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Fix Prometheus exporter to sanitize malformed unit strings #7063

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Fix Prometheus exporter to sanitize malformed unit strings #7063

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36 changes: 36 additions & 0 deletions src/OpenTelemetry.Exporter.Prometheus.HttpListener/Internal/PrometheusMetric.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -119,6 +119,41 @@ static StringBuilder CreateStringBuilder(string name)
}
}

internal static string SanitizeUnitName(string unit)
{
if (string.IsNullOrEmpty(unit))
{
return string.Empty;
}

var sb = new StringBuilder(unit.Length);
var lastCharUnderscore = false;

for (var i = 0; i < unit.Length; i++)
{
var c = unit[i];

if (char.IsLetterOrDigit(c))
{
sb.Append(c);
lastCharUnderscore = false;
}
else if (!lastCharUnderscore && sb.Length > 0)
{
sb.Append('_');
lastCharUnderscore = true;
}
}

// Strip trailing underscore
if (sb.Length > 0 && sb[sb.Length - 1] == '_')
{
sb.Length--;
}

return sb.Length == 0 ? string.Empty : sb.ToString();
}

internal static string RemoveAnnotations(string unit)
{
// UCUM standard says the curly braces shouldn't be nested:
Expand Down Expand Up @@ -208,6 +243,7 @@ private static string GetUnit(string unit)
updatedUnit = MapUnit(updatedUnit.AsSpan());
}

updatedUnit = SanitizeUnitName(updatedUnit);
return updatedUnit;
}

Expand Down
38 changes: 37 additions & 1 deletion test/OpenTelemetry.Exporter.Prometheus.HttpListener.Tests/PrometheusMetricTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -263,6 +263,42 @@ public void GetPrometheusType_MapsOpenTelemetryMetricsTypeToPrometheus(MetricsMa
[Fact]
public void Name_EmptyUnit_NoSuffixAdded() => AssertName("metric", string.Empty, PrometheusType.Gauge, false, "metric");

[Fact]
public void Name_MalformedUnit_HashRU_Sanitized()
=> AssertName("metric", "# RU", PrometheusType.Gauge, false, "metric_RU");

[Fact]
public void Name_MalformedUnit_HashOnly_Unitless()
=> AssertName("metric", "#", PrometheusType.Gauge, false, "metric");

[Fact]
public void Name_MalformedUnit_HashSpaceHash_Unitless()
=> AssertName("metric", "# #", PrometheusType.Gauge, false, "metric");

[Fact]
public void Name_MalformedUnit_HashUnderscoreRDotUDot_Sanitized()
=> AssertName("metric", "#_R.U.", PrometheusType.Gauge, false, "metric_R_U");

[Fact]
public void SanitizeUnitName_Valid()
=> Assert.Equal("bytes", PrometheusMetric.SanitizeUnitName("bytes"));

[Fact]
public void SanitizeUnitName_WithInvalidChars()
=> Assert.Equal("RU", PrometheusMetric.SanitizeUnitName("# RU"));

[Fact]
public void SanitizeUnitName_OnlyInvalidChars_ReturnsEmpty()
=> Assert.Equal(string.Empty, PrometheusMetric.SanitizeUnitName("#"));

[Fact]
public void SanitizeUnitName_Empty_ReturnsEmpty()
=> Assert.Equal(string.Empty, PrometheusMetric.SanitizeUnitName(string.Empty));

[Fact]
public void SanitizeUnitName_DotsCollapsed()
=> Assert.Equal("R_U", PrometheusMetric.SanitizeUnitName("R.U."));

[Fact]
public void Name_NullUnit_NoSuffixAdded()
{
Expand Down Expand Up @@ -361,7 +397,7 @@ public void GetPrometheusType_HistogramVariants_ReturnsHistogram(int metricTypeV

[Fact]
public void Name_MultipleSlashesInUnit_FirstSlashProcessed()
=> AssertName("metric", "req/s/extra", PrometheusType.Gauge, false, "metric_req_per_s/extra"); // // Multiple slashes
=> AssertName("metric", "req/s/extra", PrometheusType.Gauge, false, "metric_req_per_s_extra"); // Multiple slashes

[Theory]
[InlineData(PrometheusType.Counter)]
Expand Down