Add Arista LANZ consumer input plugin (#4112)

plugins/inputs/lanz/README.md

@@ -0,0 +1,87 @@
+# Arista LANZ Consumer Input Plugin
+
+This plugin provides a consumer for use with Arista Networks’ Latency Analyzer (LANZ)
+
+Metrics are read from a stream of data via TCP through port 50001 on the
+switches management IP. The data is in Protobuffers format. For more information on Arista LANZ
+
+- https://www.arista.com/en/um-eos/eos-latency-analyzer-lanz
+
+This plugin uses Arista's sdk.
+
+- https://github.com/aristanetworks/goarista
+
+### Configuration
+
+You will need to configure LANZ and enable streaming LANZ data.
+
+- https://www.arista.com/en/um-eos/eos-section-44-3-configuring-lanz
+- https://www.arista.com/en/um-eos/eos-section-44-3-configuring-lanz#ww1149292
+
+```toml
+[[inputs.lanz]]
+  servers = [
+    "tcp://switch1.int.example.com:50001",
+    "tcp://switch2.int.example.com:50001",
+  ]
+```
+
+### Metrics
+
+For more details on the metrics see https://github.com/aristanetworks/goarista/blob/master/lanz/proto/lanz.proto
+
+- lanz_congestion_record:
+  - tags:
+    - intf_name
+    - switch_id
+    - port_id
+    - entry_type
+    - traffic_class
+    - fabric_peer_intf_name
+    - source
+    - port
+  - fields:
+    - timestamp        (integer)
+    - queue_size       (integer)
+    - time_of_max_qlen (integer)
+    - tx_latency       (integer)
+    - q_drop_count     (integer)
+
+- lanz_global_buffer_usage_record
+  - tags:
+    - entry_type
+    - source
+    - port
+  - fields:
+    - timestamp   (integer)
+    - buffer_size (integer)
+    - duration    (integer)
+
+
+
+### Sample Queries
+
+Get the max tx_latency for the last hour for all interfaces on all switches.
+```
+SELECT max("tx_latency") AS "max_tx_latency" FROM "congestion_record" WHERE time > now() - 1h GROUP BY time(10s), "hostname", "intf_name"
+```
+
+Get the max tx_latency for the last hour for all interfaces on all switches.
+```
+SELECT max("queue_size") AS "max_queue_size" FROM "congestion_record" WHERE time > now() - 1h GROUP BY time(10s), "hostname", "intf_name"
+```
+
+Get the max buffer_size for over the last hour for all switches.
+```
+SELECT max("buffer_size") AS "max_buffer_size" FROM "global_buffer_usage_record" WHERE time > now() - 1h GROUP BY time(10s), "hostname"
+```
+
+### Example output
+```
+lanz_global_buffer_usage_record,entry_type=2,host=telegraf.int.example.com,port=50001,source=switch01.int.example.com timestamp=158334105824919i,buffer_size=505i,duration=0i 1583341058300643815
+lanz_congestion_record,entry_type=2,host=telegraf.int.example.com,intf_name=Ethernet36,port=50001,port_id=61,source=switch01.int.example.com,switch_id=0,traffic_class=1 time_of_max_qlen=0i,tx_latency=564480i,q_drop_count=0i,timestamp=158334105824919i,queue_size=225i 1583341058300636045
+lanz_global_buffer_usage_record,entry_type=2,host=telegraf.int.example.com,port=50001,source=switch01.int.example.com timestamp=158334105824919i,buffer_size=589i,duration=0i 1583341058300457464
+lanz_congestion_record,entry_type=1,host=telegraf.int.example.com,intf_name=Ethernet36,port=50001,port_id=61,source=switch01.int.example.com,switch_id=0,traffic_class=1 q_drop_count=0i,timestamp=158334105824919i,queue_size=232i,time_of_max_qlen=0i,tx_latency=584640i 1583341058300450302
+```
+
+