event-gateway/main.go

// Copyright © 2023 Roberto Hidalgo <event-gateway@un.rob.mx>
// SPDX-License-Identifier: Apache-2.0
package main

import (
	"fmt"
	"log"
	"net/http"
	"os"

	"git.rob.mx/nidito/chinampa"
	"git.rob.mx/nidito/chinampa/pkg/command"
	"git.rob.mx/nidito/chinampa/pkg/env"
	"git.rob.mx/nidito/chinampa/pkg/logger"
	"git.rob.mx/nidito/chinampa/pkg/runtime"
	"git.rob.mx/nidito/event-gateway/internal/config"
	"git.rob.mx/nidito/event-gateway/internal/source"
	"git.rob.mx/nidito/event-gateway/internal/source/consul"
	httpsrc "git.rob.mx/nidito/event-gateway/internal/source/http"
	"git.rob.mx/nidito/event-gateway/internal/version"
	"github.com/hashicorp/consul/api"
	"github.com/honeycombio/honeycomb-opentelemetry-go"
	"github.com/honeycombio/otel-config-go/otelconfig"
	"github.com/julienschmidt/httprouter"
)

var Server = &command.Command{
	Path:        []string{"server"},
	Summary:     "starts a server",
	Description: "tbd",
	Arguments: command.Arguments{
		&command.Argument{
			Name:        "listen",
			Default:     ":8000",
			Description: "An address for the http server to listen at",
		},
	},
	Options: command.Options{
		"source": &command.Option{
			Type:        command.ValueTypeString,
			Description: "Event sources to enable",
			Repeated:    true,
			Default:     []string{"http"},
			Values: &command.ValueSource{
				Static: &[]string{
					"http",
					"consul",
				},
			},
		},
		"sink": &command.Option{
			Type:        command.ValueTypeString,
			Description: "Event sinks to enable",
			Repeated:    true,
			Default:     []string{"debug", "nomad"},
			Values: &command.ValueSource{
				Static: &[]string{
					"debug",
					"nomad",
				},
			},
		},
		"config": &command.Option{
			Type:        command.ValueTypeString,
			Description: "A URL (file:// if no scheme is provided) where to read configuration from",
			Default:     "file://listeners.json",
		},
	},
	Action: func(cmd *command.Command) error {
		router := httprouter.New()
		addr := cmd.Arguments[0].ToString()
		manager := &source.Manager{}

		// Enable multi-span attributes
		bsp := honeycomb.NewBaggageSpanProcessor()
		// Use the Honeycomb distro to set up the OpenTelemetry SDK
		otelShutdown, err := otelconfig.ConfigureOpenTelemetry(
			otelconfig.WithSpanProcessor(bsp),
		)
		if err != nil {
			log.Fatalf("error setting up OTel SDK - %e", err)
		}
		defer otelShutdown()

		for _, source := range cmd.Options["source"].ToValue().([]string) {
			switch source {
			case "http":
				manager.AddSource(&httpsrc.Source{Router: router})
			case "consul":
				cfg := api.DefaultConfig()
				client, err := api.NewClient(cfg)

				if err != nil {
					return fmt.Errorf("could not create consul client: %s", err)
				}
				manager.AddSource(&consul.Source{Client: client.Event()})
			default:
				logger.Fatalf("Unknown source type: %s", source)
			}
			logger.Infof("added source for %s events", source)
		}

		cfg, err := config.FromURN(cmd.Options["config"].ToString())
		if err != nil {
			return fmt.Errorf("could not initialize configuration loader: %s", err)
		}

		if err := manager.Listen(cfg); err != nil {
			return fmt.Errorf("could not start listener: %s", err)
		}

		return http.ListenAndServe(addr, router)
	},
}

func logLevel() logger.Level {
	if os.Getenv(env.Debug) == "trace" {
		return logger.LevelTrace
	} else if runtime.DebugEnabled() {
		return logger.LevelDebug
	}

	return logger.LevelInfo
}

func main() {
	logger.Configure("event-gateway", logLevel())
	chinampa.Register(Server)

	if err := chinampa.Execute(chinampa.Config{
		Name:        "event-gateway",
		Summary:     "routes events to places",
		Description: `Does things TBD`,
		Version:     version.Version,
	}); err != nil {
		logger.Errorf("total failure: %s", err)
		os.Exit(2)
	}
}