gkelog: Add some convenience functions for logging with severity

emitter/gkelog/emitter.go

@@ -30,19 +30,6 @@ var (
 	spanKey     = contextKey("span")
 )
 
-// Severity levels
-const (
-	SeverityDefault   = "DEFAULT"   // The log entry has no assigned severity level.
-	SeverityDebug     = "DEBUG"     // Debug or trace information.
-	SeverityInfo      = "INFO"      // Routine information, such as ongoing status or performance.
-	SeverityNotice    = "NOTICE"    // Normal but significant events, such as start up, shut down, or a configuration change.
-	SeverityWarning   = "WARNING"   // Warning events might cause problems.
-	SeverityError     = "ERROR"     // Error events are likely to cause problems.
-	SeverityCritical  = "CRITICAL"  // Critical events cause more severe problems or outages.
-	SeverityAlert     = "ALERT"     // A person must take an action immediately.
-	SeverityEmergency = "EMERGENCY" // One or more systems are unusable.
-)
-
 // WithSeverity returns a copy of parent with the specified severity value.
 func WithSeverity(parent context.Context, severity string) context.Context {
 	return context.WithValue(parent, severityKey, severity)

emitter/gkelog/emitter_test.go

@@ -75,6 +75,20 @@ func TestSeverity(t *testing.T) {
 	}
 }
 
+func TestLogSeverity(t *testing.T) {
+	b := &bytes.Buffer{}
+	ctx := context.Background()
+	l := alog.New(alog.WithEmitter(Emitter(WithWriter(b))), zeroTimeOpt)
+
+	LogInfo(ctx, l, "test")
+
+	want := `{"time":"0001-01-01T00:00:00Z", "severity":"INFO", "message":"test"}` + "\n"
+	got := b.String()
+	if got != want {
+		t.Errorf("got:\n%s\nwant:\n%s", got, want)
+	}
+}
+
 func TestRequest(t *testing.T) {
 	b := &bytes.Buffer{}
 	ctx := context.Background()

emitter/gkelog/severity.go

@@ -0,0 +1,60 @@
+package gkelog
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/vimeo/alog/v3"
+)
+
+// Severity levels
+const (
+	SeverityDefault   = "DEFAULT"   // The log entry has no assigned severity level.
+	SeverityDebug     = "DEBUG"     // Debug or trace information.
+	SeverityInfo      = "INFO"      // Routine information, such as ongoing status or performance.
+	SeverityNotice    = "NOTICE"    // Normal but significant events, such as start up, shut down, or a configuration change.
+	SeverityWarning   = "WARNING"   // Warning events might cause problems.
+	SeverityError     = "ERROR"     // Error events are likely to cause problems.
+	SeverityCritical  = "CRITICAL"  // Critical events cause more severe problems or outages.
+	SeverityAlert     = "ALERT"     // A person must take an action immediately.
+	SeverityEmergency = "EMERGENCY" // One or more systems are unusable.
+)
+
+// Separate private function so that LogSeverity and the other logs functions
+// will have the same stack frame depth and thus use the same calldepth value.
+// See https://golang.org/pkg/runtime/#Caller and
+// https://godoc.org/github.com/vimeo/alog#Logger.Output
+func logSeverity(ctx context.Context, logger *alog.Logger, s string, f string, v ...interface{}) {
+	ctx = WithSeverity(ctx, s)
+	logger.Output(ctx, 3, fmt.Sprintf(f, v...))
+}
+
+// LogSeverity writes a log entry using the specified severity
+func LogSeverity(ctx context.Context, logger *alog.Logger, severity string, f string, v ...interface{}) {
+	logSeverity(ctx, logger, severity, f, v...)
+}
+
+// LogDebug writes a log entry using SeverityDebug
+func LogDebug(ctx context.Context, logger *alog.Logger, f string, v ...interface{}) {
+	logSeverity(ctx, logger, SeverityDebug, f, v...)
+}
+
+// LogInfo writes a log entry using SeverityInfo
+func LogInfo(ctx context.Context, logger *alog.Logger, f string, v ...interface{}) {
+	logSeverity(ctx, logger, SeverityInfo, f, v...)
+}
+
+// LogWarning writes a log entry using SeverityWarning
+func LogWarning(ctx context.Context, logger *alog.Logger, f string, v ...interface{}) {
+	logSeverity(ctx, logger, SeverityWarning, f, v...)
+}
+
+// LogError writes a log entry using SeverityError
+func LogError(ctx context.Context, logger *alog.Logger, f string, v ...interface{}) {
+	logSeverity(ctx, logger, SeverityError, f, v...)
+}
+
+// LogCritical writes a log entry using SeverityCritical
+func LogCritical(ctx context.Context, logger *alog.Logger, f string, v ...interface{}) {
+	logSeverity(ctx, logger, SeverityCritical, f, v...)
+}