Prometheus HTTP API client for Clojure

Client library wrapper around Prometheus HTTP API.

It provides the extraction of only relevant data from the responses and, for endpoints returning time series, automated response conversion to a more Clojure-friendly format.

As of writing, 100% of the endpoints are implemented, each corresponding to a function with extensive documentation.

Installation

Add the following dependency to your project.clj file:

[eigenbahn/prometheus-api-client "1.0.0"]

General Usage

Connection

All methods take a connection conn as a first argument. It's just a simple map in the form:

{:url "<prometheus_base_url>"}

The :url field value must contain the base URL of the Prometheus instance. It is not expected to contain the "/api/v1" part.

So to connect to a localhost instance:

(def prom-conn {:url "http://localhost:9090"})

Time instants

Arguments corresponding to a time instant (and by extension the boundaries of a time range) can be in the following format:

• any valid Clojure inst object
• UNIX timestamp with second precision, with optional milliseconds after the comma, in string or number. E.g.: "1600093006", 1600093006, "1600093006.148", 1600093006.148.
• an RFC3339 string. E.g. "1996-12-19T16:39:57-08:00".

Optional arguments

All optional arguments are keyword arguments.

Error / Exception handling

Errors translate to HTTP error codes, throwing exceptions.

As we are relying on clj-http.client, those exceptions are Slingshot Stones. Refer to this section to see how to handle them.

Result extraction & conversion

By default, only the most sensible data in the API response is returned by each function.

This can be tweaked by adjusting the value of dynamic var content-level:

• ::http-client: raw value from clj-http.client, good for debugging
• ::body: HTTP body parsing into a clojure data structure
• ::data: "data" part of the prometheus response
• ::best: only the most sensible data for each endpoint (default)

Likewise, we by default convert time series into more clojure-friendly data structures (maps) with timestamps converted to inst and used as keys and values parsed when scalar instead of just strings. This can be disabled by setting convert-result to false.

Example usage

All the endpoints are implemented. Only the TSDB querying-related ones are presented here.

Querying time series

;; a single point at a given time (/query endpoint)
(prometheus-api.client/query prom-conn "scrape_duration_seconds" :at 1600093006.148)
;; -> [{"value" {#inst "2020-09-14T14:16:46.148000000-00:00" 0.004643278},
;;      "metric"
;;      {"job" "prometheus",
;;       "instance" "localhost:9090",
;;       "__name__" "scrape_duration_seconds"}}]

;; the last point
(prometheus-api.client/query prom-conn "scrape_duration_seconds")
;; -> [{"value" {#inst "2020-09-15T16:31:02.564000000-00:00" 0.005696021},
;;      "metric"
;;      {"job" "prometheus",
;;       "instance" "localhost:9090",
;;       "__name__" "scrape_duration_seconds"}}]

;; over a time range (/query-range endpoint)
(prometheus-api.client/query prom-conn "scrape_duration_seconds"
                             #inst "2020-09-14T12:16:04.148000000-00:00" ; from
                             #inst "2020-09-14T14:15:50.148000000-00:00" ; to
                             14)                                         ; step (in seconds unless unit specified)
;; -> [{"values"
;;      {#inst "2020-09-14T12:47:02.000000000-00:00" 0.00457012,
;;       #inst "2020-09-14T12:17:10.000000000-00:00" 0.00456644,
;;       ...
;;       #inst "2020-09-14T14:13:36.000000000-00:00" 0.004636848},
;;      "metric"
;;      {"job" "prometheus",
;;       "instance" "localhost:9090",
;;       "__name__" "scrape_duration_seconds"}}]

List labels & series

;; list of label names (/labels endpoint)
(prometheus-api.client/labels prom-conn)
;; -> ["__name__" "branch" "call" ...]

;; list of values for a given label (/label/<label_name>/values endpoint)
(prometheus-api.client/values-for-label prom-conn "role")
;; -> ["endpoints" "ingress" "node" "pod" "service"]

;; list series by series matchers (/series endpoint)
(prometheus-api.client/series prom-conn ["up" "process_start_time_seconds{job=\"prometheus\"}"])
;; -> [{"job" "prometheus",
;;      "instance" "localhost:9090",
;;      "__name__" "process_start_time_seconds"}
;;     {"job" "prometheus", "instance" "localhost:9090", "__name__" "up"}]

Similar projects & acknowledgement

Project inspired by the excellent full-spectrum/influxdb-client library for InfluxDB.