Add Cassandra driver Actuator metrics by emerkle826 · Pull Request #21624 · spring-projects/spring-boot

emerkle826 · 2020-05-29T19:28:55Z

Motivation:

The DataStax Java driver for Cassandra can be configured to expose driver session operational metrics. Currently these metrics are not available through Spring Boot Actuator.

Modifications:

This commit adds support for Cassandra driver metrics through Spring Boot Actuator by binding the native driver metrics to Micrometer metrics.

Result:

Users are now able to access Cassandra driver enabled metrics through Actuator .

mrcnc · 2020-05-29T20:04:53Z

Any reason why the copyright ends at 2019 instead of 2020?

oversight, from a copy-paste

adutra · 2020-05-31T10:21:42Z

Small typo here: Guage -> Gauge.

thanks for catching that!

shakuzen

Converting from Dropwizard metrics to Micrometer metrics tends to be lossy and have an impedance mismatch. Furthermore, if a MeterBinder is the solution that ends up being used, I'm not sure it belongs in Spring Boot as there is nothing specific to Spring or Spring Boot in it - either the Cassandra driver or Micrometer would seem more appropriate. Spring Boot could make use of that, then. That said, rather than mapping to non-idiomatic Micrometer metrics, it would be best if the Cassandra driver either:

supported Micrometer directly as an option. Or
had hooks so that Micrometer could instrument the metrics natively, without passing through Dropwizard metrics.

See micrometer-metrics/micrometer#1397 and micrometer-metrics/micrometer#1359

shakuzen · 2020-06-15T12:51:32Z

+	/**
+	 * Description for micrometer metrics.
+	 */
+	private static final String DESCRIPTION = "Please see reference.conf for more information.";


I'm not sure what reference.conf is but this does not seem like a useful description, in my opinion. Descriptions may be published to metric backends, which almost certainly won't have access to the mentioned reference.conf. Even accessing the Actuator endpoint does not mean that person has access to this reference.conf file.

shakuzen · 2020-06-15T12:57:49Z

+
+		TIMER_METRICS.forEach((n, supplier) -> {
+			String nameTimerMetric = String.format("%s.%s", name, n);
+			FunctionCounter.builder(nameTimerMetric, timer, (t) -> supplier.apply(timer).doubleValue()).tags(this.tags)


Counters, including FunctionCounter, in Micrometer are expected to be monotonically increasing, which is not the case with these rates, I believe. If you were to convert these, they would be gauges in Micrometer.

shakuzen · 2020-06-15T12:58:50Z

+			String nameTimerMetric = String.format("%s.%s", name, n);
+			FunctionCounter.builder(nameTimerMetric, timer, (t) -> supplier.apply(timer).doubleValue()).tags(this.tags)
+					// all rates are calculated per second
+					.baseUnit(TimeUnit.SECONDS.name()).description(DESCRIPTION).register(meterRegistry);


The rate is per second; not counting seconds, which is what this ends up seeming like - a count of seconds.

shakuzen · 2020-06-15T13:00:41Z

+		final Snapshot snapshot = timer.getSnapshot();
+		TIMER_SNAPSHOT_METRICS.forEach((n, supplier) -> {
+			String nameTimerMetric = String.format("%s.%s", name, n);
+			FunctionCounter.builder(nameTimerMetric, timer, (t) -> supplier.apply(snapshot).longValue()).tags(this.tags)


Again, not monotonically increasing (except for max) so should not be a FunctionCounter.

shakuzen · 2020-06-15T13:25:04Z

+	/**
+	 * Prefix for all Driver configuration parameters.
+	 */
+	public static final String SESSION_PREFIX = "spring.data.cassandra.driver.session";


Are there metrics not related to sessions available?

emerkle826 · 2020-06-15T20:12:11Z

Converting from Dropwizard metrics to Micrometer metrics tends to be lossy and have an impedance mismatch. Furthermore, if a MeterBinder is the solution that ends up being used, I'm not sure it belongs in Spring Boot as there is nothing specific to Spring or Spring Boot in it - either the Cassandra driver or Micrometer would seem more appropriate. Spring Boot could make use of that, then. That said, rather than mapping to non-idiomatic Micrometer metrics, it would be best if the Cassandra driver either:
* supported Micrometer directly as an option. Or

* had hooks so that Micrometer could instrument the metrics natively, without passing through Dropwizard metrics.
See micrometer-metrics/micrometer#1397 and micrometer-metrics/micrometer#1359

Thank you for the review, you have valid points about this sort of metrics binding not being specific to Spring. We (the driver team at Datastax) have discussed it further and have decided to try the approach of providing different metrics bindings for the Cassandra driver (ticket is here).

I'll convert this to a draft PR and revisit it once that work is completed.

snicoll · 2020-06-16T05:47:23Z

@emerkle826 thanks for the follow up!

snicoll · 2020-07-08T14:12:04Z

@emerkle826 does this PR still make sense? I understand some major changes are pending in the driver so I am wondering if you would reuse this PR to update us. Thank you.

emerkle826 · 2020-07-08T14:16:43Z

@snicoll I think this PR will become obsolete once we make changes on the driver side. I'll close it. If a change still needs to happen in Spring Boot after the driver changes, I'll open a new PR as it will most likely not resemble this one much at all.

snicoll · 2020-07-08T14:20:52Z

Thanks for confirming. Let us know if we can help!

spring-projects-issues added the status: waiting-for-triage An issue we've not yet triaged label May 29, 2020

mrcnc reviewed May 29, 2020

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philwebb added the for: team-attention An issue we'd like other members of the team to review label May 29, 2020

adutra reviewed May 31, 2020

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adutra mentioned this pull request May 31, 2020

Add Cassandra driver Actuator metrics datastax-archive/spring-boot#2

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Add Cassandra driver Actuator metrics

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philwebb added type: enhancement A general enhancement and removed for: team-attention An issue we'd like other members of the team to review status: waiting-for-triage An issue we've not yet triaged labels Jun 11, 2020

philwebb added this to the 2.4.x milestone Jun 11, 2020

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emerkle826 marked this pull request as draft June 15, 2020 20:12

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emerkle826 closed this Jul 8, 2020

snicoll removed status: blocked An issue that's blocked on an external project change type: enhancement A general enhancement labels Jul 8, 2020

snicoll removed this from the 2.4.x milestone Jul 8, 2020

snicoll added the status: superseded An issue that has been superseded by another label Jul 8, 2020

emerkle826 mentioned this pull request Aug 19, 2020

Add Cassandra driver Actuator metrics #23008

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emerkle826 commented Jun 15, 2020

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