add support for discovery chain get method (G-Research#355)

Consul/Client.cs

@@ -473,6 +473,7 @@ private void InitializeEndpoints()
             _aclReplication = new Lazy<ACLReplication>(() => new ACLReplication(this));
             _authMethod = new Lazy<AuthMethod>(() => new AuthMethod(this));
             _namespaces = new Lazy<Namespaces>(() => new Namespaces(this));
+            _discoveryChain = new Lazy<DiscoveryChain>(() => new DiscoveryChain(this));
         }
 
         #region IDisposable Support

Consul/DiscoveryChain.cs

@@ -0,0 +1,169 @@
+// -----------------------------------------------------------------------
+//  <copyright file="DiscoveryChain.cs" company="G-Research Limited">
+//    Copyright 2020 G-Research Limited
+//
+//    Licensed under the Apache License, Version 2.0 (the "License"),
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+//  </copyright>
+// -----------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using System.Threading;
+using Consul.Interfaces;
+using Newtonsoft.Json;
+
+namespace Consul
+{
+    public class DiscoveryChainResponse
+    {
+        public CompiledDiscoveryChain Chain { get; set; }
+    }
+
+    public class CompiledDiscoveryChain
+    {
+        public string ServiceName { get; set; }
+        public string Namespace { get; set; }
+        public string Datacenter { get; set; }
+
+        // CustomizationHash is a unique hash of any data that affects the
+        // compilation of the discovery chain other than config entries or the
+        // name/namespace/datacenter evaluation criteria.
+        //
+        // If set, this value should be used to prefix/suffix any generated load
+        // balancer data plane objects to avoid sharing customized and
+        // non-customized versions.
+        public string CustomizationHash { get; set; }
+
+        // Protocol is the overall protocol shared by everything in the chain.
+        public string Protocol { get; set; }
+        // StartNode is the first key into the Nodes map that should be followed
+        // when walking the discovery chain.
+        public string StartNode { get; set; }
+
+        // Nodes contains all nodes available for traversal in the chain keyed by a
+        // unique name.  You can walk this by starting with StartNode.
+        //
+        // NOTE: The names should be treated as opaque values and are only
+        // guaranteed to be consistent within a single compilation.
+        public Dictionary<string, DiscoveryGraphNode> Nodes { get; set; }
+
+        // Targets is a list of all targets used in this chain.
+        // NOTE: The names should be treated as opaque values and are only
+        // guaranteed to be consistent within a single compilation.
+        public Dictionary<string, DiscoveryTarget> Targets { get; set; }
+    }
+
+    public class DiscoveryGraphNode
+    {
+        public string Type { get; set; }
+        public string Name { get; set; } // This is NOT necessarily a service
+
+        // fields for Type==router
+        public List<DiscoveryRoute> Routes { get; set; }
+
+        // fields for Type==splitter
+        public List<DiscoverySplit> Splits { get; set; }
+
+        // fields for Type==resolver
+        public DiscoveryResolver Resolver { get; set; }
+
+        // shared by Type==resolver || Type==splitter
+        public LoadBalancerConfig LoadBalancer { get; set; }
+    }
+
+    public class DiscoverySplit
+    {
+        public float Weight { get; set; }
+        public string NextNode { get; set; }
+    }
+
+    public class DiscoveryRoute
+    {
+        public Routes Definition { get; set; }
+        public string NextNode { get; set; }
+    }
+
+    public class DiscoveryResolver
+    {
+        public bool Default { get; set; }
+
+        [JsonConverter(typeof(DurationTimespanConverter))]
+        public TimeSpan? ConnectTimeout { get; set; }
+
+        public string Target { get; set; }
+        public DiscoveryFailover Failover { get; set; }
+    }
+    public class DiscoveryFailover
+    {
+        public List<string> Targets { get; set; }
+    }
+
+    public class DiscoveryTarget
+    {
+        public string ID { get; set; }
+        public string Service { get; set; }
+        public string ServiceSubset { get; set; }
+        public string Namespace { get; set; }
+        public string Datacenter { get; set; }
+        public MeshGatewayConfig MeshGateway { get; set; }
+        public ServiceResolverEntry Subset { get; set; }
+        public bool External { get; set; }
+        public string SNI { get; set; }
+        public string Name { get; set; }
+    }
+
+    public class DiscoveryChain : IDiscoveryChainEndpoint
+    {
+        private readonly ConsulClient _client;
+
+        internal DiscoveryChain(ConsulClient c)
+        {
+            _client = c;
+        }
+
+        /// <summary>
+        /// Get is used to return the compiled discovery chain for a service.
+        /// </summary>
+        /// <param name="name">Specifies the service to query when compiling the discovery chain</param>
+        /// <param name="q">Query Options</param>
+        /// <param name="ct">Cancellation Token</param>
+        /// <returns>An empty write result</returns>
+        public Task<QueryResult<DiscoveryChainResponse>> Get(string name, QueryOptions q, CancellationToken ct = default)
+        {
+            return _client.Get<DiscoveryChainResponse>($"/v1/discovery-chain/{name}", q).Execute(ct);
+        }
+
+        /// <summary>
+        /// Get is used to return the compiled discovery chain for a service.
+        /// </summary>
+        /// <param name="name">Specifies the service to query when compiling the discovery chain</param>
+        /// <param name="ct">Cancellation Token</param>
+        /// <returns>An empty write result</returns>
+        public Task<QueryResult<DiscoveryChainResponse>> Get(string name, CancellationToken ct = default)
+        {
+            return Get(name, QueryOptions.Default, ct);
+        }
+    }
+
+    public partial class ConsulClient : IConsulClient
+    {
+        private Lazy<DiscoveryChain> _discoveryChain;
+
+        /// <summary>
+        /// DiscoveryChain returns a handle to the discovery chain endpoints
+        /// </summary>
+        public IDiscoveryChainEndpoint DiscoveryChain => _discoveryChain.Value;
+    }
+}

Consul/Interfaces/IConsulClient.cs

@@ -64,5 +64,6 @@ public interface IConsulClient : IDisposable
         IPreparedQueryEndpoint PreparedQuery { get; }
         ICoordinateEndpoint Coordinate { get; }
         ISnapshotEndpoint Snapshot { get; }
+        IDiscoveryChainEndpoint DiscoveryChain { get; }
     }
 }

Consul/Interfaces/IDiscoveryChainEndpoint.cs

@@ -0,0 +1,35 @@
+// -----------------------------------------------------------------------
+//  <copyright file="IDiscoveryChainEndpoint.cs" company="G-Research Limited">
+//    Copyright 2020 G-Research Limited
+//
+//    Licensed under the Apache License, Version 2.0 (the "License"),
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//       http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+//  </copyright>
+// -----------------------------------------------------------------------
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Consul.Interfaces
+{
+    /// <summary>
+    /// The interface for the Discovery Chain API Endpoints
+    /// </summary>
+    public interface IDiscoveryChainEndpoint
+    {
+        Task<QueryResult<DiscoveryChainResponse>> Get(string name, QueryOptions q, CancellationToken ct = default); 
+        Task<QueryResult<DiscoveryChainResponse>> Get(string name, CancellationToken ct = default); 
+    }
+}