Add an option to send histograms/summary counts as monotonic counters

[mfpierre]

What does this PR do?

Add an option to send histograms & summaries counts as monotonic_counter

Motivation

Using monotonic counts for counters is more appropriate is most cases

Additional Notes

Anything else we should know when reviewing?

Review checklist (to be filled by reviewers)

• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached
• Feature or bugfix must have tests
• Git history must be clean
• If PR adds a configuration option, it must be added to the configuration file.

[codecov]

Codecov Report

Merging #4629 into master will decrease coverage by 0.37%.
The diff coverage is 100%.

Impacted Files	Coverage Δ
...e/datadog_checks/base/checks/openmetrics/mixins.py	77.53% <100%> (+0.27%)	⬆️
datadog_checks_base/tests/test_openmetrics.py	98.96% <100%> (+0.05%)	⬆️
vertica/tests/metrics.py
lighttpd/tests/test_check.py
vertica/datadog_checks/vertica/views.py
win32_event_log/tests/test_check.py
cassandra_nodetool/tests/test_e2e.py
vertica/tests/conftest.py
php_fpm/datadog_checks/php_fpm/__about__.py
gitlab/tests/conftest.py
... and 107 more

[AlexandreYang]

Using monotonic counts for counters is more appropriate is most cases

Is using a flag like send_counts_as_monotonic an issue if we want only some of the metrics to be send as monotonic counts ?

As you said above, it might be appropriate for most cases, but maybe not all cases.

Would it be more appropriate to provide a way to supply a specific type for each metric ? Example:

    def __init__(self, name, init_config, agentConfig, instances=None):
        super(CrioCheck, self).__init__(
            ...
            default_instances={
                "crio": {
                    ...
                    'metrics': [
                        {'container_runtime_crio_operations1': ('operations.count', GAUGE)},
                        {'container_runtime_crio_operations2': ('operations.count', COUNT)},
                        {'container_runtime_crio_operations_latency_microseconds': ('operations.latency', MONOTONIC_COUNT)},
                    ],
                    ...
                }
            },
        )

[mfpierre]

@AlexandreYang actually there's already a setting for this called send_monotonic_counter that would send counter typed metrics as monotonic_counter (ever increasing value). Note that's what you're suggesting is already possible via type override.

This change is only for the counters inside summary/histograms metrics.

[AlexandreYang]

Oh, right. Thx for the explanation.

So there is no case, where you might want to send some distribution counts as count and some other as monotonic count ?

[AlexandreYang]

Since that's quite specific to distribution metrics. Should the name be a bit more precise like: send_distribution_counts_as_monotonic ?

Otherwise, this might be confused with sending all counts as monotonic.

[AlexandreYang]

LGTM. Maybe be nice to have a review from @DataDog/container-integrations too.