Rethink how metricator will work, golangci-lint and gitlab ci configs.

internal/application/application.go

@@ -0,0 +1,63 @@
+package application
+
+import (
+	"context"
+	"log"
+
+	"go.dev.pztrn.name/metricator/internal/storage"
+	"go.dev.pztrn.name/metricator/internal/storage/memory"
+)
+
+// Application is a thing that responsible for all application-related
+// actions like data fetching, storing, etc. on higher level.
+type Application struct {
+	config   *Config
+	ctx      context.Context
+	doneChan chan struct{}
+	name     string
+
+	storage     storage.Metrics
+	storageDone chan struct{}
+}
+
+// NewApplication creates new application.
+func NewApplication(ctx context.Context, name string, config *Config) *Application {
+	a := &Application{
+		config:   config,
+		ctx:      ctx,
+		doneChan: make(chan struct{}),
+		name:     name,
+	}
+	a.initialize()
+
+	return a
+}
+
+// GetDoneChan returns a channel which should be used to block execution until
+// application's routines are completed.
+func (a *Application) GetDoneChan() chan struct{} {
+	return a.doneChan
+}
+
+// Initializes internal things like storage, HTTP client, etc.
+func (a *Application) initialize() {
+	a.storage, a.storageDone = memory.NewStorage(a.ctx, a.name+" storage")
+
+	log.Printf("Application '%s' initialized with configuration: %+v\n", a.name, a.config)
+}
+
+// Start starts asynchronous things like data fetching, storage cleanup, etc.
+func (a *Application) Start() {
+	a.storage.Start()
+
+	// The Context Listening Goroutine.
+	go func() {
+		<-a.ctx.Done()
+		// We should wait until storage routines are also stopped.
+		<-a.storage.GetDoneChan()
+
+		log.Println("Application", a.name, "stopped")
+
+		a.doneChan <- struct{}{}
+	}()
+}

internal/application/config.go

@@ -0,0 +1,15 @@
+package application
+
+import "time"
+
+// Config is a generic application configuration.
+type Config struct {
+	// Endpoint is a remote application endpoint which should give us metrics
+	// in Prometheus format.
+	Endpoint string
+	// Headers is a list of headers that should be added to metrics request.
+	Headers map[string]string
+	// TimeBetweenRequests is a minimal amount of time which should pass
+	// between requests.
+	TimeBetweenRequests time.Duration
+}

internal/application/fetcher.go

@@ -0,0 +1,4 @@
+package application
+
+// Configures and starts Prometheus data fetching goroutine.
+func (a *Application) startFetcher() {}