monitoring

-- Connection statistics
SELECT
  count(*) AS total_connections,
  count(*) FILTER (WHERE state = 'active') AS active,
  count(*) FILTER (WHERE state = 'idle') AS idle,
  count(*) FILTER (WHERE state = 'idle in transaction') AS idle_in_tx,

# Prometheus configuration
global:
  scrape_interval: 15s
  evaluation_interval: 15s
  scrape_timeout: 10s

class HealthController < ApplicationController
  skip_before_action :verify_authenticity_token

  def liveness
    render json: { status: 'ok' }, status: :ok
  end

package com.example.health;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;

class DeliveryObserver
  def self.delivered_email(message)
    new(message).record
  end

  def initialize(message)

package main

import (
	"log"
	"net/http"
	"time"

module HealthCheckable
  extend ActiveSupport::Concern

  CheckResult = Struct.new(:name, :ok, :message, keyword_init: true)

  private

-- Install TimescaleDB extension
CREATE EXTENSION IF NOT EXISTS timescaledb;

-- Create regular table
CREATE TABLE sensor_data (
  time TIMESTAMPTZ NOT NULL,

package com.example.health;

import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;

const withTimeout = (promise, timeoutMs, name) => {
  let timer;
  const timeout = new Promise((_, reject) => {
    timer = setTimeout(
      () => reject(new Error(`check '${name}' timed out after ${timeoutMs}ms`)),
      timeoutMs

import time
from collections import namedtuple

from sqlalchemy import text

CheckResult = namedtuple("CheckResult", ["name", "healthy", "latency_ms", "detail"])