Monitoring with Prometheus and Grafana

Prometheus is open source system and alerting toolkit for monitoring and alerting. It's a time series database that collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if some condition is observed to be true. Grafana is an open source visualization and analytics software.

It's a pretty common solution to use Prometheus to collect and store monitoring data, and Grafana to visualize it.

Platformatic can be configured to expose Prometheus metrics:

...
  "metrics": {
    "port": 9091,
    "auth": {
      "username": "platformatic",
      "password": "mysecret"
    }
  }
...

In this case, we are exposing the metrics on port 9091 (defaults to 9090), and we are using basic authentication to protect the endpoint. We can also specify the IP address to bind to (defaults to 0.0.0.0). Note that the metrics port is not the default in this configuration. This is because if you want to test the integration running both Prometheus and Platformatic on the same host, Prometheus starts on 9090 port too.

Prometheus recommends using a port different from the main application port for serving the metrics. But, it is possible to serve metrics on the same port as the application by setting "server": "parent" in the metrics configuration. It is also possible to change the endpoint on which metrics are being served by passing the endpoint property. The following example configuration illustrates this:

...
  "metrics": {
    "server": "parent",
    "endpoint": "/platformatic-app-metrics",
    "auth": {
      "username": "platformatic",
      "password": "mysecret"
    }
  }
...

All the configuration settings are optional. To use the default settings, set "metrics": true. See the configuration reference for more details.md#metrics

caution

Use environment variable placeholders in your Platformatic DB configuration file to avoid exposing credentials.

Custom Metrics

When running an application inside Platformatic, you can register and export custom metrics by accessing the application registry. Do to so, access it via globalThis.platformatic.prometheus.registry. In order to ensure the maximum compatibility between Platformatic metrics and custom metrics, there is also a globalThis.platformatic.prometheus.client, which is the same version of the prom-client used by Platformatic internally.

Putting everything together, here it is an example of how to register a custom metric:

const { client, registry } = globalThis.platformatic.prometheus

// Register the metric
const customMetrics = new client.Counter({ name: 'custom', help: 'Custom Description', registers: [registry] })

// Later increase the value
customMetrics.inc(123)

note

Remember that it is a good practice to register metrics as soon as possible during the boot phase.

Prometheus Configuration

This is an example of a minimal Prometheus configuration to scrape the metrics from Platformatic:

global:
  scrape_interval: 15s
  scrape_timeout: 10s
  evaluation_interval: 1m
scrape_configs:
  - job_name: 'platformatic'
    scrape_interval: 2s
    metrics_path: /metrics
    scheme: http
    basic_auth:
      username: platformatic
      password: mysecret
    static_configs:
      - targets: ['192.168.69.195:9091']
        labels:
          group: 'platformatic'

We specify a target configuring the IP address and the port where Platformatic is running, and we specify the username and password to use for basic authentication. The metrics path is the one used by Platformatic. The ip address is not a loopback address so this will work even with Prometheus running in docker on the same host (see below), please change it to your host ip.

To test this configuration, we can run Prometheus locally using docker and docker-compose, so please be sure to have both correctly installed. Save the above configuration in a file named ./prometheus/prometheus.yml and create a docker-compose.yml:

version: "3.7"

services:
  prometheus:
    image: prom/prometheus:latest
    volumes:
      - prometheus_data:/prometheus
      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'
    ports:
      - '9090:9090'

volumes:
  prometheus_data: {}

Then run docker-compose up -d and open http://localhost:9090 in your browser. You should see the Prometheus dashboard, and you can also query the metrics, e.g. {group="platformatic"}. See Prometheus docs for more information on querying and metrics.

Grafana Configuration

Let's see how we can configure Grafana to chart some Platformatics metrics from Prometheus. Change the docker-compose.yml to add a grafana service:

version: "3.7"
services:

  prometheus:
    image: prom/prometheus:latest
    volumes:
      - prometheus_data:/prometheus
      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'
    ports:
      - '9090:9090'

  grafana:
    image: grafana/grafana:latest
    volumes:
      - grafana_data:/var/lib/grafana
    environment:
      - GF_SECURITY_ADMIN_PASSWORD=pleasechangeme
    depends_on:
      - prometheus
    ports:
      - '3000:3000'

volumes:
  prometheus_data: {}
  grafana_data: {}

In Grafana, select Configuration -> Data Sources -> Add Data Source, and select Prometheus. In the URL field, specify the URL of the Prometheus server, e.g. http://prometheus:9090 (the name of the service in the docker-compose file), then Save & Test.

Now we can create a dashboard and add panels to it. Select the Prometheus data source, and add queries. You should see the metrics exposed by Platformatic.

It's also possible to import pre-configured dashboards, like this one from Grafana.com.