chore(metrics): allow dot in the scope value (#1019)

crates/metrics/metrics-derive/src/expand.rs

@@ -11,7 +11,7 @@ use crate::{metric::Metric, with_attrs::WithAttrs};
 /// Metric name regex according to Prometheus data model
 /// https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
 static METRIC_NAME_RE: Lazy<Regex> =
-    Lazy::new(|| Regex::new(r"^[a-zA-Z_:][a-zA-Z0-9_:]*$").unwrap());
+    Lazy::new(|| Regex::new(r"^[a-zA-Z_:.][a-zA-Z0-9_:.]*$").unwrap());
 
 /// Supported metrics separators
 const SUPPORTED_SEPARATORS: &[&str] = &[".", "_", ":"];

crates/metrics/metrics-derive/tests/compile-fail/metrics_attr.rs

@@ -24,7 +24,7 @@ struct CustomMetrics4;
 struct CustomMetrics5;
 
 #[derive(Metrics)]
-#[metrics(scope = "some.scope")]
+#[metrics(scope = "some-scope")]
 struct CustomMetrics6;
 
 #[derive(Metrics)]

crates/metrics/metrics-derive/tests/compile-fail/metrics_attr.stderr

@@ -29,10 +29,10 @@ error: Value **must** be a string literal.
 23 | #[metrics(scope = 123)]
    |                   ^^^
 
-error: Value must match regex ^[a-zA-Z_:][a-zA-Z0-9_:]*$
+error: Value must match regex ^[a-zA-Z_:.][a-zA-Z0-9_:.]*$
   --> tests/compile-fail/metrics_attr.rs:27:19
    |
-27 | #[metrics(scope = "some.scope")]
+27 | #[metrics(scope = "some-scope")]
    |                   ^^^^^^^^^^^^
 
 error: Duplicate `scope` value provided.