Use development logging when running a local build (#889)

* Use development logging when running a local build

The [zap development
logger](https://godoc.org/go.uber.org/zap#NewDevelopmentConfig) provides nicer
console output as well as a few other different defaults for development.

To decide whether to use production or development it's checking if `Version`
has been set at build time. If not it assumes it's development. It may be
better not to conflate version number with build type in which case we could
add a separate build type. But first I wanted to see if the general idea
desirable.

* add log profile flag

* add build variable

Makefile

@@ -29,14 +29,17 @@ LINT=golangci-lint
 IMPI=impi
 GOSEC=gosec
 STATIC_CHECK=staticcheck
+# BUILD_TYPE should be one of (dev, release).
+BUILD_TYPE?=release
 
 GIT_SHA=$(shell git rev-parse --short HEAD)
 BUILD_INFO_IMPORT_PATH=github.com/open-telemetry/opentelemetry-collector/internal/version
 BUILD_X1=-X $(BUILD_INFO_IMPORT_PATH).GitHash=$(GIT_SHA)
 ifdef VERSION
 BUILD_X2=-X $(BUILD_INFO_IMPORT_PATH).Version=$(VERSION)
 endif
-BUILD_INFO=-ldflags "${BUILD_X1} ${BUILD_X2}"
+BUILD_X3=-X $(BUILD_INFO_IMPORT_PATH).BuildType=$(BUILD_TYPE)
+BUILD_INFO=-ldflags "${BUILD_X1} ${BUILD_X2} ${BUILD_X3}"
 
 all-srcs:
 	@echo $(ALL_SRC) | tr ' ' '\n' | sort

internal/version/version.go

@@ -20,12 +20,30 @@ import (
 	"runtime"
 )
 
+const (
+	buildDev     = "dev"
+	buildRelease = "release"
+)
+
 // Version variable will be replaced at link time after `make` has been run.
 var Version = "latest"
 
 // GitHash variable will be replaced at link time after `make` has been run.
 var GitHash = "<NOT PROPERLY GENERATED>"
 
+// BuildType should be one of (dev, release).
+var BuildType = buildDev
+
+// IsDevBuild returns true if this is a development (local) build.
+func IsDevBuild() bool {
+	return BuildType == buildDev
+}
+
+// IsReleaseBuild returns true if this is a release build.
+func IsReleaseBuild() bool {
+	return BuildType == buildRelease
+}
+
 // Info returns a formatted string, with linebreaks, intended to be displayed
 // on stdout.
 func Info() string {

service/logger.go

@@ -19,19 +19,24 @@ import (
 
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
+
+	"github.com/open-telemetry/opentelemetry-collector/internal/version"
 )
 
 const (
-	logLevelCfg = "log-level"
+	logLevelCfg   = "log-level"
+	logProfileCfg = "log-profile"
 )
 
 var (
 	// Command line pointer to logger level flag configuration.
-	loggerLevelPtr *string
+	loggerLevelPtr   *string
+	loggerProfilePtr *string
 )
 
 func loggerFlags(flags *flag.FlagSet) {
 	loggerLevelPtr = flags.String(logLevelCfg, "INFO", "Output level of logs (DEBUG, INFO, WARN, ERROR, DPANIC, PANIC, FATAL)")
+	loggerProfilePtr = flags.String(logProfileCfg, "", "Logging profile to use (dev, prod)")
 }
 
 func newLogger() (*zap.Logger, error) {
@@ -40,7 +45,22 @@ func newLogger() (*zap.Logger, error) {
 	if err != nil {
 		return nil, err
 	}
+
 	conf := zap.NewProductionConfig()
+
+	// Use logger profile if set on command line before falling back
+	// to default based on build type.
+	switch *loggerProfilePtr {
+	case "dev":
+		conf = zap.NewDevelopmentConfig()
+	case "prod":
+		conf = zap.NewProductionConfig()
+	default:
+		if version.IsDevBuild() {
+			conf = zap.NewDevelopmentConfig()
+		}
+	}
+
 	conf.Level.SetLevel(level)
 	return conf.Build()
 }