Add open telemetry logging hook for logrus

This adds valuable logging data to the open telemetry traces.

When the trace is not recording we don't bother doing anything as it is
relatively expensive to convert logrus data to otel just due to the
nature of how logrus works.

The way this works is that we now set a context on the logrus.Entry that
gets passed around which the hook then uses to determine if there is an
active span to forward the logs to.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

log/context.go

@@ -52,7 +52,8 @@ const (
 // WithLogger returns a new context with the provided logger. Use in
 // combination with logger.WithField(s) for great effect.
 func WithLogger(ctx context.Context, logger *logrus.Entry) context.Context {
-	return context.WithValue(ctx, loggerKey{}, logger)
+	e := logger.WithContext(ctx)
+	return context.WithValue(ctx, loggerKey{}, e)
 }
 
 // GetLogger retrieves the current logger from the context. If no logger is
@@ -61,7 +62,7 @@ func GetLogger(ctx context.Context) *logrus.Entry {
 	logger := ctx.Value(loggerKey{})
 
 	if logger == nil {
-		return L
+		return L.WithContext(ctx)
 	}
 
 	return logger.(*logrus.Entry)

log/context_test.go

@@ -25,8 +25,6 @@ import (
 
 func TestLoggerContext(t *testing.T) {
 	ctx := context.Background()
-	assert.Equal(t, GetLogger(ctx), L)      // should be same as L variable
-	assert.Equal(t, G(ctx), GetLogger(ctx)) // these should be the same.
 
 	ctx = WithLogger(ctx, G(ctx).WithField("test", "one"))
 	assert.Equal(t, GetLogger(ctx).Data["test"], "one")