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Prometheus

By Kong Inc.

Expose metrics related to Kong and proxied upstream services in Prometheus exposition format, which can be scraped by a Prometheus Server.

Metrics tracked by this plugin are available on both the Admin API and Status API at the http://localhost:<port>/metrics endpoint. Note that the URL to those APIs will be specific to your installation; see Accessing the metrics.

This plugin records and exposes metrics at the node level. Your Prometheus server will need to discover all Kong nodes via a service discovery mechanism, and consume data from each node’s configured /metrics endpoint.

Grafana dashboard

Metrics exported by the plugin can be graphed in Grafana using a drop-in dashboard: https://grafana.com/grafana/dashboards/7424-kong-official/.

Available metrics

  • DB reachability: A gauge type with a value of 0 or 1, which represents whether DB can be reached by a Kong node.
  • Connections: Various Nginx connection metrics like active, reading, writing, and number of accepted connections.
  • Dataplane Status: The last seen timestamp, config hash, config sync status and certificate expiration timestamp for data plane nodes is exported to control plane.
  • Enterprise License Information: The Kong Gateway license expiration date, features and license signature. Those metrics are only exported on Kong Gateway.
  • DB Entity Count : A gauge metric that measures the current number of database entities.
  • Number of Nginx timers : A gauge metric that measures the total number of Nginx timers, in Running or Pending state.

Following metrics are disabled by default as it may create high cardinality of metrics and may cause performance issues:

When status_code_metrics is set to true:

  • Status codes: HTTP status codes returned by upstream services. These are available per service, across all services, and per route per consumer.

When latency_metrics is set to true:

  • Latencies Histograms: Latency (in ms), as measured at Kong:
    • Request: Total time taken by Kong and upstream services to serve requests.
    • Kong: Time taken for Kong to route a request and run all configured plugins.
    • Upstream: Time taken by the upstream service to respond to requests.

When bandwidth_metrics is set to true:

  • Bandwidth: Total Bandwidth (egress/ingress) flowing through Kong. This metric is available per service and as a sum across all services.

When upstream_health_metrics is set to true:

  • Target Health: The healthiness status (healthchecks_off, healthy, unhealthy, or dns_error) of targets belonging to a given upstream as well as their subsystem (http or stream).

Here is an example of output you could expect from the /metrics endpoint:

curl -i http://localhost:8001/metrics

Response:

HTTP/1.1 200 OK
Server: openresty/1.15.8.3
Date: Tue, 7 Jun 2020 16:35:40 GMT
Content-Type: text/plain; charset=UTF-8
Transfer-Encoding: chunked
Connection: keep-alive
Access-Control-Allow-Origin: *

# HELP kong_bandwidth_bytes Total bandwidth (ingress/egress) throughput in bytes
# TYPE kong_bandwidth_bytes counter
kong_bandwidth_bytes{service="google",route="google.route-1",direction="egress",consumer=""} 264
kong_bandwidth_bytes{service="google",route="google.route-1",direction="ingress",consumer=""} 93
# HELP kong_datastore_reachable Datastore reachable from Kong, 0 is unreachable
# TYPE kong_datastore_reachable gauge
kong_datastore_reachable 1
# HELP kong_http_requests_total HTTP status codes per consumer/service/route in Kong
# TYPE kong_http_requests_total counter
kong_http_requests_total{service="google",route="google.route-1",code="200",source="service",consumer=""} 1
# HELP kong_node_info Kong Node metadata information
# TYPE kong_node_info gauge
kong_node_info{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",version="3.0.0"} 1
# HELP kong_kong_latency_ms Latency added by Kong and enabled plugins for each service/route in Kong
# TYPE kong_kong_latency_ms histogram
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="5"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="7"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="10"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="15"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="20"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="30"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="50"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="75"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="100"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="200"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="500"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="750"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="1000"} 1
kong_kong_latency_ms_bucket{service="google",route="google.route-1",le="+Inf"} 1
kong_kong_latency_ms_count{service="google",route="google.route-1"} 1
kong_kong_latency_ms_sum{service="google",route="google.route-1"} 4
# HELP kong_memory_lua_shared_dict_bytes Allocated slabs in bytes in a shared_dict
# TYPE kong_memory_lua_shared_dict_bytes gauge
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong",kong_subsystem="http"} 40960
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_cluster_events",kong_subsystem="http"} 40960
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_core_db_cache",kong_subsystem="http"} 823296
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_core_db_cache_miss",kong_subsystem="http"} 90112
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_db_cache",kong_subsystem="http"} 794624
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_db_cache_miss",kong_subsystem="http"} 86016
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_healthchecks",kong_subsystem="http"} 40960
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_locks",kong_subsystem="http"} 61440
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_process_events",kong_subsystem="http"} 40960
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_rate_limiting_counters",kong_subsystem="http"} 86016
kong_memory_lua_shared_dict_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="prometheus_metrics",kong_subsystem="http"} 57344
# HELP kong_memory_lua_shared_dict_total_bytes Total capacity in bytes of a shared_dict
# TYPE kong_memory_lua_shared_dict_total_bytes gauge
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong",kong_subsystem="http"} 5242880
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_cluster_events",kong_subsystem="http"} 5242880
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_core_db_cache",kong_subsystem="http"} 134217728
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_core_db_cache_miss",kong_subsystem="http"} 12582912
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_db_cache",kong_subsystem="http"} 134217728
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_db_cache_miss",kong_subsystem="http"} 12582912
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_healthchecks",kong_subsystem="http"} 5242880
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_locks",kong_subsystem="http"} 8388608
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_process_events",kong_subsystem="http"} 5242880
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="kong_rate_limiting_counters",kong_subsystem="http"} 12582912
kong_memory_lua_shared_dict_total_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",shared_dict="prometheus_metrics",kong_subsystem="http"} 5242880
# HELP kong_memory_workers_lua_vms_bytes Allocated bytes in worker Lua VM
# TYPE kong_memory_workers_lua_vms_bytes gauge
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21173",kong_subsystem="http"} 64329517
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21174",kong_subsystem="http"} 46314808
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21175",kong_subsystem="http"} 46681598
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21176",kong_subsystem="http"} 46637209
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21177",kong_subsystem="http"} 46234336
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21178",kong_subsystem="http"} 46180420
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21179",kong_subsystem="http"} 46161105
kong_memory_workers_lua_vms_bytes{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",pid="21180",kong_subsystem="http"} 46366877
# HELP kong_nginx_connections_total Number of connections by subsystem
# TYPE kong_nginx_connections_total gauge
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="accepted"} 296
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="active"} 9
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="handled"} 296
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="reading"} 0
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="total"} 296
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="waiting"} 0
kong_nginx_connections_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http",state="writing"} 9
# HELP kong_nginx_metric_errors_total Number of nginx-lua-prometheus errors
# TYPE kong_nginx_metric_errors_total counter
kong_nginx_metric_errors_total 0
# HELP kong_nginx_requests_total Total number of requests
# TYPE kong_nginx_requests_total gauge
kong_nginx_requests_total{node_id="849373c5-45c1-4c1d-b595-fdeaea6daed8",subsystem="http"} 296
# HELP kong_nginx_timers Number of Nginx timers
# TYPE kong_nginx_timers gauge
kong_nginx_timers{state="pending"} 1
kong_nginx_timers{state="running"} 39
# HELP kong_request_latency_ms Total latency incurred during requests for each service/route in Kong
# TYPE kong_request_latency_ms histogram
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="25"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="50"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="80"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="100"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="250"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="400"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="700"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="1000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="2000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="5000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="10000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="30000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="60000"} 1
kong_request_latency_ms_bucket{service="google",route="google.route-1",le="+Inf"} 1
kong_request_latency_ms_count{service="google",route="google.route-1"} 1
kong_request_latency_ms_sum{service="google",route="google.route-1"} 6
# HELP kong_upstream_latency_ms Latency added by upstream response for each service/route in Kong
# TYPE kong_upstream_latency_ms histogram
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="25"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="50"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="80"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="100"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="250"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="400"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="700"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="1000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="2000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="5000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="10000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="30000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="60000"} 1
kong_upstream_latency_ms_bucket{service="google",route="google.route-1",le="+Inf"} 1
kong_upstream_latency_ms_count{service="google",route="google.route-1"} 1
kong_upstream_latency_ms_sum{service="google",route="google.route-1"} 2

Note: Upstream targets’ health information is exported once per subsystem. If both stream and HTTP listeners are enabled, targets’ health will appear twice. Health metrics have a subsystem label to indicate which subsystem the metric refers to.

Accessing the metrics

In most configurations, the Kong Admin API will be behind a firewall or would need to be set up to require authentication. Here are a couple of options to allow access to the /metrics endpoint to Prometheus:

  1. If the Status API is enabled, then its /metrics endpoint can be used. This is the preferred method.

  2. The /metrics endpoint is also available on the Admin API, which can be used if the Status API is not enabled. Note that this endpoint is unavailable when RBAC is enabled on the Admin API (Prometheus does not support Key-Auth to pass the token).