json-exporter's Introduction

Json Exporter

This Prometheus exporter operates similar to the Blackbox exporters. It downloads a JSON file and provides a numerical gauge value from within that file. Which value to pick is defined through JsonPath.

Parameters

target: URL / Json-file to download
jsonpath: the field name to read the value from, this follows the syntax provided by oliveagle/jsonpath

Docker usage

docker build -t json_exporter .
docker run -p 9116:9116 -d json_exporter /json_exporter

To clean up multistage build artifacts afterwards use

docker image prune --filter label=stage=tempbuilder

The related metrics can then be found under:

http://localhost:9116/probe?target=http://validate.jsontest.com/?json=%7B%22key%22:%22value%22%7D&jsonpath=$.parse_time_nanoseconds

Prometheus Configuration

The json exporter needs to be passed the target and the json as a parameter, this can be done with relabelling.

Example config:

scrape_configs:
  - job_name: 'json'
    metrics_path: /probe
    params:
      jsonpath: [$.parse_time_nanoseconds] # Look for the nanoseconds field
    static_configs:
      - targets:
        - http://validate.jsontest.com/?json=%7B%22key%22:%22value%22%7D
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: 127.0.0.1:9116  # Json exporter.
    metric_relabel_configs:
      - source_labels: value
        target_label: parse_time