firehose

Java EE 7+ metrics gateway for prometheus

The firehose service (16kB Thin WAR) gathers metrics emitted from JSON / text (currently only JSON is supported) HTTP endpoint and converts them into prometheus compliant metrics.

The prometheus metrics are exposed via the: http://[HOST]:[8080]/firehose/resources/metrics/{metrics-name} uri in prometheus format.

Metrics from all registered endpoints can be fetched at once via HTTP http://[HOST]:[8080]/firehose/resources/metrics/

Installation

Start firehose in the same docker network as the monitored resources and start it with docker run -d -p 8080:8080 --name firehose airhacks/firehose or deploy the WAR to a Java EE 7 container running on Java 8.

A sample configuration is used for testing. Prometheus, a sample-service and firehose are started:

version: '3.0'
services:
  prometheus:
    build: prometheus-firehose
    ports:
    - "9090:9090"
    links:
    - firehose
  firehose:
    image: airhacks/firehose
    env_file: metrics.env
    ports:
    - "8080:8080"
    links:
    - sample-service
  sample-service:
    image: airhacks/sample-service
    ports:
    - "8282:8080"

sample-service is configured in an metrics.env file and provided at starttime:

# Sample service configuration
firehose.sample-service.uri=http://sample-service:8080/sample-service/resources/metrics
# prometheus does not allow dashes -> name changed to sampleservice
firehose.sample-service.application=sampleservice

Configuration management

To gather a remote metric at least the uri with the fully qualified value, e.g.: http://sample-service:8080/sample-service/resources/metrics is required.

The properties (required by prometheus):

1. application (e.g. "sampleservice"
2. component (e.g. "MetricsResource"")
3. units (e.g. "requests")
4. suffix (e.g. "total")

are usually provided by the monitored endpoint as json, but can be overriden with environment entries, like e.g.

sampleservice.application=sample

at startup time.

The environment variables can be overriden again by the REST configuration endpoint:

1. create or update a metric

Setup "sample-service" metric to be fetched from http://sample-service:8080/sample-service/resources/metrics and exposed via http://[HOST]:[8080]/firehose/resources/metrics/sample-service:

curl -i -H"Content-type: application/json" -XPUT -d'{"uri":"http://sample-service:8080/sample-service/resources/metrics"}' http://localhost:8080/firehose/resources/configurations/sample-service

This endpoint return 201 for creation and 204 for update.

2. list all metrics

curl -i http://localhost:8080/firehose/resources/configurations/

3. delete a metric

delete a metric with the name "sample-service"

curl -XDELETE http://localhost:8080/firehose/resources/configurations/sample-service

Prometheus endpoint

The preconfigured endpoint are available under the URI: http://[HOST]:[8080]/firehose/resources/metrics/{metrics-name}

test it with: e.g. curl -i http://localhost:8080/firehose/resources/metrics/sample-service

Build

1. git clone https://github.com/AdamBien/firehose
2. cd firehose && mvn clean install && docker build -t airhacks/firehose .
3. cd sample-service && mvn clean install && docker build -t airhacks/sample-service .
4. docker-compose up -d

Base image for firehose and sample apps were taken from docklands

See you at Java EE Performance, Monitoring and Troubleshooting and/or Java EE Microservices workshops