Inconsistent encoding of units in metric names

[streadway]

The lack of units for the counter scalars has lead to encoding them in the docstring, or metric name itself. Does it make sense to use a label for units? It seems we have a metric level special meaning for the "name" label, does this extend also to "units"?

Examples of confusing names with the units encoded in different locations in the names, and in the docstring.

namespace_metric_units vs. namespace_units_metric

• "http_request_durations_microseconds", "The amounts of time the default multiplexor has spent answering HTTP requests (microseconds)."
• "http_request_bytes_total", "The total volume of content body sizes received (bytes)."

[juliusv]

Since labels do come at a cost, IMO they should not be used for "documentation" purposes, i.e. for cases where they don't actually introduce new dimensionality. Unless you are exporting the same metric with different units (uncommon), a unit label wouldn't add any new dimension, so I'd rather advise against this and keep using a naming convention.

[streadway]

I would suggest documenting a grammar for the naming convention then so we don't mix up "bytes_total" with "total_bytes", or "ms_elapsed" with "elapsed_milliseconds".

{namespace (lowercase, shared with any --flags)}_{metric name lowercase, underscore delimited}_{units in full, lower case SI notation with no underscores}

[matttproud]

A WIP on conventions: https://github.com/prometheus/prometheus/wiki/Metric-and-Label-Conventions.

[brian-brazil]

Labels for units don't make sense, having them as metadata (similar to whether something is a counter or gauge) would be useful though.

If we can get everyone on un-prefixed SI units as much as possible that'd be good. We already seem to have a mix of microseconds, milliseconds, and seconds.

[juliusv]

@brian-brazil If you use unprefixed SI units (seconds in case of time) and you want to measure something in the nanosecond range, the result becomes much less readable though?

[brian-brazil]

I think that everything should be exported, stored and calculated in seconds - and only when rendering for human display to change to nanoseconds. This is similar logic to why you should always use unixtime when processing, and only apply timezones when rendering.

[juliusv]

This got resolved a while ago, closing.

[lock]

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