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HPCC-31227 Address Prometheous histogram issues #18293

Merged
merged 1 commit into from
Feb 15, 2024
Merged

HPCC-31227 Address Prometheous histogram issues #18293

merged 1 commit into from
Feb 15, 2024

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rpastrana
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@rpastrana rpastrana commented Feb 9, 2024 •
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  • Fixes invalid quote on le=+Inf bucket
  • Qualifies sum and count w/ metric name
  • Normalizes all names to lowercase per promtool suggestion

Type of change:

  • This change is a bug fix (non-breaking change which fixes an issue).
  • This change is a new feature (non-breaking change which adds functionality).
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HPCC-31227 Address Prometheous histogram issues
fcc03b0 
 - Fixes invalid quote on le=+Inf bucket
 - Qualifies sum and count w/ metric name
 - Normalizes all names to lowercase per promtool suggestion

Signed-off-by: Rodrigo Pastrana <[email protected]>
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github-actions bot commented Feb 9, 2024

https://track.hpccsystems.com/browse/HPCC-31227
Jira updated

@rpastrana
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@ghalliday targeting latest point branch, but it seems this feature has been broken since its inception (#16624) which seems to have been included as far back as 8.12.x

@rpastrana rpastrana requested a review from kenrowland February 9, 2024 20:00
rpastrana
rpastrana commented Feb 9, 2024
View reviewed changes
system/metrics/sinks/prometheus/prometheusSink.cpp
@@ -180,6 +180,9 @@ void PrometheusMetricSink::toPrometheusHistogram(const std::string &name, const
std::string PrometheusMetricSink::getPrometheusMetricName(const std::shared_ptr<IMetric> &pMetric)
{
std::string name = pMetric->queryName();
// Convert to lower case - per promtool output: "metric names should be written in 'snake_case' not 'camelCase'"
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Perhaps out of scope of this issue, but lower casing all metric names per Prometheus promtool output:
dfs_8880_WsDfs_KeepAlive_seconds metric names should be written in 'snake_case' not 'camelCase'
dfs_8880_WsDfs_KeepAlive_seconds no help text

rpastrana
rpastrana commented Feb 9, 2024
View reviewed changes
system/metrics/sinks/prometheus/prometheusSink.cpp
@@ -240,16 +243,16 @@ const std::vector<std::string> &PrometheusMetricSink::getHistogramLabels(const s

// Add the inf label
std::string infLabel(name);
infLabel.append("_bucket{\"le=+Inf\"}");
infLabel.append("_bucket{le=\"+Inf\"}");
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Incorrect double quote location

rpastrana
rpastrana commented Feb 9, 2024
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system/metrics/sinks/prometheus/prometheusSink.cpp
labels.emplace_back(infLabel);

// Sum and count
std::string sumLabel;
sumLabel.append("_sum");
std::string sumLabel(name);
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_sum and _count missing metric name prefix

@rpastrana
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No more "INVALID" errors in prometheous ui:
image

Sample histogram metric accepted by prom chart ui:
image

kenrowland
kenrowland requested changes Feb 9, 2024
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system/metrics/sinks/prometheus/prometheusSink.cpp
std::string countLabel;
countLabel.append("_count");
std::string countLabel(name);
countLabel.append("_count{}");
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@kenrowland kenrowland Feb 9, 2024 •
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Curious why the '{}" is present. Braces are not part of what is shown on the Prometheus page documenting their exposition formats. See https://prometheus.io/docs/instrumenting/exposition_formats/

Please double check the reason for "{}" in both places where added

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Great observation, it's legal syntax as confirmed by promtool and prometheous graph UI used as a label container. It's optional, and honestly it was added as I tested why your histograms were deemed invalid.

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What stands out to me is the fact there's currently no mechanism (at least not one I could see) to populate the histogram buckets w/ any available metadata as labels. That will likely need to be fixed.

@rpastrana rpastrana requested a review from kenrowland February 9, 2024 21:39
kenrowland
kenrowland approved these changes Feb 9, 2024
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Based on comment that promtool accepted the {} appended to the histogram sum and count outputs.

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@ghalliday please merge. Currently targeting 9.4.x, but not sure if we should back port. This fixes a feature introduced in 8.12.x but to the best of my knowledge it never worked quite right for Prometheus

@ghalliday ghalliday merged commit 3a6806f into hpcc-systems:candidate-9.4.x Feb 15, 2024
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@rpastrana @kenrowland @ghalliday