Use golangci-lint as linter (#29)

* Use golangci-lint as linter

This is faster than `goimports` and includes more linters.

Also removed non user-runnable targets from Makefile.

Finally, applied changes to the code to comply with the code.

.golangci.yaml

@@ -0,0 +1,109 @@
+run:
+  # timeout for analysis, e.g. 30s, 5m, default is 1m
+  timeout: 1m
+
+  # include test files or not, default is true
+  tests: true
+
+  # list of build tags, all linters use it. Default is empty list.
+  build-tags: []
+
+# settings of specific linters
+linters-settings:
+  govet:
+    check-shadowing: false
+  golint:
+    min-confidence: 0
+  maligned:
+    suggest-new: true
+  dupl:
+    threshold: 100
+  goconst:
+    min-len: 2
+    min-occurrences: 2
+  misspell:
+    locale: US
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - experimental
+      - opinionated
+      - style
+    disabled-checks:
+      - dupImport # https://github.com/go-critic/go-critic/issues/845
+      - ifElseChain
+      - octalLiteral
+      - wrapperFunc
+
+linters:
+  disable-all: true
+  enable:
+    - bodyclose
+    - deadcode
+    - depguard
+    - dogsled
+    - dupl
+    - errcheck
+    - goconst
+    - gocritic
+    - gofmt
+    - goimports
+    - golint
+    - gosec
+    - gosimple
+    - govet
+    - ineffassign
+    - interfacer
+    - misspell
+    - nakedret
+    - scopelint
+    - staticcheck
+    - structcheck
+    - stylecheck
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - varcheck
+    - whitespace
+
+  # don't enable:
+  # - funlen
+  # - gochecknoglobals
+  # - gocognit
+  # - gocyclo
+  # - godox
+  # - lll
+  # - maligned
+  # - prealloc
+  # - gochecknoinits
+
+
+issues:
+  # Excluding configuration per-path, per-linter, per-text and per-source
+  exclude-rules:
+    # Exclude some linters from running on tests files.
+    - path: _test\.go
+      linters:
+        - gocyclo
+        - errcheck
+        - dupl
+        - gosec
+        - scopelint
+        - goconst
+        - funlen
+        - gocritic
+
+  # Maximum issues count per one linter. Set to 0 to disable. Default is 50.
+  max-issues-per-linter: 0
+
+  # Maximum count of issues with the same text. Set to 0 to disable. Default is 3.
+  max-same-issues: 0
+
+  # Show only new issues: if there are unstaged changes or untracked files,
+  # only those changes are analyzed, else only changes in HEAD~ are analyzed.
+  # It's a super-useful option for integration of golangci-lint into existing
+  # large codebase. It's not practical to fix all existing issues at the moment
+  # of integration: much better don't allow issues in new code.
+  # Default is false.
+  new: false

.travis.yml

@@ -1,18 +1,19 @@
 language: go
 
 go:
-  - "1.11.x"
   - "1.12.x"
+  - "1.13.x"
 
 env:
   - GO111MODULE=on
 
 install:
-  - make install
+  - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.20.1
 
 script:
   - make test
-  - make check-fmt
+  - make lint 
 
 after_success:
-  - make report-coveralls
+  - go get github.com/mattn/goveralls
+  - goveralls -coverprofile=coverage.out -service=travis-ci

Makefile

@@ -1,25 +1,16 @@
-.PHONY: test benchmark help fmt install
+.PHONY: test help fmt report-coveralls benchmark lint
 
 help: ## Show the help text
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "    \033[36m%-20s\033[93m %s\n", $$1, $$2}'
 
 test: ## Run unit tests
 	@go test -coverprofile=coverage.out -covermode=atomic -race ./...
 
-benchmark: ## Run benchmarks
-	@go test -bench=. ./...
-
-check-fmt: ## Check file forma
-	@GOIMP=$$(for f in $$(find . -type f -name "*.go" ! -path "./.cache/*" ! -path "./vendor/*" ! -name "bindata.go") ; do \
-		goimports -l $$f ; \
-	done) && echo $$GOIMP && test -z "$$GOIMP"
+lint: # Run linters using golangci-lint 
+	@golangci-lint run
 
 fmt: ## Format files
 	@goimports -w $$(find . -name "*.go" -not -path "./vendor/*")
 
-install: ## Installs dependencies
-	GOPATH=$$GOPATH && go get -u -v \
-		golang.org/x/tools/cmd/goimports
-
-report-coveralls: ## Reports generated coverage profile to coveralls.io. Intended to be used only from travis
-	go get github.com/mattn/goveralls && goveralls -coverprofile=coverage.out -service=travis-ci
+benchmark: ## Run benchmarks
+	@go test -run=NONE -benchmem -benchtime=5s -bench=. ./...	

default.go

@@ -27,12 +27,12 @@ func AddBuilder(typ reflect.Type, registerer Builder) error {
 	return DefaultInitializer.AddBuilder(typ, registerer)
 }
 
-// MustInit initialises the metrics or panics.
+// MustInit initializes the metrics or panics.
 func MustInit(metrics interface{}, namespace string) {
 	DefaultInitializer.MustInit(metrics, namespace)
 }
 
-// Init initialises the metrics in the given namespace.
+// Init initializes the metrics in the given namespace.
 func Init(metrics interface{}, namespace string) error {
 	return DefaultInitializer.Init(metrics, namespace)
 }

init.go

@@ -28,10 +28,10 @@ type Initializer interface {
 	// func() interface{} implements <typ>
 	AddBuilder(typ reflect.Type, registerer Builder) error
 
-	// MustInit initialises the metrics or panics.
+	// MustInit initializes the metrics or panics.
 	MustInit(metrics interface{}, namespace string)
 
-	// Init initialises the metrics in the given namespace.
+	// Init initializes the metrics in the given namespace.
 	Init(metrics interface{}, namespace string) error
 }
 
@@ -68,14 +68,14 @@ func (in initializer) AddBuilder(typ reflect.Type, builder Builder) error {
 	return nil
 }
 
-// MustInit initialises the metrics or panics.
+// MustInit initializes the metrics or panics.
 func (in initializer) MustInit(metrics interface{}, namespace string) {
 	if err := in.Init(metrics, namespace); err != nil {
 		panic(err)
 	}
 }
 
-// Init initialises the metrics in the given namespace.
+// Init initializes the metrics in the given namespace.
 func (in initializer) Init(metrics interface{}, namespace string) error {
 	metricsPtr := reflect.ValueOf(metrics)
 	if metricsPtr.Kind() != reflect.Ptr {
@@ -91,7 +91,6 @@ func (in initializer) initMetrics(group reflect.Value, namespaces ...string) err
 	}
 
 	for i := 0; i < group.Type().NumField(); i++ {
-
 		field := group.Field(i)
 		fieldType := group.Type().Field(i)
 
@@ -177,7 +176,6 @@ func (in initializer) initMetricFunc(field reflect.Value, structField reflect.St
 	metricFunc := func(args []reflect.Value) []reflect.Value {
 		labels := make(prometheus.Labels, len(labelIndexes))
 		for label, index := range labelIndexes {
-
 			value := args[0].FieldByIndex(index)
 
 			if label.hasDefaultValue && value.Interface() == label.zeroTypeValueInterface {
@@ -227,7 +225,6 @@ func findLabelIndexes(typ reflect.Type, indexes map[label][]int, current ...int)
 				return err
 			}
 		} else {
-
 			labelTag, ok := f.Tag.Lookup("label")
 			if !ok {
 				return fmt.Errorf("field %s does not have the label tag", f.Name)

metrics_test.go

@@ -82,9 +82,9 @@ func Test_NestedMetrics(t *testing.T) {
 	}
 
 	assert.Equal(t, map[string]struct{}{
-		"testservice_server_hits_total":        struct{}{},
-		"testservice_client_requests_total":    struct{}{},
-		"testservice_memory_consumption_bytes": struct{}{},
+		"testservice_server_hits_total":        {},
+		"testservice_client_requests_total":    {},
+		"testservice_memory_consumption_bytes": {},
 	}, reportedMetrics)
 }
 

prometheusvanilla/builders.go

@@ -119,7 +119,7 @@ func bucketsFromTag(tag reflect.StructTag) ([]float64, error) {
 		return nil, fmt.Errorf("buckets not specified")
 	}
 
-	if len(bucketsString) == 0 {
+	if bucketsString == "" {
 		return nil, nil
 	}
 
@@ -160,7 +160,7 @@ func objectivesFromTag(tag reflect.StructTag) (map[float64]float64, error) {
 		return nil, fmt.Errorf("objectives not specified")
 	}
 
-	if len(quantileString) == 0 {
+	if quantileString == "" {
 		return nil, nil
 	}