serverctl/main.go

package main

import (
	"context"
	"errors"
	"github.com/dgraph-io/ristretto"
	"github.com/docker/docker/api/types"
	"github.com/docker/docker/client"
	"github.com/eko/gocache/cache"
	"github.com/eko/gocache/store"
	"github.com/gin-gonic/gin"
	"github.com/go-co-op/gocron"
	"github.com/jackc/pgx/v4/pgxpool"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"io/ioutil"
	"net/http"
	"os"
	"time"
)

func setupLogger() *zap.Logger {
	highPriority := zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
		return lvl >= zapcore.ErrorLevel
	})
	lowPriority := zap.LevelEnablerFunc(func(lvl zapcore.Level) bool {
		return lvl < zapcore.ErrorLevel
	})
	fileDebugging := zapcore.AddSync(ioutil.Discard)
	fileErrors := zapcore.AddSync(ioutil.Discard)

	consoleDebugging := zapcore.Lock(os.Stdout)
	consoleErrors := zapcore.Lock(os.Stderr)

	fileEncoder := zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
	consoleEncoder := zapcore.NewConsoleEncoder(zap.NewDevelopmentEncoderConfig())

	core := zapcore.NewTee(
		zapcore.NewCore(fileEncoder, fileErrors, highPriority),
		zapcore.NewCore(consoleEncoder, consoleErrors, highPriority),
		zapcore.NewCore(fileEncoder, fileDebugging, lowPriority),
		zapcore.NewCore(consoleEncoder, consoleDebugging, lowPriority),
	)

	logger := zap.New(core)
	defer logger.Sync()
	return logger
}
func setupApi(l *zap.Logger, cc *cache.Cache) {
	l.Info("Setting up serverctl setupApi (using gin)")

	r := gin.Default()

	r.GET("/containers", func(c *gin.Context) {
		type container struct {
			Name string `json:"name"`
		}
		var msg struct {
			Containers []container `json:"containers"`
		}

		get, err := cc.Get("docker-containers")
		if err != nil {
			c.JSON(http.StatusInternalServerError, gin.H{"message": "could not get containers from container runtime"})
			return
		}

		msg.Containers = []container{}
		for _, cont := range get.([]types.Container) {
			msg.Containers = append(msg.Containers, container{
				Name: cont.Names[0],
			})
		}

		c.JSON(http.StatusOK, msg)
	})

	r.Run(":8080")

}
func setupDocker(l *zap.Logger) *client.Client {
	l.Info("Setting up Docker")
	cli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
	if err != nil {
		panic(err)
	}

	return cli
}
func setupCache(l *zap.Logger) *cache.Cache {
	l.Info("Setting up cache")
	ristrettoCache, err := ristretto.NewCache(&ristretto.Config{
		NumCounters: 1000,
		MaxCost:     100,
		BufferItems: 64,
	})
	if err != nil {
		panic(err)
	}
	ristrettoStore := store.NewRistretto(ristrettoCache, nil)
	cacheManager := cache.New(ristrettoStore)

	return cacheManager
}
func setupCron(l *zap.Logger, cm *cache.Cache, cc *client.Client) {
	l.Info("Setting up job scheduler (cron)")

	s := gocron.NewScheduler(time.UTC)

	s.Every(10).Second().Do(func() {
		l.Debug("getting container list")
		list, err := cc.ContainerList(context.Background(), types.ContainerListOptions{})
		if err != nil {
			l.Warn(err.Error())
			return
		}

		err = cm.Set("docker-containers", list, &store.Options{
			Cost: 2,
		})
		if err != nil {
			l.Warn(err.Error())
			return
		}
	})

	s.StartAsync()
}
func setupDatabase(l *zap.Logger) *pgxpool.Pool {
	l.Info("Setting up database connection")
	dbUrl := os.Getenv("DATABASE_URL")
	if dbUrl == "" {
		panic(errors.New("DATABASE_URL is not set"))
	}
	dbpool, err := pgxpool.Connect(context.Background(), dbUrl)
	if err != nil {
		panic(err)
	}

	var greeting string
	err = dbpool.QueryRow(context.Background(), "select 'Hello, world!'").Scan(&greeting)
	if err != nil {
		panic(err)
	}

	l.Info("Database successfully connected")

	return dbpool
}

func main() {
	logger := setupLogger()
	logger.Info("Starting serverctl")

	cacheM := setupCache(logger)
	containerClient := setupDocker(logger)
	setupCron(logger, cacheM, containerClient)
	dbpool := setupDatabase(logger)

	setupApi(logger, cacheM)
}