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new b11d00c397 stats_over_http: respect Prometheus character constraints
(#12450)
b11d00c397 is described below
commit b11d00c397ec7bb06ded05046b23f99613d0a1ea
Author: Brian Neradt <[email protected]>
AuthorDate: Wed Aug 13 12:17:36 2025 -0500
stats_over_http: respect Prometheus character constraints (#12450)
With certain configurations, metrics can have '[' and ']' characters.
Prometheus does not like these. This patch enforces that the metrics get
exported with Prometheus's advertised character set limitations:
[a-zA-Z_:][a-zA-Z0-9_:]*
Fixes: #12432
---
plugins/stats_over_http/stats_over_http.cc | 106 +++++++++++++++++++++++++++--
1 file changed, 101 insertions(+), 5 deletions(-)
diff --git a/plugins/stats_over_http/stats_over_http.cc
b/plugins/stats_over_http/stats_over_http.cc
index bd826f5d04..b2953885ca 100644
--- a/plugins/stats_over_http/stats_over_http.cc
+++ b/plugins/stats_over_http/stats_over_http.cc
@@ -473,17 +473,33 @@ csv_out_stat(TSRecordType /* rec_type ATS_UNUSED */, void
*edata, int /* registe
}
/** Replace characters offensive to Prometheus with '_'.
- * Prometheus is particular about metric names.
+ *
+ * See: https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
+ *
+ * > Metric names SHOULD match the regex [a-zA-Z_:][a-zA-Z0-9_:]*
+ * > for the best experience and compatibility
+ *
* @param[in] name The metric name to sanitize.
* @return A sanitized metric name.
*/
-static std::string
-sanitize_metric_name_for_prometheus(std::string_view name)
+static
+// Remove this check when we drop support for pre-13 GCC versions.
+#if defined(__cpp_lib_constexpr_string) && __cpp_lib_constexpr_string >=
201907L
+ constexpr
+#endif
+ std::string
+ sanitize_metric_name_for_prometheus(std::string_view name)
{
std::string sanitized_name(name);
- // Convert certain characters that Prometheus doesn't like to '_'.
+ // If the first character is a digit, prepend an underscore since Prometheus
+ // doesn't allow digits as the first character.
+ if (sanitized_name.length() > 0 && sanitized_name[0] >= '0' &&
sanitized_name[0] <= '9') {
+ sanitized_name = "_" + sanitized_name;
+ }
+ // Convert characters that Prometheus doesn't like to '_'.
+ // : letters (a-z, A-Z), digits (0-9), underscores (_), and colons (:).
for (auto &c : sanitized_name) {
- if (c == '.' || c == '+' || c == '-') {
+ if (!((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c
<= '9') || c == '_' || c == ':')) {
c = '_';
}
}
@@ -1110,3 +1126,83 @@ config_handler(TSCont cont, TSEvent /* event ATS_UNUSED
*/, void * /* edata ATS_
}
return 0;
}
+
+//
+// Compilation time unit tests.
+//
+#ifdef DEBUG
+// Remove this check when we drop support for pre-13 GCC versions.
+#if defined(__cpp_lib_constexpr_string) && __cpp_lib_constexpr_string >=
201907L
+constexpr void
+test_sanitize_metric_name_for_prometheus()
+{
+ // Various unchanged names.
+ static_assert(sanitize_metric_name_for_prometheus("foo") == "foo");
+ static_assert(sanitize_metric_name_for_prometheus("foo_bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo_bar:baz") ==
"foo_bar:baz");
+ static_assert(sanitize_metric_name_for_prometheus("FooBar123") ==
"FooBar123");
+ static_assert(sanitize_metric_name_for_prometheus("UPPERCASE_NAME") ==
"UPPERCASE_NAME");
+ static_assert(sanitize_metric_name_for_prometheus("lowercase_name") ==
"lowercase_name");
+ static_assert(sanitize_metric_name_for_prometheus("Mixed_Case_123") ==
"Mixed_Case_123");
+
+ // Test dots conversion (common in ATS metrics).
+ static_assert(sanitize_metric_name_for_prometheus("foo.bar") == "foo_bar");
+
static_assert(sanitize_metric_name_for_prometheus("proxy.process.allocator.inuse")
== "proxy_process_allocator_inuse");
+
+ // Various invalid characters.
+ static_assert(sanitize_metric_name_for_prometheus("foo-bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo+bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo@bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo#bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo$bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo%bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo^bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo&bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo*bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo(bar)") == "foo_bar_");
+ static_assert(sanitize_metric_name_for_prometheus("foo=bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo|bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo\\bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo/bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo?bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo<bar>") == "foo_bar_");
+ static_assert(sanitize_metric_name_for_prometheus("foo,bar;baz") ==
"foo_bar_baz");
+ static_assert(sanitize_metric_name_for_prometheus("foo\"bar'baz") ==
"foo_bar_baz");
+ static_assert(sanitize_metric_name_for_prometheus("foo`bar~baz") ==
"foo_bar_baz");
+ static_assert(sanitize_metric_name_for_prometheus("foo!bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo_bar[baz]") ==
"foo_bar_baz_");
+
static_assert(sanitize_metric_name_for_prometheus("proxy.process.allocator.inuse.ioBufAllocator[0]")
==
+ "proxy_process_allocator_inuse_ioBufAllocator_0_");
+
+ // Whitespace and control characters.
+ static_assert(sanitize_metric_name_for_prometheus("foo bar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo\tbar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo\nbar") == "foo_bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo\rbar") == "foo_bar");
+
+ // Initial digit variations.
+ static_assert(sanitize_metric_name_for_prometheus("0foo") == "_0foo");
+
static_assert(sanitize_metric_name_for_prometheus("1.proxy.process.allocator.inuse.ioBufAllocator[0]")
==
+ "_1_proxy_process_allocator_inuse_ioBufAllocator_0_");
+
+ // Complex combinations.
+
static_assert(sanitize_metric_name_for_prometheus("proxy.process.http.connection_errors[500].rate")
==
+ "proxy_process_http_connection_errors_500__rate");
+ static_assert(sanitize_metric_name_for_prometheus("cache.hit_ratio[0-5min]")
== "cache_hit_ratio_0_5min_");
+
static_assert(sanitize_metric_name_for_prometheus("worker.thread[0].cpu.usage%")
== "worker_thread_0__cpu_usage_");
+
static_assert(sanitize_metric_name_for_prometheus("1st.metric.name-with+special@chars")
== "_1st_metric_name_with_special_chars");
+
+ // Minimal edge cases.
+ static_assert(sanitize_metric_name_for_prometheus("") == "");
+ static_assert(sanitize_metric_name_for_prometheus("a") == "a");
+ static_assert(sanitize_metric_name_for_prometheus(".") == "_");
+ static_assert(sanitize_metric_name_for_prometheus("1") == "_1");
+
+ // Edge cases with multiple consecutive invalid characters.
+ static_assert(sanitize_metric_name_for_prometheus("foo...bar") ==
"foo___bar");
+ static_assert(sanitize_metric_name_for_prometheus("123foo---bar") ==
"_123foo___bar");
+ static_assert(sanitize_metric_name_for_prometheus("foo [[[bar]]]") ==
"foo____bar___");
+ static_assert(sanitize_metric_name_for_prometheus("foo@#$%bar") ==
"foo____bar");
+}
+#endif // defined(__cpp_lib_constexpr_string) && __cpp_lib_constexpr_string >=
201907L
+#endif // DEBUG
