More tweaks for SSM instrumentation

I'm not duplicating this annotation key anymore, although the setting of
the variable and read in defer might be weirder...

I'm also recording an error if the context is canceled, but if X-Ray
can't do OTel events then maybe this is broken too?

Author: featherbread

internal/slack/token.go

@@ -77,6 +77,8 @@ func AWSParameter(name string, ttl time.Duration) TokenProvider {
 	)
 
 	return func(ctx context.Context) (string, error) {
+		var cached bool
+
 		ctx, span := tracer.Start(ctx, "slack.AWSParameter")
 		defer span.End()
 
@@ -85,18 +87,20 @@ func AWSParameter(name string, ttl time.Duration) TokenProvider {
 			defer func() {
 				<-lock
 				span.SetAttributes(
+					attribute.Bool("randomizer.slack.ssm.cached", cached),
 					attribute.Int64("randomizer.slack.ssm.expiry", expiry.Unix()))
 			}()
+
 		case <-ctx.Done():
+			span.RecordError(ctx.Err())
 			return "", ctx.Err()
 		}
 
 		if time.Now().Before(expiry) {
-			span.SetAttributes(attribute.Bool("randomizer.slack.ssm.cached", true))
+			cached = true
 			return token, nil
 		}
 
-		span.SetAttributes(attribute.Bool("randomizer.slack.ssm.cached", false))
 		cfg, err := awsconfig.New(ctx)
 		if err != nil {
 			return "", err