Initial version

.gitignore

@@ -0,0 +1,7 @@
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+vendor

.travis.yml

@@ -0,0 +1,18 @@
+language: go
+
+go:
+  - "1.11.x"
+  - "1.12.x"
+
+env:
+  - GO111MODULE=on
+
+install:
+  - make install
+
+script:
+  - make test
+  - make check-fmt
+
+after_success:
+  - make report-coveralls

CHANGELOG.md

@@ -0,0 +1,11 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [1.0.0] - 2019-08-09
+### Changes
+-  Initial version

Makefile

@@ -0,0 +1,22 @@
+.PHONY: test help fmt check-fmt install report-coveralls
+
+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, $$2}'
+
+test: ## Run unit tests
+	@go test -coverprofile=coverage.out -covermode=atomic -race ./...
+
+check-fmt: ## Check file forma
+	@GOIMP=$$(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"
+
+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

README.md

@@ -0,0 +1,23 @@
+# logrusiowriter
+## `io.Writer` implementation using logrus
+
+[![Travis CI build status](https://travis-ci.com/cabify/logrusiowriter.svg?branch=master)](https://travis-ci.com/cabify/logrusiowriter)
+[![Coverage Status](https://coveralls.io/repos/github/cabify/logrusiowriter/badge.svg)](https://coveralls.io/github/cabify/logrusiowriter)
+[![GoDoc](https://godoc.org/github.com/cabify/logrusiowriter?status.svg)](https://godoc.org/github.com/cabify/logrusiowriter)
+
+# Motivation
+
+Many golang libraries use the golang's `log` package to print their logs. This means that if your application
+uses logrus to print structured logging, those packages will print a format that is (probably) incompatible with yours,
+and you may end losing logs in your logs collector because they can't be parsed properly.
+
+# Solution
+
+Print the logs written using `log.Printf` through `logrus`, by setting `log.SetOutput` to an `io.Writer` implementation
+that uses `logrus` as output, i.e.:
+
+```go
+	log.SetOutput(logrusiowriter.New())
+```
+
+See `example_*_test.go` files to find testable examples that serve as documentation.

configs.go

@@ -0,0 +1,67 @@
+package logrusiowriter
+
+import "github.com/sirupsen/logrus"
+
+// Config holds the configuration to be used with WithConfig() configurer
+// This struct is useful to embed into configuration structs parsed with libraries like envconfig
+type Config struct {
+	Level  string        `default:"info"`
+	Fields logrus.Fields `default:"logger:stdlib"`
+}
+
+// WithLogger configures the logger with the one provided
+func WithLogger(logger logrus.FieldLogger) Configurer {
+	return func(w *writer) {
+		w.logger = logger
+	}
+}
+
+// WithLevel configures the level with the one provided
+func WithLevel(lvl logrus.Level) Configurer {
+	return func(w *writer) {
+		w.level = lvl
+	}
+}
+
+// WithFields configures the fields with the ones provided
+func WithFields(fields logrus.Fields) Configurer {
+	return func(w *writer) {
+		w.fields = fields
+	}
+}
+
+// WithConfig creates a configurer from the configuration provided as a struct
+// If it's unable to parse the Level provided as a string, it will invoke the OnLevelParseError function and set the
+// level returned by that function (a default value)
+func WithConfig(cfg Config) Configurer {
+	return func(w *writer) {
+		lvl, err := logrus.ParseLevel(cfg.Level)
+		if err != nil {
+			lvl = OnLevelParseError(err)
+		}
+		w.level = lvl
+		w.fields = cfg.Fields
+	}
+}
+
+// WithConfigInterface creates a configurer from the configuration provided as an interface
+func WithConfigInterface(cfg interface {
+	Level() logrus.Level
+	Fields() logrus.Fields
+	Logger() logrus.FieldLogger
+}) Configurer {
+	return func(w *writer) {
+		w.logger = cfg.Logger()
+		w.level = cfg.Level()
+		w.fields = cfg.Fields()
+	}
+}
+
+// OnLevelParseError will be invoked if logrus is unable to parse the string level provided in the configuration
+// The default behavior is to log it with logrus and return a default Info level,
+// you can change this to log in some other system or to panic
+// Changing this is not thread safe, so it might be a good idea to change it in a init() function
+var OnLevelParseError = func(err error) logrus.Level {
+	logrus.Errorf("Can't parse level: %s", err)
+	return logrus.InfoLevel
+}

configs_test.go

@@ -0,0 +1,54 @@
+package logrusiowriter
+
+import (
+	"testing"
+
+	"github.com/sirupsen/logrus"
+)
+
+func TestWithConfig(t *testing.T) {
+	t.Run("can't parse level, configures info level by default", func(t *testing.T) {
+		expectedLevel := logrus.InfoLevel
+
+		cfg := Config{
+			Level:  "none",
+			Fields: logrus.Fields{},
+		}
+
+		w := New(WithConfig(cfg))
+
+		configuredLevel := w.(*writer).level
+		if configuredLevel != expectedLevel {
+			t.Errorf("Configured level should be %s, but it was %s", expectedLevel, configuredLevel)
+		}
+	})
+
+	t.Run("custom OnLevelParseError", func(t *testing.T) {
+		originalOnLevelParseError := OnLevelParseError
+		defer func() { OnLevelParseError = originalOnLevelParseError }()
+
+		expectedLevel := logrus.WarnLevel
+
+		cfg := Config{
+			Level:  "none",
+			Fields: logrus.Fields{},
+		}
+
+		var providedErr error
+		OnLevelParseError = func(err error) logrus.Level {
+			providedErr = err
+			return expectedLevel
+		}
+
+		w := New(WithConfig(cfg))
+
+		configuredLevel := w.(*writer).level
+		if configuredLevel != expectedLevel {
+			t.Errorf("Configured level should be %s, but it was %s", expectedLevel, configuredLevel)
+		}
+
+		if providedErr == nil {
+			t.Errorf("Error provided to OnLevelParseError should not be nil")
+		}
+	})
+}

example_configs_test.go

@@ -0,0 +1,93 @@
+package logrusiowriter_test
+
+import (
+	"fmt"
+
+	"github.com/cabify/logrusiowriter"
+	"github.com/sirupsen/logrus"
+)
+
+func ExampleWithConfig() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	config := logrusiowriter.Config{
+		Level: "warning",
+		Fields: map[string]interface{}{
+			"config": "struct",
+		},
+	}
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithConfig(config),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!")
+	// Output:
+	// level=warning msg="Hello World!" config=struct
+}
+
+func ExampleWithFields() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithFields(logrus.Fields{
+			"config": "fields",
+			"other":  288,
+		}),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!")
+	// Output:
+	// level=info msg="Hello World!" config=fields other=288
+}
+
+func ExampleWithLevel() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithLevel(logrus.ErrorLevel),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!")
+	// Output:
+	// level=error msg="Hello World!"
+}
+
+func ExampleWithLogger() {
+	logger := logrus.New()
+	removeTimestampAndSetOutputToStdout(logger)
+	logger.SetLevel(logrus.TraceLevel)
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithLogger(logger),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!")
+	// Output:
+	// level=info msg="Hello World!"
+}
+
+func ExampleWithConfigInterface() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	writer := logrusiowriter.New(
+		logrusiowriter.WithConfigInterface(configProvider{}),
+	)
+
+	_, _ = fmt.Fprint(writer, "Hello World!")
+	// Output:
+	// level=trace msg="Hello World!" config=interface
+}
+
+type configProvider struct{}
+
+func (configProvider) Level() logrus.Level { return logrus.TraceLevel }
+
+func (configProvider) Fields() logrus.Fields { return logrus.Fields{"config": "interface"} }
+
+func (configProvider) Logger() logrus.FieldLogger {
+	logger := logrus.New()
+	removeTimestampAndSetOutputToStdout(logger)
+	logger.SetLevel(logrus.TraceLevel)
+	return logger
+}

example_writer_test.go

@@ -0,0 +1,20 @@
+package logrusiowriter_test
+
+import (
+	"log"
+
+	"github.com/cabify/logrusiowriter"
+	"github.com/sirupsen/logrus"
+)
+
+func ExampleNew() {
+	removeTimestampAndSetOutputToStdout(logrus.StandardLogger())
+
+	log.SetOutput(logrusiowriter.New())
+	log.SetFlags(0) // no date on standard logger
+
+	log.Printf("Standard log")
+
+	// Output:
+	// level=info msg="Standard log\n"
+}

go.mod

@@ -0,0 +1,8 @@
+module github.com/cabify/logrusiowriter
+
+go 1.12
+
+require (
+	github.com/sirupsen/logrus v1.4.2
+	golang.org/x/sys v0.0.0-20190804053845-51ab0e2deafa // indirect
+)

go.sum

@@ -0,0 +1,15 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1 h1:mweAR1A6xJ3oS2pRaGiHgQ4OO8tzTaLawm8vnODuwDk=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.4.2 h1:SPIRibHv4MatM3XXNO2BJeFLZwZ2LvZgfQ5+UNI2im4=
+github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894 h1:Cz4ceDQGXuKRnVBDTS23GTn/pU5OE2C0WrNTOYK1Uuc=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190804053845-51ab0e2deafa h1:KIDDMLT1O0Nr7TSxp8xM5tJcdn8tgyAONntO829og1M=
+golang.org/x/sys v0.0.0-20190804053845-51ab0e2deafa/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

init_test.go

@@ -0,0 +1,21 @@
+package logrusiowriter_test
+
+import (
+	"os"
+
+	"github.com/sirupsen/logrus"
+)
+
+var datelessFormatter = new(logrus.TextFormatter)
+
+func init() {
+	datelessFormatter.DisableTimestamp = true
+}
+
+// removeTimestampAndSetOutputToStdout removes date from logrus logs, and redirects them to os.Stdout
+// this can't be done in init() because os.Stdout changes after calling init() in examples:
+// see: https://unexpected-go.com/os-stdout-changes-after-init-in-examples.html
+func removeTimestampAndSetOutputToStdout(logger *logrus.Logger) {
+	logger.SetFormatter(datelessFormatter)
+	logger.SetOutput(os.Stdout)
+}