APM Gateway

Service: apm-gateway · Port: 8101

apm-gateway serves application performance data: how many requests each service handles, how fast, and how many fail — per service and per endpoint. It runs PromQL against Prometheus and returns structured JSON, so the dashboard, agents and scripts don't need to know PromQL. It stores nothing itself.

What it answers

Question	Endpoint	PromQL
How busy is each service?	/api/v1/services/metrics	sum by (app, namespace) (rate(http_requests_total[5m]))
Which endpoints are slowest?	/api/v1/endpoints/slowest	topk(10, histogram_quantile(0.99, sum by (le, handler, method) (rate(http_request_duration_seconds_bucket[5m]))))
Which endpoints fail most?	/api/v1/endpoints/erroring	topk(10, sum by (handler, method) (rate(http_requests_total{status=~"5.."}[5m])))

Metric labels

apm-gateway expects the standard labels used by Prometheus client libraries:

Label	Meaning
app or service	The workload.
namespace	The Kubernetes namespace.
handler	The route or endpoint.
method	The HTTP method.
status	The HTTP status code.

Using a service mesh or a framework with different label names? Map them in configuration — for example, for Istio:

APM_LABEL_MAP: "app=destination_service_name,status=response_code,handler=request_operation"
APM_REQUESTS_METRIC: "istio_requests_total"
APM_DURATION_METRIC: "istio_request_duration_milliseconds_bucket"

REST API

Method	Path	Description
GET	/api/v1/services/metrics	Request rate, p50/p95/p99 latency and error rate per service (?namespace=).
GET	/api/v1/services/{service}/timeseries	A service's metrics over time (?from=&to=&step=).
GET	/api/v1/endpoints/slowest	The ten slowest endpoints by p99 latency.
GET	/api/v1/endpoints/erroring	The ten endpoints with the most 5xx errors.
POST	/api/v1/query	Run a PromQL query (used by the Optimizer and troubleshooter).
GET	/healthz	Health check.

Tenant users see only their own services.

Configuration

Variable	Default	Description
PROMETHEUS_URL	http://kube-prometheus-stack-prometheus.monitoring:9090	Prometheus.
APM_LABEL_MAP	—	Label name mappings (standard=yours, comma-separated).
APM_REQUESTS_METRIC	http_requests_total	Request counter metric.
APM_DURATION_METRIC	http_request_duration_seconds_bucket	Latency histogram metric.
AUTH_JWT_ACCESS_SECRET	—	Validates tokens.
PORT	8101	HTTP port.