Documentation
¶
Overview ¶
Package metrics is a small, dependency-free Prometheus metrics registry. It implements just enough of the text exposition format (counters, histograms, gauges) to instrument Legant without pulling in the full client library — in keeping with the project's lean-dependency posture. The default registry is pre-loaded with HTTP request metrics, a Go-runtime collector, and the product-level counters (token exchanges, revocations, gateway calls).
Index ¶
- Variables
- func Handler() http.Handler
- func Middleware(next http.Handler) http.Handler
- func SetBuildInfo(version string)
- type CounterVec
- type GaugeVec
- type HistogramVec
- type Registry
- func (r *Registry) AddCollector(fn func(w io.Writer))
- func (r *Registry) AddGoCollector()
- func (r *Registry) Handler() http.Handler
- func (r *Registry) NewCounter(name, help string, labels ...string) *CounterVec
- func (r *Registry) NewGauge(name, help string, labels ...string) *GaugeVec
- func (r *Registry) NewHistogram(name, help string, buckets []float64, labels ...string) *HistogramVec
- func (r *Registry) Render(w io.Writer)
- func (r *Registry) SetBuildInfo(version, goVersion string)
Constants ¶
This section is empty.
Variables ¶
var ( HTTPRequestsTotal = Default.NewCounter( "legant_http_requests_total", "Total HTTP requests handled, by method, route pattern, and status code.", "method", "route", "code") HTTPRequestDuration = Default.NewHistogram( "legant_http_request_duration_seconds", "HTTP request latency in seconds, by method and route pattern.", DefaultBuckets, "method", "route") HTTPRequestsInFlight = Default.NewGauge( "legant_http_requests_in_flight", "Requests currently being served.") // TokenExchangesTotal counts RFC 8693 token-exchange attempts by outcome. TokenExchangesTotal = Default.NewCounter( "legant_token_exchanges_total", "RFC 8693 token-exchange attempts, by result (success|error).", "result") // DelegationsTotal counts delegations created (the top of the funnel): a user // consenting to delegate to an agent, or an agent re-delegating to a sub-agent. DelegationsTotal = Default.NewCounter( "legant_delegations_total", "Delegations created, by kind (consent|redelegate).", "kind") // TokensMintedTotal counts composite delegation tokens actually signed. TokensMintedTotal = Default.NewCounter( "legant_tokens_minted_total", "Composite delegation tokens minted, by source (exchange|gateway).", "source") // RevocationsTotal counts revocation events. RevocationsTotal = Default.NewCounter( "legant_revocations_total", "Revocation events, by kind (token|delegation).", "kind") // RevocationCheckErrorsTotal counts revocation-store lookup failures. These // fail closed (the request is denied), so without a metric they are invisible — // a spike means the store is unhealthy and tokens are being rejected. RevocationCheckErrorsTotal = Default.NewCounter( "legant_revocation_check_errors_total", "Revocation-store lookup failures, by component (gateway|introspection).", "component") // GatewayCallsTotal counts MCP gateway tool calls by upstream and decision. GatewayCallsTotal = Default.NewCounter( "legant_gateway_calls_total", "MCP gateway tool calls, by upstream and decision (allow|deny|unauthorized|error).", "upstream", "decision") )
Product-level metrics. These are incremented at the relevant choke points (token exchange, revocation, gateway tool calls) to give an at-a-glance view of delegation activity that raw HTTP counts cannot.
var Default = NewRegistry()
Default is the process-wide registry. It is pre-loaded with HTTP request metrics, a Go-runtime collector, and the product-level counters below.
var DefaultBuckets = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}
DefaultBuckets are the request-duration histogram buckets, in seconds.
Functions ¶
func Middleware ¶
Middleware records request count and latency for every HTTP request, labeled by method, the chi route pattern (bounded cardinality — never the raw path), and status code.
func SetBuildInfo ¶
func SetBuildInfo(version string)
SetBuildInfo records the running version as a build_info gauge.
Types ¶
type CounterVec ¶
type CounterVec struct {
// contains filtered or unexported fields
}
CounterVec is a family of monotonically increasing counters partitioned by a fixed set of label names.
func (*CounterVec) Add ¶
func (c *CounterVec) Add(n uint64, labelValues ...string)
Add adds n to the counter for the given label values.
func (*CounterVec) Inc ¶
func (c *CounterVec) Inc(labelValues ...string)
Inc increments the counter for the given label values by one.
type GaugeVec ¶
type GaugeVec struct {
// contains filtered or unexported fields
}
GaugeVec is a family of gauges (values that go up and down) partitioned by a fixed set of label names. Values are integers, sufficient for counts such as in-flight requests.
type HistogramVec ¶
type HistogramVec struct {
// contains filtered or unexported fields
}
HistogramVec is a family of histograms partitioned by a fixed set of labels.
func (*HistogramVec) Observe ¶
func (h *HistogramVec) Observe(v float64, labelValues ...string)
Observe records a single observation for the given label values.
type Registry ¶
type Registry struct {
// contains filtered or unexported fields
}
Registry holds a set of metric families and renders them in the Prometheus text exposition format. It is safe for concurrent use.
func (*Registry) AddCollector ¶
AddCollector registers a callback that writes additional exposition lines at scrape time (used for runtime gauges sampled on demand).
func (*Registry) AddGoCollector ¶
func (r *Registry) AddGoCollector()
AddGoCollector registers gauges sampled from the Go runtime at scrape time.
func (*Registry) NewCounter ¶
func (r *Registry) NewCounter(name, help string, labels ...string) *CounterVec
NewCounter registers and returns a labeled counter family.
func (*Registry) NewGauge ¶
NewGauge registers and returns a labeled gauge family (a value that can go up and down, e.g. in-flight requests).
func (*Registry) NewHistogram ¶
func (r *Registry) NewHistogram(name, help string, buckets []float64, labels ...string) *HistogramVec
NewHistogram registers and returns a labeled histogram family.
func (*Registry) SetBuildInfo ¶
SetBuildInfo registers a constant build_info gauge labeled with the version.
Source Files