Division between two queries not working?

[Cole Beasley]

Hi there,

This might be a very basic question but I'm trying to get the ration of error log messages / total error messages. Using grok_exporter I have the metric type_counter which returns 

Element	Value
type_counter{instance="localhost:9144",job="grok",log_type="AUTH"}	45
type_counter{instance="localhost:9144",job="grok",log_type="ERROR"}	55
type_counter{instance="localhost:9144",job="grok",log_type="IN"}	17603
type_counter{instance="localhost:9144",job="grok",log_type="NESTED"}	971

I simply then want (type_counter{log_type="ERROR"}) / (sum(type_counter)), but this does not return a value, this is odd to me as both type_counter{log_type="ERROR"} and sum(type_counter) return their expected values and will divide by themselves or manually entered integers (such as (18,000 / sum(type_counter)). I'm not sure why the division here is not working, any ideas?

[Julius Volz]

By default, binary operators match series from the left and right side on exactly identical label sets. But you keep the log_type label on the left, while aggregating it away on the right. You can either aggregate it away on both sides:

  sum(type_counter{log_type="ERROR"}) / sum(type_counter)

...or ignore that label for matching:

  type_counter{log_type="ERROR"} / ignoring(log_type) sum(type_counter)

Btw., I assume type_counter is a counter metric. You should typically never care about the absolute value of a counter metric and instead always rate(...) it (or increase(), etc.) before using.

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Julius Volz

PromLabs - promlabs.com

[Cole Beasley]

Awesome thanks for the help! Still learning the basics.

On Tuesday, June 30, 2020 at 11:06:11 AM UTC-6, Julius Volz wrote:

By default, binary operators match series from the left and right side on exactly identical label sets. But you keep the log_type label on the left, while aggregating it away on the right. You can either aggregate it away on both sides:

  sum(type_counter{log_type="ERROR"}) / sum(type_counter)

...or ignore that label for matching:

  type_counter{log_type="ERROR"} / ignoring(log_type) sum(type_counter)

Btw., I assume type_counter is a counter metric. You should typically never care about the absolute value of a counter metric and instead always rate(...) it (or increase(), etc.) before using.

On Tue, Jun 30, 2020 at 6:11 PM Cole Beasley <colebea...@gmail.com> wrote:

Hi there,

This might be a very basic question but I'm trying to get the ration of error log messages / total error messages. Using grok_exporter I have the metric type_counter which returns 

Element	Value
type_counter{instance="localhost:9144",job="grok",log_type="AUTH"}	45
type_counter{instance="localhost:9144",job="grok",log_type="ERROR"}	55
type_counter{instance="localhost:9144",job="grok",log_type="IN"}	17603
type_counter{instance="localhost:9144",job="grok",log_type="NESTED"}	971

I simply then want (type_counter{log_type="ERROR"}) / (sum(type_counter)), but this does not return a value, this is odd to me as both type_counter{log_type="ERROR"} and sum(type_counter) return their expected values and will divide by themselves or manually entered integers (such as (18,000 / sum(type_counter)). I'm not sure why the division here is not working, any ideas?

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