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94 lines
2.3 KiB
OCaml
94 lines
2.3 KiB
OCaml
(** Expose metrics over HTTP in the prometheus format.
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This sub-library [tiny_httpd.prometheus] provides definitions
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for counters, gauges, and histogram, and endpoints to expose
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them for {{: https://prometheus.io/} Prometheus} to scrape them.
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@since 0.16
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*)
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type tags = (string * string) list
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(** Registry for metrics. *)
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module Registry : sig
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type t
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(** The registry contains a group of metrics *)
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val create : unit -> t
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val on_will_emit : t -> (unit -> unit) -> unit
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(** [on_will_emit registry f] calls [f()] every time
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[emit buf registry] is called (before the metrics start being emitted). This
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is useful to update some metrics on demand. *)
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val emit : Buffer.t -> t -> unit
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(** Write metrics into the given buffer. The buffer will be
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cleared first thing. *)
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val emit_str : t -> string
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end
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val global : Registry.t
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(** Counters *)
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module Counter : sig
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type t
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(** A counter, monotonically increasing *)
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val create : Registry.t -> ?tags:tags -> ?descr:string -> string -> t
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val incr : t -> unit
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val incr_by : t -> int -> unit
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val incr_to : t -> int -> unit
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(** Increment to the given number. If it's lower than the current
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value this does nothing *)
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end
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(** Gauges *)
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module Gauge : sig
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type t
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(** A gauge, taking arbitrary values *)
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val create : Registry.t -> ?tags:tags -> ?descr:string -> string -> t
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val set : t -> int -> unit
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val incr : t -> unit
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val incr_by : t -> int -> unit
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val decr : t -> unit
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val decr_by : t -> int -> unit
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end
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module Histogram : sig
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type t
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(** Histogram *)
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val create :
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Registry.t ->
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?tags:tags ->
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?descr:string ->
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buckets:float list ->
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string ->
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t
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val add : t -> float -> unit
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end
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val http_middleware : Registry.t -> Server.Middleware.t
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(** Middleware to get basic metrics about HTTP requests *)
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val add_route_to_server : Server.t -> Registry.t -> unit
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(** Add a "/metrics" route to the server *)
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val instrument_server : Server.t -> Registry.t -> unit
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(** Add middleware and route *)
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module GC_metrics : sig
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type t
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val create : Registry.t -> t
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val update : t -> unit
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val create_and_update_before_emit : Registry.t -> unit
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(** [create_and_update_before_emit reg] creates new GC metrics,
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adds them to the registry, and uses {!Registry.on_will_emit}
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to {!update} the metrics every time the registry is polled. *)
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end
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