add operator area create support (G-Research#381)

Consul/Interfaces/IOperatorEndpoint.cs

@@ -45,6 +45,8 @@ public interface IOperatorEndpoint
         Task<QueryResult<ConsulLicense>> GetConsulLicense(string datacenter = "", CancellationToken ct = default);
         Task<QueryResult<string[]>> SegmentList(QueryOptions q, CancellationToken cancellationToken = default);
         Task<QueryResult<string[]>> SegmentList(CancellationToken cancellationToken = default);
+        Task<WriteResult<string>> CreateArea(Area area, WriteOptions q, CancellationToken ct = default);
+        Task<WriteResult<string>> CreateArea(Area area, CancellationToken ct = default);
 
     }
 }

Consul/Operator.cs

@@ -100,6 +100,34 @@ public class KeyringResponse
         public int NumNodes { get; set; }
     }
 
+    public class Area
+    {
+        /// <summary>
+        /// ID is this identifier for an area (a UUID). This must be left empty
+        /// when creating a new area.
+        /// </summary>
+        public string ID { get; set; }
+        /// <summary>
+        /// PeerDatacenter is the peer Consul datacenter that will make up the
+        /// other side of this network area. Network areas always involve a pair
+        /// of datacenters: the datacenter where the area was created, and the
+        /// peer datacenter. This is required.
+        /// </summary>
+        public string PeerDatacenter { get; set; }
+
+        /// <summary>
+        /// RetryJoin specifies the address of Consul servers to join to, such as
+	    /// an IPs or hostnames with an optional port number. This is optional.
+        /// </summary>
+        public string[] RetryJoin { get; set; }
+
+        /// <summary>
+        /// UseTLS specifies whether gossip over this area should be encrypted with TLS
+        /// if possible.
+        /// </summary>
+        public bool UseTLS { get; set; }
+    }
+
     public class Operator : IOperatorEndpoint
     {
         private readonly ConsulClient _client;
@@ -249,6 +277,25 @@ public Task<QueryResult<string[]>> SegmentList(CancellationToken ct = default)
         {
             return SegmentList(QueryOptions.Default, ct);
         }
+
+        /// <summary>
+        /// CreateArea will create a new network area. The ID in the given structure must
+        /// be empty and a generated ID will be returned on success.
+        /// </summary>
+        public Task<WriteResult<string>> CreateArea(Area area, CancellationToken ct = default)
+        {
+            return CreateArea(area, WriteOptions.Default, ct);
+        }
+
+        /// <summary>
+        /// CreateArea will create a new network area. The ID in the given structure must
+        /// be empty and a generated ID will be returned on success.
+        /// </summary>
+        public async Task<WriteResult<string>> CreateArea(Area area, WriteOptions q, CancellationToken ct = default)
+        {
+            var res = await _client.Post<Area, Area>("/v1/operator/area", area, q).Execute(ct).ConfigureAwait(false);
+            return new WriteResult<string>(res, res.Response.ID);
+        }
     }
 
     public class ConsulLicense