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Vitals Metrics
Vitals metrics fall into two categories:
- Health Metrics — for monitoring the health of a Kong cluster
- Traffic Metrics — for monitoring the usage of upstream services
All metrics are collected at 1-second intervals and aggregated into 1-minute intervals. The 1-second intervals are retained for one hour. The 1-minute intervals are retained for 25 hours.
If longer retention times are needed, the Vitals API can be used to pull metrics out of Kong and into a data retention tool.
Health Metrics
Health metrics give insight into the performance of a Kong cluster; for example, how many requests the cluster is processing and the latency on those requests.
Health metrics are tracked for each node in a cluster as well as for the cluster as a whole. In Kong, a node is a running process with a unique identifier, configuration, cache layout, and connections to both Kong’s data stores and the upstream APIs it proxies. Note that node identifiers are unique to the process, and not to the host on which the process runs. In other words, each Kong restart results in a new node, and therefore a new node ID.
Latency
The Vitals API may return null for Latency metrics. This occurs when no API requests were proxied during the time frame. Null latencies are not graphed in Kong Manager; periods with null latencies appear as gaps in Vitals charts.
Proxy Latency (Request)
The Proxy Latency metrics are the min, max, and average values for the time, in milliseconds, that the Kong proxy spends processing API proxy requests. This includes time to execute plugins that run in the access phase and the DNS lookup time. This does not include time spent in Kong’s load balancer, time spent sending the request to the upstream, or time spent on the response.
These metrics are referenced in the Vitals API with the following labels: latency_proxy_request_min_ms, latency_proxy_request_max_ms, latency_proxy_request_avg_ms.
Latency is not reported when a request is prematurely ended by Kong (e.g., bad auth, rate limited, etc.). Note that this differs from the Total Requests metric that does count such requests.
Upstream Latency
The Upstream Latency metrics are the min, max, and average values for the time elapsed, in milliseconds, between Kong sending requests upstream and Kong receiving the first bytes of responses from upstream.
These metrics are referenced in the Vitals API with the following labels: latency_upstream_min_ms, latency_upstream_max_ms, latency_upstream_avg_ms.
Data store Cache
Data store Cache Hit/Miss
The Data store Cache Hit/Miss metrics are the count of requests to Kong’s node-level data store cache. When Kong workers need configuration information to respond to a given API proxy request, they first check their worker-specific cache (also known as L1 cache), then if the information isn’t available they check the node-wide data store cache (also known as L2 cache). If neither cache contains the necessary information, Kong requests it from the data store.
A Hit indicates that an entity was retrieved from the data store cache. A Miss indicates that the record had to be fetched from the data store. Not every API request will result in data store cache access; some entities will be retrieved from Kong’s worker-specific cache memory.
These metrics are referenced in the Vitals API with the following labels: cache_datastore_hits_total, cache_datastore_misses_total.
Data store Cache Hit Ratio
This metric contains the ratio of data store cache hits to the total count of data store cache requests.
Note: Data store Cache Hit Ratio cannot be calculated for time indices with no hits and no misses.
Traffic Metrics
Traffic metrics provide insight into which of your services are being used, who is using them, and how they are responding.
Request Counts
Total Requests
This metric is the count of all API proxy requests received. This includes requests that were rejected due to rate-limiting, failed authentication, etc.
This metric is referenced in the Vitals API with the following label: requests_proxy_total.
Requests Per Consumer
This metric is the count of all API proxy requests received from each specific consumer. Consumers are identified by credentials in their requests (e.g., API key, OAuth token) as required by the Kong Auth plugins in use.
This metric is referenced in the Vitals API with the following label: requests_consumer_total.
Status Codes
Total Status Code Classes
This metric is the count of all status codes grouped by status code class (e.g. 4xx, 5xx).
This metric is referenced in the Vitals API with the following label: status_code_classes_total.
Total Status Codes per Service
This metric is the total count of each specific status code for a given service.
This metric is referenced in the Vitals API with the following label: status_codes_per_service_total.
Total Status Codes per Route
This metric is the total count of each specific status code for a given route.
This metric is referenced in the Vitals API with the following label: status_codes_per_route_total.
Total Status Codes per Consumer
This metric is the total count of each specific status code for a given consumer.
This metric is referenced in the Vitals API with the following label: status_codes_per_consumer_total.
Total Status Codes per Consumer Per Route
This metric is the total count of each specific status code for a given consumer and route.
This metric is referenced in the Vitals API with the following label: status_codes_per_consumer_route_total.