource(node, resourceName);
-        } else {
-            assert type == XdsType.ENDPOINT;
-            return edsConfigSource(node, resourceName);
-        }
+    ConfigSourceMapper withParentConfigSource(@Nullable ConfigSource parentConfigSource) {
+        return new ConfigSourceMapper(bootstrap, parentConfigSource);
     }
 
-    ConfigSource edsConfigSource(ResourceNode<?> node, String resourceName) {
-        final ConfigSource configSource = node.configSource();
-        if (configSource != null && configSource.hasApiConfigSource()) {
-            return configSource;
+    ConfigSource edsConfigSource(@Nullable ConfigSource configSource, String resourceName) {
+        if (configSource != null) {
+            if (configSource.hasApiConfigSource()) {
+                return configSource;
+            }
+            if (configSource.hasSelf() && parentConfigSource != null) {
+                return parentConfigSource;
+            }
         }
         if (bootstrapAdsConfig != null) {
             return bootstrapAdsConfig;
         }
         throw new IllegalArgumentException("Cannot find an EDS config source for " + resourceName);
     }
 
-    ConfigSource cdsConfigSource(ResourceNode<?> node, String resourceName) {
-        final ConfigSource configSource = node.configSource();
-        if (configSource != null && configSource.hasApiConfigSource()) {
-            return configSource;
-        }
-        if (configSource != null && configSource.hasAds() && bootstrapAdsConfig != null) {
-            return bootstrapAdsConfig;
+    ConfigSource cdsConfigSource(@Nullable ConfigSource configSource, String resourceName) {
+        if (configSource != null) {
+            if (configSource.hasApiConfigSource()) {
+                return configSource;
+            }
+            if (configSource.hasSelf() && parentConfigSource != null) {
+                return parentConfigSource;
+            }
+            if (configSource.hasAds() && bootstrapAdsConfig != null) {
+                return bootstrapAdsConfig;
+            }
         }
         if (bootstrapCdsConfig != null && bootstrapCdsConfig.hasApiConfigSource()) {
             return bootstrapCdsConfig;
@@ -91,31 +99,39 @@ ConfigSource cdsConfigSource(ResourceNode<?> node, String resourceName) {
         throw new IllegalArgumentException("Cannot find a CDS config source for route: " + resourceName);
     }
 
-    ConfigSource rdsConfigSource(ResourceNode<?> node, String resourceName) {
-        final ConfigSource configSource = node.configSource();
-        if (configSource != null && configSource.hasApiConfigSource()) {
-            return configSource;
+    ConfigSource rdsConfigSource(@Nullable ConfigSource configSource, String resourceName) {
+        if (configSource != null) {
+            if (configSource.hasApiConfigSource()) {
+                return configSource;
+            }
+            if (configSource.hasSelf() && parentConfigSource != null) {
+                return parentConfigSource;
+            }
         }
         if (bootstrapAdsConfig != null) {
             return bootstrapAdsConfig;
         }
         throw new IllegalArgumentException("Cannot find an RDS config source for route: " + resourceName);
     }
 
-    ConfigSource ldsConfigSource(ResourceNode<?> node) {
-        final ConfigSource configSource = node.configSource();
-        if (configSource != null && configSource.hasApiConfigSource()) {
-            return configSource;
-        }
-        if (configSource != null && configSource.hasAds() && bootstrapAdsConfig != null) {
-            return bootstrapAdsConfig;
+    ConfigSource ldsConfigSource(@Nullable ConfigSource configSource, String resourceName) {
+        if (configSource != null) {
+            if (configSource.hasApiConfigSource()) {
+                return configSource;
+            }
+            if (configSource.hasSelf() && parentConfigSource != null) {
+                return parentConfigSource;
+            }
+            if (configSource.hasAds() && bootstrapAdsConfig != null) {
+                return bootstrapAdsConfig;
+            }
         }
         if (bootstrapLdsConfig != null && bootstrapLdsConfig.hasApiConfigSource()) {
             return bootstrapLdsConfig;
         }
         if (bootstrapAdsConfig != null) {
             return bootstrapAdsConfig;
         }
-        throw new IllegalArgumentException("Cannot find an LDS config source");
+        throw new IllegalArgumentException("Cannot find an LDS config source for listener: " + resourceName);
     }
 }

xds/src/main/java/com/linecorp/armeria/xds/ListenerResourceNode.java

@@ -54,7 +54,8 @@ public void doOnChanged(ListenerXdsResource resource) {
             if (connectionManager.hasRds()) {
                 final Rds rds = connectionManager.getRds();
                 final String routeName = rds.getRouteConfigName();
-                final ConfigSource configSource = rds.getConfigSource();
+                final ConfigSource configSource = configSourceMapper()
+                        .rdsConfigSource(rds.getConfigSource(), routeName);
                 final RouteResourceNode routeResourceNode =
                         new RouteResourceNode(configSource, routeName, xdsBootstrap(), resource,
                                               snapshotWatcher, ResourceNodeType.DYNAMIC);

xds/src/main/java/com/linecorp/armeria/xds/ListenerRoot.java

@@ -18,6 +18,7 @@
 
 import com.linecorp.armeria.common.annotation.UnstableApi;
 
+import io.envoyproxy.envoy.config.core.v3.ConfigSource;
 import io.envoyproxy.envoy.config.listener.v3.Listener;
 
 /**
@@ -30,14 +31,17 @@ public final class ListenerRoot extends AbstractRoot<ListenerSnapshot> {
 
     private final ListenerResourceNode node;
 
-    ListenerRoot(XdsBootstrapImpl xdsBootstrap, String resourceName, BootstrapListeners bootstrapListeners) {
+    ListenerRoot(XdsBootstrapImpl xdsBootstrap, ConfigSourceMapper configSourceMapper,
+                 String resourceName, BootstrapListeners bootstrapListeners) {
         super(xdsBootstrap.eventLoop());
         final ListenerXdsResource listenerXdsResource = bootstrapListeners.staticListeners().get(resourceName);
         if (listenerXdsResource != null) {
             node = new ListenerResourceNode(null, resourceName, xdsBootstrap, this, ResourceNodeType.STATIC);
             node.onChanged(listenerXdsResource);
         } else {
-            node = new ListenerResourceNode(null, resourceName, xdsBootstrap, this, ResourceNodeType.DYNAMIC);
+            final ConfigSource configSource = configSourceMapper.ldsConfigSource(null, resourceName);
+            node = new ListenerResourceNode(configSource, resourceName, xdsBootstrap,
+                                            this, ResourceNodeType.DYNAMIC);
             xdsBootstrap.subscribe(node);
         }
     }

xds/src/main/java/com/linecorp/armeria/xds/RouteResourceNode.java

@@ -80,7 +80,9 @@ public void doOnChanged(RouteXdsResource resource) {
                                          route, index++, cluster);
                     children().add(node);
                 } else {
-                    node = new ClusterResourceNode(null, clusterName, xdsBootstrap(),
+                    final ConfigSource configSource =
+                            configSourceMapper().cdsConfigSource(null, clusterName);
+                    node = new ClusterResourceNode(configSource, clusterName, xdsBootstrap(),
                                                    resource, snapshotWatcher, virtualHost, route,
                                                    index++, ResourceNodeType.DYNAMIC);
                     children().add(node);

xds/src/main/java/com/linecorp/armeria/xds/XdsBootstrapImpl.java

@@ -16,6 +16,7 @@
 
 package com.linecorp.armeria.xds;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
 import static java.util.Objects.requireNonNull;
 
@@ -38,8 +39,8 @@ final class XdsBootstrapImpl implements XdsBootstrap {
 
     private final Map<ConfigSource, ConfigSourceClient> clientMap = new HashMap<>();
 
-    private final BootstrapApiConfigs bootstrapApiConfigs;
     private final BootstrapListeners bootstrapListeners;
+    private final ConfigSourceMapper configSourceMapper;
     private final BootstrapClusters bootstrapClusters;
     private final Consumer<GrpcClientBuilder> configClientCustomizer;
     private final Node bootstrapNode;
@@ -58,7 +59,7 @@ final class XdsBootstrapImpl implements XdsBootstrap {
                      Consumer<GrpcClientBuilder> configClientCustomizer) {
         this.eventLoop = requireNonNull(eventLoop, "eventLoop");
         this.configClientCustomizer = configClientCustomizer;
-        bootstrapApiConfigs = new BootstrapApiConfigs(bootstrap);
+        configSourceMapper = new ConfigSourceMapper(bootstrap);
         bootstrapListeners = new BootstrapListeners(bootstrap);
         bootstrapClusters = new BootstrapClusters(bootstrap, this);
         bootstrapNode = bootstrap.hasNode() ? bootstrap.getNode() : Node.getDefaultInstance();
@@ -71,9 +72,9 @@ BootstrapClusters bootstrapClusters() {
     void subscribe(ResourceNode<?> node) {
         final XdsType type = node.type();
         final String name = node.name();
-        final ConfigSource mappedConfigSource =
-                bootstrapApiConfigs.configSource(type, name, node);
-        subscribe0(mappedConfigSource, type, name, node);
+        final ConfigSource configSource = node.configSource();
+        checkArgument(configSource != null, "Cannot subscribe to a node without a configSource");
+        subscribe0(configSource, type, name, node);
     }
 
     private void subscribe0(ConfigSource configSource, XdsType type, String resourceName,
@@ -98,25 +99,23 @@ void unsubscribe(ResourceNode<?> node) {
         checkState(!closed, "Attempting to unsubscribe to a closed XdsBootstrap");
         final XdsType type = node.type();
         final String resourceName = node.name();
-        final ConfigSource mappedConfigSource =
-                bootstrapApiConfigs.configSource(type, resourceName, node);
-        final ConfigSourceClient client = clientMap.get(mappedConfigSource);
+        final ConfigSourceClient client = clientMap.get(node.configSource());
         if (client != null && client.removeSubscriber(type, resourceName, node)) {
             client.close();
-            clientMap.remove(mappedConfigSource);
+            clientMap.remove(node.configSource());
         }
     }
 
     @Override
     public ListenerRoot listenerRoot(String resourceName) {
         requireNonNull(resourceName, "resourceName");
-        return new ListenerRoot(this, resourceName, bootstrapListeners);
+        return new ListenerRoot(this, configSourceMapper, resourceName, bootstrapListeners);
     }
 
     @Override
     public ClusterRoot clusterRoot(String resourceName) {
         requireNonNull(resourceName, "resourceName");
-        return new ClusterRoot(this, resourceName);
+        return new ClusterRoot(this, configSourceMapper, resourceName);
     }
 
     @Override
@@ -139,4 +138,8 @@ Map<ConfigSource, ConfigSourceClient> clientMap() {
     public EventExecutor eventLoop() {
         return eventLoop;
     }
+
+    ConfigSourceMapper configSourceMapper() {
+        return configSourceMapper;
+    }
 }

xds/src/main/java/com/linecorp/armeria/xds/XdsConverterUtil.java

@@ -32,8 +32,9 @@ static void validateConfigSource(@Nullable ConfigSource configSource) {
         if (configSource == null || configSource.equals(ConfigSource.getDefaultInstance())) {
             return;
         }
-        checkArgument(configSource.hasAds() || configSource.hasApiConfigSource(),
-                      "Only configSource with Ads or ApiConfigSource is supported for %s", configSource);
+        checkArgument(configSource.hasAds() || configSource.hasApiConfigSource() || configSource.hasSelf(),
+                      "Only one of (Ads, ApiConfigSource, or Self) type ConfigSource is supported for %s",
+                      configSource);
         if (configSource.hasApiConfigSource()) {
             final ApiConfigSource apiConfigSource = configSource.getApiConfigSource();
             final ApiType apiType = apiConfigSource.getApiType();