fix: escape colons in metric names when escaping=underscores#1180
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johnsaurabh wants to merge 3 commits into
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fix: escape colons in metric names when escaping=underscores#1180johnsaurabh wants to merge 3 commits into
johnsaurabh wants to merge 3 commits into
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In UNDERSCORES escaping mode, escape_metric_name was short-circuiting for names that matched the legacy Prometheus metric name regex, which allows colons. This caused # HELP and # TYPE lines to emit the raw name (e.g. sglang:token_usage) while sample lines, which use _is_legacy_labelname_rune, correctly replaced the colon with an underscore (e.g. sglang_token_usage). The mismatch violates the OpenMetrics standard and breaks strict parsers. Fix by requiring the name to also be colon-free before taking the no-op path, and switching the fallback _escape call to use _is_legacy_labelname_rune so colons are replaced consistently. Fixes prometheus#1177 Signed-off-by: John Saurabh <itsjohnsaurabh@gmail.com>
Add test_gauge_colon_in_name_escaped_underscores to verify that a gauge named sglang:token_usage produces consistent # HELP, # TYPE, and sample lines when escaping=underscores is in effect. Update two parametrized scenario expectations that documented the old buggy behaviour (colon preserved in UNDERSCORES mode): - "legacy valid metric name": no:escaping_required -> no_escaping_required - "metric name with dots and colon": http_status:sum -> http_status_sum Signed-off-by: John Saurabh <itsjohnsaurabh@gmail.com>
Mirror the same expectation corrections made to tests/openmetrics/test_exposition.py: under UNDERSCORES mode, colons in metric names are now replaced with underscores to match sample line output. Signed-off-by: John Saurabh <itsjohnsaurabh@gmail.com>
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Fixes #1177
When a metric name contains a colon (e.g.
sglang:token_usage) and the client negotiatesescaping=underscores, the# HELPand# TYPElines were emitting the raw name while the sample line replaced the colon with an underscore:This violates the OpenMetrics spec and causes strict parsers to treat the metadata and the sample as two separate metrics.
The bug is in
escape_metric_nameinprometheus_client/openmetrics/exposition.py. InUNDERSCORESmode, the function short-circuits for any name that matches the legacy Prometheus metric name regex. That regex allows colons, so names likesglang:token_usagewere returned unchanged. The sample line uses_is_legacy_labelname_runewhich does not allow colons, so it escaped them correctly.The fix adds a colon check to the short-circuit condition and switches the fallback
_escapecall to use_is_legacy_labelname_rune, matching what the sample line already does.Two existing test expectations that documented the old behavior are updated. A new end-to-end test reproduces the exact scenario from the issue.
@csmarchbanks