Metrics docs for sara

docs/source/maintenance/index.rst

@@ -13,3 +13,4 @@ Hardware requirements, deployment process in details, aspects related to securit
     sec-install.rst
     shepherd.rst
     troubleshooting.rst
+    metrics.rst

docs/source/maintenance/metrics.rst

@@ -0,0 +1,41 @@
+=======
+Metrics
+=======
+
+To conveniently and thoroughly monitor the performance of the network, you can now use metrics.
+It is numeric data collected over time about your Iroha network.
+You can then analyse the data to make your project even more efficient!
+
+How to use metrics?
+===================
+
+To use metrics, you need to add it to your `Iroha configuration <../configure/index.html#deployment-specific-parameters>`_ and use Iroha version that is newer than 1.2.1.
+
+Then, you can simply use the ip address to access the data from the running Iroha instance.
+
+Here is an example:
+
+.. code-block:: shell
+
+  > curl http://127.0.0.1:8080/metrics
+
+
+will give you results like: 
+
+.. code-block:: shell
+
+  # HELP blocks_height Total number of blocks in chain
+  # TYPE blocks_height gauge
+  blocks_height 135543
+  # HELP peers_number Total number peers to send transactions and request proposals
+  # TYPE peers_number gauge
+  peers_number 7
+  # HELP number_of_domains Total number of domains in WSV
+  # TYPE number_of_domains gauge
+  number_of_domains 14
+  # HELP total_number_of_transactions Total number of transactions in blockchain
+  # TYPE total_number_of_transactions gauge
+  total_number_of_transactions 216499
+  # HELP number_of_signatures_in_last_block Number of signatures in last block
+  # TYPE number_of_signatures_in_last_block gauge
+  number_of_signatures_in_last_block 5