add new sys/step-down api

for hashicorp/vault#1146

src/VaultSharp/IVaultClient.cs

@@ -371,6 +371,17 @@ public interface IVaultClient
         /// </returns>
         Task<Leader> GetLeaderAsync();
 
+        /// <summary>
+        /// Forces the node to give up active status. 
+        /// If the node does not have active status, this endpoint does nothing. 
+        /// Note that the node will sleep for ten seconds before attempting to grab the active lock again, 
+        /// but if no standby nodes grab the active lock in the interim, 
+        /// the same node may become the active node again. 
+        /// This API is a root protected call.
+        /// </summary>
+        /// <returns>The task.</returns>
+        Task StepDownActiveNodeAsync();
+
         /// <summary>
         /// Gets information about the current encryption key used by Vault
         /// </summary>

src/VaultSharp/VaultClient.cs

@@ -366,6 +366,13 @@ public async Task<Leader> GetLeaderAsync()
             return leader;
         }
 
+        public async Task StepDownActiveNodeAsync()
+        {
+            await
+                MakeVaultApiRequest("sys/step-down", HttpMethod.Put)
+                    .ConfigureAwait(_continueAsyncTasksOnCapturedContext);
+        }
+
         public async Task<EncryptionKeyStatus> GetEncryptionKeyStatusAsync()
         {
             var keyStatus = await MakeVaultApiRequest<EncryptionKeyStatus>("sys/key-status", HttpMethod.Get).ConfigureAwait(continueOnCapturedContext: _continueAsyncTasksOnCapturedContext);

test/VaultSharp.UnitTests/End2End/VaultClientEnd2EndTests.cs

@@ -41,6 +41,8 @@ public async Task AllTests()
                 // await GithubAuthenticationProviderTests();
             }
 
+            await _authenticatedClient.StepDownActiveNodeAsync();
+
             await EncryptStrongTests();
             await MountedSecretBackendTests();
             await MountedAuthenticationBackendTests();