pl.allegro.tech.hermes.consumers.server.ConsumerHttpServer Maven / Gradle / Ivy

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Fast and reliable message broker built on top of Kafka.

There is a newer version: 2.8.0

package pl.allegro.tech.hermes.consumers.server;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpServer;
import io.micrometer.prometheus.PrometheusMeterRegistry;
import pl.allegro.tech.hermes.consumers.health.ConsumerMonitor;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.List;

import static jakarta.ws.rs.core.Response.Status.OK;
import static pl.allegro.tech.hermes.consumers.health.Checks.SUBSCRIPTIONS;
import static pl.allegro.tech.hermes.consumers.health.Checks.SUBSCRIPTIONS_COUNT;

public class ConsumerHttpServer {

    private final HttpServer server;

    private static final String STATUS_UP = "{\"status\": \"UP\"}";

    public ConsumerHttpServer(int healthCheckPort, ConsumerMonitor monitor, ObjectMapper mapper,
                              PrometheusMeterRegistry meterRegistry) throws IOException {
        server = createServer(healthCheckPort);
        server.createContext("/status/health",
                (exchange) -> respondWithJson(exchange, STATUS_UP));
        server.createContext("/status/subscriptions",
                (exchange) -> respondWithObject(exchange, mapper, monitor.check(SUBSCRIPTIONS)));
        server.createContext("/status/subscriptionsCount",
                (exchange) -> respondWithObject(exchange, mapper, monitor.check(SUBSCRIPTIONS_COUNT)));
        server.createContext("/status/prometheus",
                (exchange) -> respondWithString(exchange, meterRegistry.scrape()));
    }

    private HttpServer createServer(int port) throws IOException {
        HttpServer httpServer = HttpServer.create(new InetSocketAddress(port), 0);
        httpServer.setExecutor(null);
        return httpServer;
    }

    private static void respondWithObject(HttpExchange httpExchange, ObjectMapper mapper, Object response) throws IOException {
        respondWithJson(httpExchange, mapper.writeValueAsString(response));
    }

    private static void respondWithJson(HttpExchange httpExchange, String response) throws IOException {
        httpExchange.getResponseHeaders().put("Content-Type", List.of("application/json"));
        respondWithString(httpExchange, response);
    }

    private static void respondWithString(HttpExchange httpExchange, String response) throws IOException {
        httpExchange.sendResponseHeaders(OK.getStatusCode(), response.length());
        OutputStream os = httpExchange.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }

    public void start() {
        server.start();
    }

    public void stop() {
        server.stop(0);
    }

    public int getPort() {
        return server.getAddress().getPort();
    }
}