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expfmt: fix wildcard content negotiation regression for Negotiate and NegotiateIncludingOpenMetrics #966

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Merged
bwplotka merged 1 commit into from
Aug 24, 2026
Merged

expfmt: fix wildcard content negotiation regression for Negotiate and NegotiateIncludingOpenMetrics #966

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5 changes: 0 additions & 5 deletions expfmt/encode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -124,11 +124,6 @@ func matchFormat(ac goautoneg.Accept, f Format) bool {
return false
}

// If ac is */*, wildcard matches any target.
if ac.Type == "*" && ac.SubType == "*" {
return true
}

// Default OpenMetrics version to OpenMetricsVersion_0_0_1.
acVersion := ac.Params["version"]
if acVersion == "" && ac.Type+"/"+ac.SubType == OpenMetricsType {
Expand Down
40 changes: 38 additions & 2 deletions expfmt/encode_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,21 @@ func TestNegotiate(t *testing.T) {
acceptHeaderValue: "text/plain;version=0.0.4; escaping=values;",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
{
name: "wildcard */*",
acceptHeaderValue: "*/*",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=underscores",
},
{
name: "browser Accept header with wildcard",
acceptHeaderValue: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=underscores",
},
{
name: "json with wildcard fallback",
acceptHeaderValue: "application/json, */*",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=underscores",
},
}

oldDefault := model.NameEscapingScheme
Expand Down Expand Up @@ -185,6 +200,21 @@ func TestNegotiateIncludingOpenMetrics(t *testing.T) {
acceptHeaderValue: acceptValuePrefix + ";encoding=compact-text; escaping=underscores;",
expectedFmt: "application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text; escaping=underscores",
},
{
name: "wildcard */*",
acceptHeaderValue: "*/*",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
{
name: "browser Accept header with wildcard",
acceptHeaderValue: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
{
name: "json with wildcard fallback",
acceptHeaderValue: "application/json, */*",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
}

oldDefault := model.NameEscapingScheme
Expand Down Expand Up @@ -237,17 +267,23 @@ func TestNegotiateAccept(t *testing.T) {
expectedFmt: "application/openmetrics-text; version=2.0.0; charset=utf-8; escaping=values",
},
{
name: "wildcard */* matches first accepted format",
name: "wildcard */* matches text format if present",
acceptHeaderValue: "*/*",
acceptedFormats: []Format{fmtOpenMetrics_2_0_0, FmtProtoDelim, FmtText},
expectedFmt: "application/openmetrics-text; version=2.0.0; charset=utf-8; escaping=values",
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
{
name: "wildcard */* with text first in accepted",
acceptHeaderValue: "*/*",
acceptedFormats: []Format{FmtText, FmtProtoDelim},
expectedFmt: "text/plain; version=0.0.4; charset=utf-8; escaping=values",
},
{
name: "wildcard */* falls back to first format when no text in accepted",
acceptHeaderValue: "*/*",
acceptedFormats: []Format{fmtOpenMetrics_2_0_0, FmtProtoDelim},
expectedFmt: "application/openmetrics-text; version=2.0.0; charset=utf-8; escaping=values",
},
{
name: "unversioned text/plain matches FmtText",
acceptHeaderValue: "text/plain",
Expand Down
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