Add ~200 more Couchbase metrics via Buckets endpoint (influxdata#9032)

* Couchbase new metrics for buckets

* updated

* update to simplify two different modes.

* cleanup code

* linter telling me to fix things I didn't do

* add include/exclude filter

* update sample config

* appease the linter

* Update README.md

* make all metrics configurable, defaults as just 'basic bucket metrics'

* check error in test

plugins/inputs/couchbase/README.md

@@ -1,4 +1,6 @@
 # Couchbase Input Plugin
+Couchbase is a distributed NoSQL database.
+This plugin gets metrics for each Couchbase node, as well as detailed metrics for each bucket, for a given couchbase server.
 
 ## Configuration:
 
@@ -15,6 +17,9 @@
   ## If no protocol is specified, HTTP is used.
   ## If no port is specified, 8091 is used.
   servers = ["http://localhost:8091"]
+
+  ## Filter bucket fields to include only here.
+  # bucket_stats_included = ["quota_percent_used", "ops_per_sec", "disk_fetches", "item_count", "disk_used", "data_used", "mem_used"]
 ```
 
 ## Measurements:
@@ -35,7 +40,7 @@ Tags:
 - cluster: whatever you called it in `servers` in the configuration, e.g.: `http://couchbase-0.example.com/`)
 - bucket: the name of the couchbase bucket, e.g., `blastro-df`
 
-Fields:
+Default bucket fields:
 - quota_percent_used (unit: percent, example: 68.85424936294555)
 - ops_per_sec (unit: count, example: 5686.789686789687)
 - disk_fetches (unit: count, example: 0.0)
@@ -44,6 +49,223 @@ Fields:
 - data_used (unit: bytes, example: 212179309111.0)
 - mem_used (unit: bytes, example: 202156957464.0)
 
+Additional fields that can be configured with the `bucket_stats_included` option:
+- couch_total_disk_size                    
+- couch_docs_fragmentation
+- couch_views_fragmentation
+- hit_ratio
+- ep_cache_miss_rate
+- ep_resident_items_rate
+- vb_avg_active_queue_age
+- vb_avg_replica_queue_age
+- vb_avg_pending_queue_age
+- vb_avg_total_queue_age
+- vb_active_resident_items_ratio
+- vb_replica_resident_items_ratio
+- vb_pending_resident_items_ratio
+- avg_disk_update_time
+- avg_disk_commit_time
+- avg_bg_wait_time
+- avg_active_timestamp_drift
+- avg_replica_timestamp_drift
+- ep_dcp_views+indexes_count
+- ep_dcp_views+indexes_items_remaining
+- ep_dcp_views+indexes_producer_count
+- ep_dcp_views+indexes_total_backlog_size
+- ep_dcp_views+indexes_items_sent
+- ep_dcp_views+indexes_total_bytes
+- ep_dcp_views+indexes_backoff
+- bg_wait_count
+- bg_wait_total
+- bytes_read
+- bytes_written
+- cas_badval
+- cas_hits
+- cas_misses
+- cmd_get
+- cmd_lookup
+- cmd_set
+- couch_docs_actual_disk_size
+- couch_docs_data_size
+- couch_docs_disk_size
+- couch_spatial_data_size
+- couch_spatial_disk_size
+- couch_spatial_ops
+- couch_views_actual_disk_size
+- couch_views_data_size
+- couch_views_disk_size
+- couch_views_ops
+- curr_connections
+- curr_items
+- curr_items_tot
+- decr_hits
+- decr_misses
+- delete_hits
+- delete_misses
+- disk_commit_count
+- disk_commit_total
+- disk_update_count
+- disk_update_total
+- disk_write_queue
+- ep_active_ahead_exceptions
+- ep_active_hlc_drift
+- ep_active_hlc_drift_count
+- ep_bg_fetched
+- ep_clock_cas_drift_threshold_exceeded
+- ep_data_read_failed
+- ep_data_write_failed
+- ep_dcp_2i_backoff
+- ep_dcp_2i_count
+- ep_dcp_2i_items_remaining
+- ep_dcp_2i_items_sent
+- ep_dcp_2i_producer_count
+- ep_dcp_2i_total_backlog_size
+- ep_dcp_2i_total_bytes
+- ep_dcp_cbas_backoff
+- ep_dcp_cbas_count
+- ep_dcp_cbas_items_remaining
+- ep_dcp_cbas_items_sent
+- ep_dcp_cbas_producer_count
+- ep_dcp_cbas_total_backlog_size
+- ep_dcp_cbas_total_bytes
+- ep_dcp_eventing_backoff
+- ep_dcp_eventing_count
+- ep_dcp_eventing_items_remaining
+- ep_dcp_eventing_items_sent
+- ep_dcp_eventing_producer_count
+- ep_dcp_eventing_total_backlog_size
+- ep_dcp_eventing_total_bytes
+- ep_dcp_fts_backoff
+- ep_dcp_fts_count
+- ep_dcp_fts_items_remaining
+- ep_dcp_fts_items_sent
+- ep_dcp_fts_producer_count
+- ep_dcp_fts_total_backlog_size
+- ep_dcp_fts_total_bytes
+- ep_dcp_other_backoff
+- ep_dcp_other_count
+- ep_dcp_other_items_remaining
+- ep_dcp_other_items_sent
+- ep_dcp_other_producer_count
+- ep_dcp_other_total_backlog_size
+- ep_dcp_other_total_bytes
+- ep_dcp_replica_backoff
+- ep_dcp_replica_count
+- ep_dcp_replica_items_remaining
+- ep_dcp_replica_items_sent
+- ep_dcp_replica_producer_count
+- ep_dcp_replica_total_backlog_size
+- ep_dcp_replica_total_bytes
+- ep_dcp_views_backoff
+- ep_dcp_views_count
+- ep_dcp_views_items_remaining
+- ep_dcp_views_items_sent
+- ep_dcp_views_producer_count
+- ep_dcp_views_total_backlog_size
+- ep_dcp_views_total_bytes
+- ep_dcp_xdcr_backoff
+- ep_dcp_xdcr_count
+- ep_dcp_xdcr_items_remaining
+- ep_dcp_xdcr_items_sent
+- ep_dcp_xdcr_producer_count
+- ep_dcp_xdcr_total_backlog_size
+- ep_dcp_xdcr_total_bytes
+- ep_diskqueue_drain
+- ep_diskqueue_fill
+- ep_diskqueue_items
+- ep_flusher_todo
+- ep_item_commit_failed
+- ep_kv_size
+- ep_max_size
+- ep_mem_high_wat
+- ep_mem_low_wat
+- ep_meta_data_memory
+- ep_num_non_resident
+- ep_num_ops_del_meta
+- ep_num_ops_del_ret_meta
+- ep_num_ops_get_meta
+- ep_num_ops_set_meta
+- ep_num_ops_set_ret_meta
+- ep_num_value_ejects
+- ep_oom_errors
+- ep_ops_create
+- ep_ops_update
+- ep_overhead
+- ep_queue_size
+- ep_replica_ahead_exceptions
+- ep_replica_hlc_drift
+- ep_replica_hlc_drift_count
+- ep_tmp_oom_errors
+- ep_vb_total
+- evictions
+- get_hits
+- get_misses
+- incr_hits
+- incr_misses
+- mem_used
+- misses
+- ops
+- timestamp
+- vb_active_eject
+- vb_active_itm_memory
+- vb_active_meta_data_memory
+- vb_active_num
+- vb_active_num_non_resident
+- vb_active_ops_create
+- vb_active_ops_update
+- vb_active_queue_age
+- vb_active_queue_drain
+- vb_active_queue_fill
+- vb_active_queue_size
+- vb_active_sync_write_aborted_count
+- vb_active_sync_write_accepted_count
+- vb_active_sync_write_committed_count
+- vb_pending_curr_items
+- vb_pending_eject
+- vb_pending_itm_memory
+- vb_pending_meta_data_memory
+- vb_pending_num
+- vb_pending_num_non_resident
+- vb_pending_ops_create
+- vb_pending_ops_update
+- vb_pending_queue_age
+- vb_pending_queue_drain
+- vb_pending_queue_fill
+- vb_pending_queue_size
+- vb_replica_curr_items
+- vb_replica_eject
+- vb_replica_itm_memory
+- vb_replica_meta_data_memory
+- vb_replica_num
+- vb_replica_num_non_resident
+- vb_replica_ops_create
+- vb_replica_ops_update
+- vb_replica_queue_age
+- vb_replica_queue_drain
+- vb_replica_queue_fill
+- vb_replica_queue_size
+- vb_total_queue_age
+- xdc_ops
+- allocstall
+- cpu_cores_available
+- cpu_irq_rate
+- cpu_stolen_rate
+- cpu_sys_rate
+- cpu_user_rate
+- cpu_utilization_rate
+- hibernated_requests
+- hibernated_waked
+- mem_actual_free
+- mem_actual_used
+- mem_free
+- mem_limit
+- mem_total
+- mem_used_sys
+- odp_report_failed
+- rest_requests
+- swap_total
+- swap_used
+
 
 ## Example output