Simple implementation of the health checker for the worker

Gopkg.lock

@@ -39,6 +39,14 @@
   revision = "346938d642f2ec3594ed81d874461961cd0faa76"
   version = "v1.1.0"
 
+[[projects]]
+  digest = "1:2e7c296138d042515eb2995fe58026eaef2c08f660a5f36584faecf34eea3cf0"
+  name = "github.com/etherlabsio/healthcheck"
+  packages = ["."]
+  pruneopts = ""
+  revision = "dd3d2fd8c3f620a32b7f3cd9b4f0d2f7d0875ab1"
+  version = "2.0.3"
+
 [[projects]]
   digest = "1:9f1e571696860f2b4f8a241b43ce91c6085e7aaed849ccca53f590a4dc7b95bd"
   name = "github.com/fsnotify/fsnotify"
@@ -311,6 +319,7 @@
     "github.com/SermoDigital/jose/crypto",
     "github.com/SermoDigital/jose/jws",
     "github.com/asaskevich/EventBus",
+    "github.com/etherlabsio/healthcheck",
     "github.com/getsentry/raven-go",
     "github.com/gorilla/mux",
     "github.com/h2non/gock",

Gopkg.toml

@@ -41,6 +41,10 @@ ignored = ["github.com/elyby/chrly"]
   source = "https://github.com/erickskrauch/EventBus.git"
   branch = "publish_nil_values"
 
+[[constraint]]
+  name = "github.com/etherlabsio/healthcheck"
+  version = "2.0.3"
+
 # Testing dependencies
 
 [[constraint]]

cmd/worker.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"os"
 
+	"github.com/etherlabsio/healthcheck"
 	"github.com/mono83/slf/wd"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
@@ -51,6 +52,12 @@ var workerCmd = &cobra.Command{
 			Emitter:       dispatcher,
 			UUIDsProvider: uuidsProvider,
 		}).CreateHandler()
+		handler.Handle("/healthcheck", healthcheck.Handler(
+			healthcheck.WithChecker(
+				"mojang-batch-uuids-provider-response",
+				eventsubscribers.MojangBatchUuidsProviderChecker(dispatcher),
+			),
+		)).Methods("GET")
 
 		finishChan := make(chan bool)
 		go func() {

eventsubscribers/health_checkers.go

@@ -0,0 +1,30 @@
+package eventsubscribers
+
+import (
+	"context"
+	"sync"
+
+	"github.com/etherlabsio/healthcheck"
+
+	"github.com/elyby/chrly/api/mojang"
+)
+
+func MojangBatchUuidsProviderChecker(dispatcher Subscriber) healthcheck.CheckerFunc {
+	var mutex sync.Mutex
+	var lastCallErr error // TODO: need to reset this value after some time
+	dispatcher.Subscribe(
+		"mojang_textures:batch_uuids_provider:result",
+		func(usernames []string, profiles []*mojang.ProfileInfo, err error) {
+			mutex.Lock()
+			lastCallErr = err
+			mutex.Unlock()
+		},
+	)
+
+	return func(ctx context.Context) error {
+		mutex.Lock()
+		defer mutex.Unlock()
+
+		return lastCallErr
+	}
+}

eventsubscribers/health_checkers_test.go

@@ -0,0 +1,35 @@
+package eventsubscribers
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/elyby/chrly/api/mojang"
+	"github.com/elyby/chrly/bootstrap"
+)
+
+func TestMojangBatchUuidsProviderChecker(t *testing.T) {
+	t.Run("empty state", func(t *testing.T) {
+		dispatcher := bootstrap.CreateEventDispatcher()
+		checker := MojangBatchUuidsProviderChecker(dispatcher)
+		assert.Nil(t, checker(context.Background()))
+	})
+
+	t.Run("when no error occurred", func(t *testing.T) {
+		dispatcher := bootstrap.CreateEventDispatcher()
+		checker := MojangBatchUuidsProviderChecker(dispatcher)
+		dispatcher.Emit("mojang_textures:batch_uuids_provider:result", []string{"username"}, []*mojang.ProfileInfo{}, nil)
+		assert.Nil(t, checker(context.Background()))
+	})
+
+	t.Run("when error occurred", func(t *testing.T) {
+		dispatcher := bootstrap.CreateEventDispatcher()
+		checker := MojangBatchUuidsProviderChecker(dispatcher)
+		err := errors.New("some error occurred")
+		dispatcher.Emit("mojang_textures:batch_uuids_provider:result", []string{"username"}, nil, err)
+		assert.Equal(t, err, checker(context.Background()))
+	})
+}