refactoring: context, types, etc

checks/checks.go

@@ -3,15 +3,10 @@ package checks
 
 import (
 	"reflect"
-	"time"
 
 	"github.com/hyeoncheon/bogo/internal/common"
 )
 
-const (
-	checkSleep = 100 * time.Millisecond
-)
-
 // Checker couples the name and the runner of each checker.
 type Checker struct {
 	name    string
@@ -37,7 +32,6 @@ func StartAll(c common.Context, opts *common.Options, ch chan interface{}) int {
 	n := 0
 
 	for _, x := range common.Plugins(reflect.TypeOf(&Checker{})) {
-		x, _ := x.(common.Plugin)
 		if len(opts.Checkers) > 0 && !common.Contains(opts.Checkers, x.Name()) {
 			logger.Debugf("%v is not on the checker list. skipping...", x.Name())
 			continue //nolint

checks/heartbeat.go

@@ -47,7 +47,6 @@ func heartbeatRunner(c common.Context, opts common.PluginOptions, out chan inter
 				break infinite
 			case <-ticker.C:
 				out <- "heartbeat"
-			case <-time.After(checkSleep):
 			}
 		}
 		logger.Infof("%s checker exited", heartbeatChecker)

checks/ping.go

@@ -71,11 +71,11 @@ func pingRunner(c common.Context, opts common.PluginOptions, out chan interface{
 					m, err := doPing(host, pingInterval)
 					if err != nil {
 						logger.Error(err)
+						// TODO: sending error message?
 
 						break infinite
 					}
 					out <- m
-				case <-time.After(checkSleep):
 				}
 			}
 			logger.Infof("%s checker for %s exited", pingChecker, host)

checks/ping_test.go

@@ -2,6 +2,7 @@ package checks
 
 import (
 	"testing"
+	"time"
 
 	"github.com/hyeoncheon/bogo"
 	"github.com/hyeoncheon/bogo/internal/common"
@@ -90,6 +91,24 @@ func TestPingRunner_EmptyTarget(t *testing.T) {
 	r.ErrorContains(err, "target string should not be empty")
 }
 
+func TestPingRunner_WrongTarget(t *testing.T) {
+	r := require.New(t)
+
+	opts := common.DefaultOptions()
+	c, _ := common.NewDefaultContext(&opts)
+
+	o := common.PluginOptions{
+		"targets":        []string{"badaddress"},
+		"ping_interval":  []string{"100"},
+		"check_interval": []string{"1"},
+	}
+
+	r.NoError(pingRunner(c, o, c.Channel()))
+	time.Sleep(1100 * time.Millisecond)
+
+	c.Cancel()
+}
+
 func TestPingRunner_InvalidOptionValueCheckInterval(t *testing.T) {
 	r := require.New(t)
 

cmd/bogo/main.go

@@ -14,6 +14,7 @@ import (
 	"github.com/hyeoncheon/bogo/checks"
 	"github.com/hyeoncheon/bogo/exporters"
 	"github.com/hyeoncheon/bogo/internal/common"
+	"github.com/hyeoncheon/bogo/internal/defaults"
 	"github.com/hyeoncheon/bogo/meari"
 
 	getopt "github.com/pborman/getopt/v2"
@@ -105,7 +106,8 @@ func run(c common.Context, opts *common.Options) {
 
 	logger.Info("shutting down webserver...")
 
-	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
+	ctx, cancel := context.WithTimeout(context.Background(),
+		defaults.ShutdownTimeoutSec*time.Second)
 	defer cancel()
 
 	if err := server.Shutdown(ctx); err != nil {

exporters/exporters.go

@@ -33,7 +33,6 @@ func StartAll(c common.Context, opts *common.Options, ch chan interface{}) int {
 	n := 0
 
 	for _, x := range common.Plugins(reflect.TypeOf(&Exporter{})) {
-		x, _ := x.(common.Plugin)
 		if len(opts.Exporters) > 0 && !common.Contains(opts.Exporters, x.Name()) {
 			logger.Debugf("%v is not on the exporter list. skipping...", x.Name())
 			continue //nolint

internal/common/gcp.go

@@ -60,7 +60,7 @@ func (m *GCEClient) WhereAmI() string {
 		return GOOGLE
 	}
 
-	return NOWHERE
+	return UNKNOWN
 }
 
 // gceMetaInstanceName is a function pointer to metadata.InstanceName().

internal/common/gcp_test.go

@@ -58,7 +58,7 @@ func TestNewGCEMetaClient_NoGCE(t *testing.T) {
 	// actually this could be separated test but just keep it here
 	m = &GCEClient{Client: nil, logger: nil}
 	res := m.WhereAmI()
-	r.Equal(NOWHERE, res)
+	r.Equal(UNKNOWN, res)
 }
 
 func TestGCEClient_InstanceName(t *testing.T) {

internal/common/meta.go

@@ -1,13 +1,13 @@
 package common
 
 const (
-	// NOWHERE is a kind of "I don't care" from the perspective of a specific
-	// driver. For example, GCE meta client can answer with NOWHERE if they
+	// UNKNOWN is a kind of "I don't know" from the perspective of a specific
+	// driver. For example, GCE meta client can answer with UNKNOWN if they
 	// could not detect as they are on GCE.
-	NOWHERE = "Nowhere"
-	// UNKNOWN has different meaning. For example, if this keyword is used,
-	// it should indicate that the environment is explicitly not supported.
 	UNKNOWN = "Unknown"
+	// NOWHERE has different meaning. For example, if this keyword is used,
+	// it should indicate that the environment is explicitly not supported.
+	NOWHERE = "Nowhere"
 )
 
 // MetaClient is an interface to be implemented for each cloud provider.

internal/common/plugins.go

@@ -30,8 +30,8 @@ type Plugin interface {
 // Plugins returns the plugin list for the given type. All register function
 // of the type which is prefixed with "Register" will executed during the
 // registration.
-func Plugins(t reflect.Type) []interface{} {
-	plugins := [](interface{}){}
+func Plugins(t reflect.Type) []Plugin {
+	plugins := [](Plugin){}
 
 	for i := 0; i < t.NumMethod(); i++ {
 		m := t.Method(i)
@@ -43,7 +43,9 @@ func Plugins(t reflect.Type) []interface{} {
 		y := m.Func.Call([]reflect.Value{reflect.ValueOf(x)})[0].Interface()
 		// fmt.Println("plugin found:", reflect.TypeOf(y), y)
 
-		plugins = append(plugins, y)
+		if plugin, ok := y.(Plugin); ok {
+			plugins = append(plugins, plugin)
+		}
 	}
 
 	return plugins

internal/common/plugins_test.go

@@ -12,17 +12,14 @@ func TestPlugins(t *testing.T) {
 	r := require.New(t)
 
 	plugins := Plugins(reflect.TypeOf(&Plugger{}))
-	r.IsType([]interface{}{}, plugins)
 	r.NotEmpty(plugins)
 	r.Equal(2, len(plugins))
 
-	e1 := plugins[0].(Plugin)
-	r.IsType(&Plugger{}, e1)
+	e1 := plugins[0]
 	r.Equal("dummy", e1.Name())
 	r.Nil(e1.Run(nil, nil, nil))
 
-	e2 := plugins[1].(Plugin)
-	r.IsType(&Plugger{}, e2)
+	e2 := plugins[1]
 	r.Equal("mummy", e2.Name())
 	r.Error(e2.Run(nil, nil, nil))
 }

internal/defaults/defaults.go

@@ -1,5 +1,9 @@
 // Package defaults provides the default values.
 package defaults
 
-// ServerAddress is the default listen address for the webserver.
-const ServerAddress = "127.0.0.1:6090"
+const (
+	// ServerAddress is the default listen address for the webserver.
+	ServerAddress = "127.0.0.1:6090"
+	// ShutdownTimeoutSec is the timeout for webserver shutdown in seconds.
+	ShutdownTimeoutSec = 30
+)

meari/default_server.go

@@ -10,58 +10,55 @@ import (
 	"github.com/labstack/echo/v4/middleware"
 )
 
-// defaultServer is a "echo" based simple webserver that implements the
+// DefaultServer is a "echo" based simple webserver that implements the
 // Server interface.
-type defaultServer struct {
+type DefaultServer struct {
 	*echo.Echo
 	address string
 }
 
-var _ Server = &defaultServer{}
+var _ Server = &DefaultServer{}
 
 // NewDefaultServer initializes an instance of defaultServer, registers
 // the "root" handler, and returns it as a Server. Currently, Server works as
 // a singleton.
-func NewDefaultServer(opts *Options) Server {
-	serverOnce.Do(func() {
-		s := &defaultServer{
-			Echo:    echo.New(),
-			address: defaults.ServerAddress,
-		}
-		s.Echo.HideBanner = true
-		s.Echo.Debug = true
+func NewDefaultServer(opts *Options) *DefaultServer {
+	s := &DefaultServer{
+		Echo:    echo.New(),
+		address: defaults.ServerAddress,
+	}
+	s.Echo.HideBanner = true
+	s.Echo.Debug = true
 
-		if opts.Address != "" {
-			s.address = opts.Address
-		}
+	if opts.Address != "" {
+		s.address = opts.Address
+	}
 
-		s.Echo.Use(middleware.Logger())
+	s.Echo.Use(middleware.Logger())
 
-		s.GET("/", func(c echo.Context) error {
-			return c.String(http.StatusOK, "Hey, Bulldog!")
-		})
-		server = s
+	s.GET("/", func(c echo.Context) error {
+		return c.String(http.StatusOK, "Hey, Bulldog!")
 	})
 
-	return server
+	return s
 }
 
 // Address implements the Server interface.
-func (s *defaultServer) Address() string {
+func (s *DefaultServer) Address() string {
 	return s.address
 }
 
 // Serve implements the Server interface.
-func (s *defaultServer) Serve() error {
+func (s *DefaultServer) Serve() error {
 	return s.Echo.Start(s.address)
 }
 
 // Shutdown implements the Server interface.
-func (s *defaultServer) Shutdown(c context.Context) error {
+func (s *DefaultServer) Shutdown(c context.Context) error {
 	return s.Echo.Shutdown(c)
 }
 
 // GET implements the Server interface.
-func (s *defaultServer) GET(path string, handler echo.HandlerFunc) {
+func (s *DefaultServer) GET(path string, handler echo.HandlerFunc) {
 	s.Echo.GET(path, handler)
 }

meari/default_server_test.go

@@ -2,37 +2,28 @@ package meari
 
 import (
 	"net/http"
-	"sync"
 	"testing"
 	"time"
 
 	"github.com/hyeoncheon/bogo/internal/defaults"
+
 	"github.com/stretchr/testify/require"
 	"golang.org/x/net/context"
 )
 
-// TestNewDefaultServer tests the generator and if the singleton works fine.
+// TestNewDefaultServer tests the NewDefaultServer function.
 func TestNewDefaultServer(t *testing.T) {
 	r := require.New(t)
 
-	s1 := NewDefaultServer(&Options{})
-	r.NotNil(s1)
-
 	s := NewDefaultServer(&Options{})
 	r.NotNil(s)
-	r.Equal(s1, s) // singleton by Once
 	r.Equal(defaults.ServerAddress, s.Address())
-
-	r.Nil(nil)
 }
 
 // TestNewDefaultServer_Address tests if Options.Address is working.
 func TestNewDefaultServer_Address(t *testing.T) {
 	r := require.New(t)
 
-	serverOnce = sync.Once{}
-	server = nil
-
 	s := NewDefaultServer(&Options{Address: ":80"})
 	r.NotNil(s)
 	r.Equal(":80", s.Address())
@@ -45,9 +36,6 @@ func TestDefaultServer_Functions(t *testing.T) {
 	r := require.New(t)
 	r.Nil(nil)
 
-	serverOnce = sync.Once{}
-	server = nil
-
 	s := NewDefaultServer(&Options{})
 	r.NotNil(s)
 	r.Equal(defaults.ServerAddress, s.Address())

meari/server.go

@@ -21,6 +21,7 @@ var errUnsupportedMethod = errors.New("unsupported method")
 var (
 	serverOnce sync.Once
 	server     Server
+	serverErr  error // nolint
 )
 
 // Options is a basic structure that contains all options for the Server
@@ -55,17 +56,20 @@ func NewServer(c common.Context, opts *common.Options) (Server, error) {
 		Address: opts.Address,
 	}
 
-	server := NewDefaultServer(serverOpts)
+	serverOnce.Do(func() {
+		server = NewDefaultServer(serverOpts)
+		serverErr = nil
 
-	for p, handler := range handlers.AllHandlers() {
-		switch handler.Method {
-		case http.MethodGet:
-			logger.Debugf("register handler for 'GET %v'...", p)
-			server.GET(p, handler.Handler)
-		default:
-			return nil, fmt.Errorf("%w: %v", errUnsupportedMethod, handler)
+		for p, handler := range handlers.AllHandlers() {
+			switch handler.Method {
+			case http.MethodGet:
+				logger.Debugf("register handler for 'GET %v'...", p)
+				server.GET(p, handler.Handler)
+			default:
+				serverErr = fmt.Errorf("%w: %v", errUnsupportedMethod, handler)
+			}
 		}
-	}
+	})
 
-	return server, nil
+	return server, serverErr
 }