Initila commit

application/application.go

@@ -0,0 +1,112 @@
+// Package application wires configuration, product collectors and the HTTP server together.
+package application
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	log "github.com/sirupsen/logrus"
+	"lostak.dev/shelly-exporter/collector"
+	"lostak.dev/shelly-exporter/configuration"
+	"lostak.dev/shelly-exporter/shelly"
+)
+
+// Application is a configured Shelly exporter HTTP server.
+type Application struct {
+	config   *configuration.Configuration
+	registry *prometheus.Registry
+	server   *http.Server
+}
+
+// New loads a configuration and registers one collector per Shelly device.
+func New(configPath string) (*Application, error) {
+	config, err := configuration.Load(configPath)
+	if err != nil {
+		return nil, err
+	}
+	log.SetLevel(log.AllLevels[config.LogLevel])
+
+	registry := prometheus.NewRegistry()
+	deviceCollectors := make(collector.Group, 0, len(config.Shelly.Devices))
+	for _, device := range config.Shelly.Devices {
+		client, err := shelly.NewClient(
+			device.URL,
+			device.Username,
+			device.Password,
+			time.Duration(config.Shelly.TimeoutSeconds)*time.Second,
+		)
+		if err != nil {
+			return nil, fmt.Errorf("create client for device %q: %w", device.Name, err)
+		}
+
+		deviceCollector, err := collector.NewDeviceCollector(device, client)
+		if err != nil {
+			return nil, fmt.Errorf("configure device %q: %w", device.Name, err)
+		}
+		deviceCollectors = append(deviceCollectors, deviceCollector)
+		log.Infof("Registered %s metrics for Shelly device %q.", device.Product, device.Name)
+	}
+	if err := registry.Register(deviceCollectors); err != nil {
+		return nil, fmt.Errorf("register device metrics: %w", err)
+	}
+
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.HandlerFor(registry, promhttp.HandlerOpts{EnableOpenMetrics: true}))
+	mux.HandleFunc("/-/healthy", func(response http.ResponseWriter, _ *http.Request) {
+		response.WriteHeader(http.StatusOK)
+		_, _ = response.Write([]byte("OK\n"))
+	})
+
+	address := fmt.Sprintf("%s:%d", config.Host, config.Port)
+	return &Application{
+		config:   config,
+		registry: registry,
+		server: &http.Server{
+			Addr:              address,
+			Handler:           mux,
+			ReadHeaderTimeout: 5 * time.Second,
+			ReadTimeout:       15 * time.Second,
+			WriteTimeout:      30 * time.Second,
+			IdleTimeout:       60 * time.Second,
+		},
+	}, nil
+}
+
+// Run serves metrics until the context is cancelled or the server fails.
+func (app *Application) Run(ctx context.Context) error {
+	listener, err := net.Listen("tcp", app.server.Addr)
+	if err != nil {
+		return fmt.Errorf("listen on %s: %w", app.server.Addr, err)
+	}
+
+	serverError := make(chan error, 1)
+	log.Infof("Shelly exporter started on %s.", listener.Addr())
+	go func() {
+		serverError <- app.server.Serve(listener)
+	}()
+
+	select {
+	case err := <-serverError:
+		if errors.Is(err, http.ErrServerClosed) {
+			return nil
+		}
+		return err
+	case <-ctx.Done():
+		shutdownContext, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := app.server.Shutdown(shutdownContext); err != nil {
+			return fmt.Errorf("shut down HTTP server: %w", err)
+		}
+		err = <-serverError
+		if err != nil && !errors.Is(err, http.ErrServerClosed) {
+			return err
+		}
+		return nil
+	}
+}