solidate error handling and return checking

checks/checks.go

@@ -29,11 +29,12 @@ func (p *Checker) Run(c common.Context, opts common.PluginOptions, ch chan inter
 	return p.runFunc(c, opts, ch)
 }
 
-func StartAll(c common.Context, opts *common.Options, ch chan interface{}) {
+func StartAll(c common.Context, opts *common.Options, ch chan interface{}) int {
 	logger := c.Logger().WithField("module", "checker")
+	n := 0
 
 	for _, x := range common.Plugins(reflect.TypeOf(&Checker{})) {
-		x := x.(common.Plugin)
+		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
@@ -44,6 +45,9 @@ func StartAll(c common.Context, opts *common.Options, ch chan interface{}) {
 		if err := x.Run(c, copts, ch); err != nil {
 			logger.Errorf("%s checker was aborted: %v", x.Name(), err)
 			// TODO: should returns error?
+		} else {
+			n++
 		}
 	}
+	return n
 }

checks/checks_test.go

@@ -21,7 +21,8 @@ func TestStartAll(t *testing.T) {
 	ctx, _ := common.NewDefaultContext(&opts)
 	defer ctx.Cancel()
 
-	StartAll(ctx, &opts, ctx.Channel())
+	n := StartAll(ctx, &opts, ctx.Channel())
+	r.Equal(1, n)
 
 	out := <-ctx.Channel()
 	r.NotNil(out)
@@ -41,6 +42,8 @@ func TestStartAll_Error(t *testing.T) {
 	ctx, _ := common.NewDefaultContext(&opts)
 	defer ctx.Cancel()
 
-	StartAll(ctx, &opts, ctx.Channel())
+	n := StartAll(ctx, &opts, ctx.Channel())
+	r.Equal(0, n)
+
 	r.Equal("--- &{{} [0 0 0]}", fmt.Sprintf("--- %v", ctx.WG()))
 }

checks/heartbeat.go

@@ -1,7 +1,7 @@
 package checks
 
 import (
-	"errors"
+	"fmt"
 	"time"
 
 	"github.com/hyeoncheon/bogo/internal/common"
@@ -24,7 +24,7 @@ func heartbeatRunner(c common.Context, opts common.PluginOptions, out chan inter
 
 	interval, err := opts.GetIntegerOr("interval", heartbeatCheckerIntervalSec)
 	if err != nil {
-		return errors.New("invalid option value: interval")
+		return fmt.Errorf("%w: interval", common.ErrInvalidOptionValue)
 	}
 
 	c.WG().Add(1)

checks/ping.go

@@ -1,6 +1,7 @@
 package checks
 
 import (
+	"errors"
 	"fmt"
 	"time"
 
@@ -17,6 +18,11 @@ const (
 	pingCount              = 10
 )
 
+var (
+	errNoTargetsSpecified           = errors.New("no targets specified")
+	errTargetStringShouldNotBeEmpty = errors.New("target string should not be empty")
+)
+
 func (*Checker) RegisterPing() *Checker {
 	return &Checker{
 		name:    pingChecker,
@@ -35,12 +41,12 @@ func pingRunner(c common.Context, opts common.PluginOptions, out chan interface{
 
 	checkInterval, err := opts.GetIntegerOr("check_interval", pingCheckerIntervalSec)
 	if err != nil {
-		return fmt.Errorf("invalid option value: check_interval")
+		return fmt.Errorf("%w: check_interval", common.ErrInvalidOptionValue)
 	}
 
 	pingInterval, err := opts.GetIntegerOr("ping_interval", pingIntervalMilliSec)
 	if err != nil {
-		return fmt.Errorf("invalid option value: check_interval")
+		return fmt.Errorf("%w: check_interval", common.ErrInvalidOptionValue)
 	}
 
 	// spawn ping workers for each target
@@ -82,12 +88,12 @@ func getTarget(c common.Context, opts *common.PluginOptions) ([]string, error) {
 	}
 
 	if len(targets) < 1 {
-		return targets, fmt.Errorf("no targets specified")
+		return targets, errNoTargetsSpecified
 	}
 
 	for _, t := range targets {
 		if len(t) < 1 {
-			return targets, fmt.Errorf("target string should not be empty: %v", targets)
+			return targets, fmt.Errorf("%w: %v", errTargetStringShouldNotBeEmpty, targets)
 		}
 	}
 

cmd/bogo/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"os"
@@ -81,8 +82,9 @@ func run(c common.Context, opts *common.Options) {
 		}
 	}()
 
-	checks.StartAll(c, opts, c.Channel())
-	exporters.StartAll(c, opts, c.Channel())
+	cn := checks.StartAll(c, opts, c.Channel())
+	en := exporters.StartAll(c, opts, c.Channel())
+	logger.Infof("%d checkers and %d exporters started", cn, en)
 
 	server, err := startWebRoutine(c, opts)
 	if err != nil {
@@ -118,7 +120,7 @@ func startWebRoutine(c common.Context, opts *common.Options) (meari.Server, erro
 		defer c.WG().Done()
 
 		err := server.Start()
-		if err == http.ErrServerClosed {
+		if errors.Is(err, http.ErrServerClosed) {
 			logger.Info("webserver closed")
 		} else {
 			logger.Error("unexpected error: ", err)

cmd/bogo/main_test.go

@@ -30,9 +30,9 @@ func TestRun(t *testing.T) {
 	}()
 
 	time.Sleep(1 * time.Second)
-	syscall.Kill(syscall.Getpid(), syscall.SIGUSR1)
+	_ = syscall.Kill(syscall.Getpid(), syscall.SIGUSR1)
 
-	syscall.Kill(syscall.Getpid(), syscall.SIGINT)
+	_ = syscall.Kill(syscall.Getpid(), syscall.SIGINT)
 	wg.Wait()
 	r.True(indicator)
 }

exporters/exporters.go

@@ -24,11 +24,12 @@ func (p *Exporter) Run(c common.Context, opts common.PluginOptions, ch chan inte
 	return p.runFunc(c, opts, ch)
 }
 
-func StartAll(c common.Context, opts *common.Options, ch chan interface{}) {
+func StartAll(c common.Context, opts *common.Options, ch chan interface{}) int {
 	logger := c.Logger().WithField("module", "exporter")
+	n := 0
 
 	for _, x := range common.Plugins(reflect.TypeOf(&Exporter{})) {
-		x := x.(common.Plugin)
+		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
@@ -39,6 +40,9 @@ func StartAll(c common.Context, opts *common.Options, ch chan interface{}) {
 		if err := x.Run(c, eopts, ch); err != nil {
 			logger.Errorf("%s exporter was aborted: %v", x.Name(), err)
 			// TODO: should returns error?
+		} else {
+			n++
 		}
 	}
+	return n
 }

exporters/exporters_test.go

@@ -4,9 +4,12 @@ import (
 	"testing"
 
 	"github.com/hyeoncheon/bogo/internal/common"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestStartAll(t *testing.T) {
+	r := require.New(t)
 	opts := common.DefaultOptions()
 	opts.Exporters = []string{"stdout"}
 	opts.ExporterOptions = map[string]common.PluginOptions{
@@ -16,7 +19,8 @@ func TestStartAll(t *testing.T) {
 	}
 	ctx, _ := common.NewDefaultContext(&opts)
 
-	StartAll(ctx, &opts, ctx.Channel())
+	n := StartAll(ctx, &opts, ctx.Channel())
+	r.Equal(1, n)
 
 	ctx.Channel() <- "message"
 

exporters/stackdriver.go

@@ -47,7 +47,7 @@ func stackdriverRunner(c common.Context, _ common.PluginOptions, in chan interfa
 	}
 
 	if err := registerViews(); err != nil {
-		return fmt.Errorf("could not register views: %v", err)
+		return fmt.Errorf("could not register views: %w", err)
 	}
 
 	exporter, err := createAndStartExporter()
@@ -77,7 +77,7 @@ func stackdriverRunner(c common.Context, _ common.PluginOptions, in chan interfa
 				if pm, ok := m.(bogo.PingMessage); ok {
 					logger.Debugf("ping: %v", pm)
 					if err := recordPingMessage(r, &pm); err != nil {
-						logger.Errorf("message %v: %v", pm, err)
+						logger.Errorf("message %v: %w", pm, err)
 					}
 				} else {
 					logger.Warnf("unknown: %v", m)
@@ -95,7 +95,7 @@ func getReporter(c common.Context) (*reporter, error) {
 	// currently, stackdriver exporter is only suppored on the GCE instance
 	meta := c.Meta()
 	if meta == nil || meta.WhereAmI() != "Google" {
-		return nil, fmt.Errorf("not on the Google Compute Engine")
+		return nil, common.ErrorNotOnGCE
 	}
 
 	return &reporter{
@@ -146,11 +146,11 @@ func createAndStartExporter() (*stackdriver.Exporter, error) {
 		},
 	})
 	if err != nil {
-		return nil, fmt.Errorf("could not create exporter: %v", err)
+		return nil, fmt.Errorf("could not create exporter: %w", err)
 	}
 
 	if err := exporter.StartMetricsExporter(); err != nil {
-		return nil, fmt.Errorf("could not start metric exporter: %v", err)
+		return nil, fmt.Errorf("could not start metric exporter: %w", err)
 	}
 	return exporter, nil
 }
@@ -166,7 +166,7 @@ func recordPingMessage(r *reporter, m *bogo.PingMessage) error {
 		avgRttMs.M(float64(m.AvgRtt.Milliseconds())),
 		lossRate.M(m.Loss),
 	); err != nil {
-		return fmt.Errorf("could not send ping stat: %v", err)
+		return fmt.Errorf("could not send ping stat: %w", err)
 	}
 	return nil
 }

internal/common/gcp.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"errors"
 	"net/http"
 	"strings"
 	"sync"
@@ -12,6 +13,8 @@ import (
 
 const GOOGLE = "Google"
 
+var ErrorNotOnGCE = errors.New("not on the Google Compute Engine")
+
 // asset GCEClient for MetaClient iplemetations
 var _ MetaClient = &GCEClient{}
 

internal/common/gcp_test.go

@@ -254,7 +254,7 @@ func TestGCEClient_RoundTrip(t *testing.T) {
 
 	server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
 		ua := req.Header.Get("User-Agent")
-		rw.Write([]byte(ua))
+		_, _ = rw.Write([]byte(ua))
 	}))
 	defer server.Close()
 

internal/common/plugins.go

@@ -1,12 +1,18 @@
 package common
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"strconv"
 	"strings"
 )
 
+var (
+	ErrInvalidePluginOption = errors.New("invalid plugin option")
+	ErrInvalidOptionValue   = errors.New("invalid option value")
+)
+
 type Plugin interface {
 	Name() string
 	Run(Context, PluginOptions, chan interface{}) error
@@ -59,7 +65,7 @@ func BuildPluginOptions(s string) (map[string]PluginOptions, error) {
 					options[t[0]] = PluginOptions{t[1]: StringValues(t[2])}
 				}
 			} else {
-				return nil, fmt.Errorf("invalid plugin option '%v'", e)
+				return nil, fmt.Errorf("%w: %v", ErrInvalidePluginOption, e)
 			}
 		}
 	}

internal/common/plugins_test.go

@@ -1,7 +1,7 @@
 package common
 
 import (
-	"errors"
+	"fmt"
 	"reflect"
 	"testing"
 
@@ -63,12 +63,12 @@ func TestBuildPluginOptions(t *testing.T) {
 		{
 			in:  "heartbeat:interval",
 			out: nil,
-			e:   errors.New("invalid plugin option 'heartbeat:interval'"),
+			e:   fmt.Errorf("%w: heartbeat:interval", ErrInvalidePluginOption),
 		},
 		{
 			in:  "heartbeat",
 			out: nil,
-			e:   errors.New("invalid plugin option 'heartbeat'"),
+			e:   fmt.Errorf("%w: heartbeat", ErrInvalidePluginOption),
 		},
 	}
 

makefile

@@ -1,8 +1,13 @@
 
+LINTERS			= gocognit,gocyclo,misspell
+MORE_LINTERS		= errorlint,goerr113,forcetypeassert
+DISABLED_LINTERS	= godot,godox,wsl,varnamelen,nlreturn,testpackage,paralleltest,wrapcheck,exhaustivestruct,gci,gochecknoglobals
+
 default: test lint
 
 lint:
-	golangci-lint run -E gocognit,gocyclo,misspell --tests=false
+	golangci-lint run -E $(LINTERS)
+	golangci-lint run -E $(LINTERS),$(MORE_LINTERS) --tests=false
 
 test:
 	go test -race -coverprofile=coverage.txt -covermode=atomic ./...

meari/server.go

@@ -2,6 +2,7 @@ package meari
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 
@@ -11,6 +12,11 @@ import (
 	"github.com/hyeoncheon/bogo/internal/common"
 )
 
+var (
+	errorCouldNotInitiate  = errors.New("could not initiate the web server")
+	errorUnsupportedMethod = errors.New("unsupported method")
+)
+
 type Options struct {
 	Logger  common.Logger
 	Address string
@@ -32,7 +38,7 @@ func NewServer(c common.Context, opts *common.Options) (Server, error) {
 	}
 	server := NewDefaultServer(serverOpts)
 	if server == nil {
-		return nil, fmt.Errorf("could not initiate the web server: %v", serverOpts)
+		return nil, fmt.Errorf("%w: %v", errorCouldNotInitiate, serverOpts)
 	}
 
 	for p, handler := range handlers.AllHandlers() {
@@ -41,7 +47,7 @@ func NewServer(c common.Context, opts *common.Options) (Server, error) {
 			logger.Debugf("register handler for 'GET %v'...", p)
 			server.GET(p, handler.Handler)
 		default:
-			return nil, fmt.Errorf("unsupported method for %v", handler)
+			return nil, fmt.Errorf("%w: %v", errorUnsupportedMethod, handler)
 		}
 	}