Make Labels Optional for CounterMetric::add #1032

astorm · 2020-05-07T00:24:41Z

Which problem is this PR solving?

This solves the problem described in #1031 -- where not providing labels to a counter metric results in an error.

Short description of the changes

This PR changes the method signature of the add method on the CounterMetric class to provide a default value for the labels parameter. This is done so that the hashLabels utility function does not throw an error when trying to pass undefined to Object.keys(labels);

This PR also adds a new unit test to exercise the default option.

mayurkale22 · 2020-05-07T00:34:09Z

packages/opentelemetry-metrics/src/Metric.ts

@@ -133,7 +133,7 @@ export class CounterMetric extends Metric<BoundCounter> implements api.Counter {
   * @param labels key-values pairs that are associated with a specific metric
   *     that you want to record.
   */
-  add(value: number, labels: api.Labels) {
+  add(value: number, labels: api.Labels = {}) {


This is nice, it would be nice if you can do the same thing to measure.record (https://github.com/astorm/opentelemetry-js/blob/astorm/labels-optional/packages/opentelemetry-metrics/src/Metric.ts#L166)

Just realized, Prometheus exporter would fail after this change. Especially below line due to toString method on undefined:

opentelemetry-js/packages/opentelemetry-exporter-prometheus/src/prometheus.ts

Line 187 in c454d6c

...record.descriptor.labelKeys.map(k => record.labels[k].toString())

I would prefer to fix it in this same PR and do some end to end manual testing. WDYT?

Also, in order to pass the build you need to make the same change in the API package.

Thanks for the guidance and patience @mayurkale22 -- I'm new to the repo and the project and I'm still getting my sea legs.

Fixing this for the MeasureMetric in this PR makes sense. Fixing the prometheus exporter in this PR also makes sense. I presume the change in opentelemetry-api would be to the interfaces, and that also makes sense to do in this PR.

I'll ping -- you? -- via a PR comment when that's done. If there's more to The Process™ please let me know.

Best wishes.

SGTM, just add a comment on this thread when new changes are ready to review. I usually use this example to test against prom. exporter.

@mayurkale22 not sure why you think the prometheus exporter would fail on that line. Can you explain? I'm hesitant to approve changes to the _registerMetric routine in the prometheus exporter because the prom-client has some surprising behavior, and that is the logic we use to destroy and recreate the counters with the new values.

@mayurkale22 not sure why you think the prometheus exporter would fail on that line. Can you explain?

Looks like @astorm already mention the reason, here-> #1032 (comment) (due to toString method on undefined label value).

I'm hesitant to approve changes to the _registerMetric routine in the prometheus exporter because the prom-client ....

I would suggest to add new test in prom. exporter with some LabelKeys but w/o Labels (values). You can reuse existing test (like this one), just dont bind the labels to metric.

astorm · 2020-05-07T04:56:00Z

@mayurkale22 (or others) -- I've

updated the MeasureMetric.record signature so labels is optional with a default value of {} -- existing test coverage seems sufficient here, so I did not add an additional unit test.
updated interface Counter and interface Measure to make labels an optional parameter there as well

Regarding Prometheus -- I left a question in the gitter room about this, but I can't get the prometheus exporter package to build cleanly. When running npm install from the root, I end up with the following results. TLDR -- is seems like the prometheus package at master can't compile right now.

test/prometheus.test.ts:527:5 - error TS7027: Unreachable code detected.

527     done();
        ~~~~~~~


Found 2 errors.

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @opentelemetry/[email protected] compile: `npm run version:update && tsc -p .`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the @opentelemetry/[email protected] compile script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/alanstorm/.npm/_logs/2020-05-07T03_59_24_975Z-debug.log
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: @opentelemetry/[email protected]
lerna info lifecycle @opentelemetry/[email protected]~prepare: Failed to exec prepare script.

Before I go off on some yak shave, does anyone reading have any advice on how I might proceed to a clean build. One I have a clean build I can make a pass at fixing the prometheus exporter so it doesn't assume counter metrics have labels.

codecov-io · 2020-05-07T06:42:48Z

Codecov Report

Merging #1032 into master will decrease coverage by 16.47%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #1032       +/-   ##
===========================================
- Coverage   95.09%   78.61%   -16.48%     
===========================================
  Files         212       72      -140     
  Lines        8903     1791     -7112     
  Branches      801      252      -549     
===========================================
- Hits         8466     1408     -7058     
+ Misses        437      383       -54

Impacted Files	Coverage Δ
packages/opentelemetry-api/src/metrics/Metric.ts	`100.00% <ø> (ø)`
packages/opentelemetry-core/test/utils/url.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...ckages/opentelemetry-core/test/platform/id.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...s/opentelemetry-core/src/platform/node/sdk-info.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...pentelemetry-core/src/platform/node/performance.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...pentelemetry-core/test/internal/validators.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...ntelemetry-core/test/trace/NoRecordingSpan.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...telemetry-core/test/platform/hex-to-base64.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...elemetry-core/test/trace/spancontext-utils.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
...lemetry-core/test/trace/ProbabilitySampler.test.ts	`0.00% <0.00%> (-100.00%)`	⬇️
... and 142 more

mayurkale22 · 2020-05-07T07:01:07Z

test/prometheus.test.ts:527:5 - error TS7027: Unreachable code detected.

I tried repro'd it locally, seems working fine for me.

astorm · 2020-05-07T07:33:31Z

@mayurkale22 OK -- I was able to work around (but not fix) my repo/learna issues and fix the Prometheus exporter for the case where A metric's been defined with set of label keys, but values are not provided when recording the metric (either by passing a {} to add, or by using this new default value and passing nothing to add)

My main interest in this PR is being able to create a simple counter with no labels and increment it. As this PR sits right now, I think we've accomplished that, but if there's more to be done here please let me know.

Also -- just to say it out loud -- there seems to be a non-symmetry to the API design that exists regardless of this PR. The fact you can define a set of label keys for a metric, but then not define values for those keys when recording a metric creates some ambiguity as far as what the correct behavior should be (Record with undefined values for that key(s)? Throw an error because the keys are there? Log an error but still record? Log an error but don't record?) I'm not sure if anything can/should be done about this, but if there is it feels outside the scope of this small PR.

Thanks again for considering this and for the help getting oriented in the repo.

dyladan · 2020-05-07T13:30:01Z

@astorm since you're in a weird state I would suggest a complete clean and rebootstrap

MAKE SURE YOU HAVE COMMITTED ANYTHING YOU WANT TO KEEP BEFORE DOING THIS

# from the root of the project
lerna clean -y
git clean -fdx
npm install # This will cause the project to be built and linked by npm scripts

astorm · 2020-05-07T13:48:47Z

@dyladan Thank you for the advice -- I gave that a try and still ran similar issues, and I tried a fresh git clone in a separate directory and ran into similar issues. The fresh checkout makes me think this isn't a problem of the repo being in some bad state, but rather there's some you'all take for granted about your environments that I'm not aware of .

@dyladan question -- I noticed in the sample command you gave me that you're running lerna globally. I don't have lerna installed globally and was relying on the version installed in the project. Could you let me know what version of lerna you have installed globally so I can attempt to match your environment? (also -- what version of node are you using?)

dyladan · 2020-05-07T14:11:01Z

Oh sorry yes I do have lerna installed globally. The issue you're seeing looks like a compilation issue. It's possible that the @types/node package updated and you just happened to be the unlucky person to be affected first.

$ lerna --version
3.20.2
$ node --version
v12.14.1

dyladan · 2020-05-07T14:18:54Z

I am able to reproduce your issue on a complete rebuild.

astorm · 2020-05-07T14:21:15Z

I am able to reproduce your issue on a complete rebuild.

Yay, I am not any more insane that any other software engineer :) And I learned the project's CircleCI tests don't include a full compile cycle, so that's a good thing to know.

Regardless of these build issues, this PR is ready for review.

dyladan · 2020-05-07T14:23:51Z

The CI uses a cached set of dependencies because the dep install takes so long and takes so many resources. It's unfortunate, but it is the way it is. Changing any package.json causes the cache key to change and a full build in CI.

dyladan · 2020-05-07T14:29:04Z

packages/opentelemetry-exporter-prometheus/src/prometheus.ts

@@ -184,7 +184,9 @@ export class PrometheusExporter implements MetricExporter {
     */
    if (metric instanceof Counter) {
      metric.remove(
-        ...record.descriptor.labelKeys.map(k => record.labels[k].toString())
+        ...record.descriptor.labelKeys.map(k =>


In what cases would record.labels[k] be missing?

In my manual testing last night this change prevented an error being thrown when a user instantiates a counter with a label key

const monotonicCounter = meter.createCounter('monotonic_counter', { monotonic: true, labelKeys: ['pid'], description: 'Example of a monotonic counter', });

but then fails to provide a value for that key.

monotonicCounter.add(1, {}) monotonicCounter.add(1)

@dyladan With my build issues sorted/understood I can (depending on how your conversation with @mayurkale22 goes) either add tests that make the use-case here clear or revert this.

Ah I understand. Instead of falling back to an empty string, I think I would prefer a filter on the list.

metric.remove( ...record.descriptor.labelKeys .filter(k => record.labels[k] != null) .map(k => record.labels[k].toString()) );

This is clever solution but feel like it won't work as expected.

AFAIK prom-client will throw "Invalid number of arguments" exception if length of keys != length of values. See: https://github.com/siimon/prom-client/blob/master/lib/util.js#L34

One option is to fall back on "value missing or unknown" as a default value when the corresponding value is not defined in any given key(s), similar to the description field. WDYT?

Option 2: Instead of blindly attaching our Labelkeys to prom-client's labelNames, we can filter the keys based on valid value.

This is what python has implemented: https://github.com/open-telemetry/opentelemetry-python/blob/master/ext/opentelemetry-ext-prometheus/src/opentelemetry/ext/prometheus/__init__.py#L146-L150

Thank you for your feedback @mayurkale22

WDYT?

IT I've been wrangled into an bug fix that is just outside the scope of my original PR -- but I can live with that :)

Re: option 2 -- when you say

Option 2: Instead of blindly attaching our Labelkeys to prom-client's labelNames, we can filter the keys based on valid value.

My interpretation of this is it's a suggestion that, when it comes time to create the Prometheus metric, we look at the keys and values of the passed in Open Telemetry metric, remove any keys with "non-valid" values (undefined, null, -- others?) and create the Prometheus metric with this new, smaller, set of keys.

If that's the suggestion -- I don't think this is the right course of action. Label keys seem like a fundamental part of a metric. That is -- a metric with the keys [foo, bar, baz] seems like a different metric than one with the keys [foo, bar]. Removing keys doesn't seems like the right course of action.

Give than, Option 1 seems like the better approach.

One option is to fall back on "value missing or unknown" as a default value when the corresponding value is not defined in any given key(s),

You didn't indicate whether you thought this value should be added when handling the Prometheus metric, or when recording the Open Telemetry metric. My assumption is the former, as having this extra work happen every time a metric is recorded would be excessive.

Given all that: I intend to change how Prometheus metrics are instantiated. If a value isn't present for a specific key, I will use a constant string of value missing for its value. I will add tests to cover this case. I'll check the spec for what constitutes a valid values, and make judgment call if there are ambiguities there.

@dyladan would like you know your thoughts on this?

IT I've been wrangled into an bug fix that is just outside the scope of my original PR

Perhaps we can merge this PR and address prometheus exporter issue in the separate PR (btw, this won't make master branch unstable but we need to apply fix before next release). If we decide to merge, I would suggest to revert prometheus related to changes from this PR.

Think I would rather see it as two separate PRs simply for the purpose of having better history later when we have to go spelunking through PRs to discover why decisions were made. Not a strong preference though. Agree the prom changes should be reverted if this is going to merge without a proper fix.

dyladan · 2020-05-07T14:33:59Z

packages/opentelemetry-metrics/src/Metric.ts

@@ -133,7 +133,7 @@ export class CounterMetric extends Metric<BoundCounter> implements api.Counter {
   * @param labels key-values pairs that are associated with a specific metric
   *     that you want to record.
   */
-  add(value: number, labels: api.Labels) {
+  add(value: number, labels: api.Labels = {}) {


@mayurkale22 not sure why you think the prometheus exporter would fail on that line. Can you explain? I'm hesitant to approve changes to the _registerMetric routine in the prometheus exporter because the prom-client has some surprising behavior, and that is the logic we use to destroy and recreate the counters with the new values.

dyladan

Thanks

mayurkale22 · 2020-05-11T17:41:56Z

@open-telemetry/javascript-approvers We need more reviews for this one!

obecny

lgtm, one minor comment

packages/opentelemetry-metrics/test/Meter.test.ts

packages/opentelemetry-metrics/src/Metric.ts

* fix: homepage links * fix: add homepage for redis-4 Co-authored-by: Amir Blum <[email protected]>

Make labels optional for add

2cb9dae

astorm requested review from bg451, dyladan, markwolff, mayurkale22, obecny, OlivierAlbertini, rochdev and vmarchaud as code owners May 7, 2020 00:24

mayurkale22 reviewed May 7, 2020

View reviewed changes

mayurkale22 added bug Something isn't working size/S Denotes a PR that changes 10-29 lines, ignoring generated files. labels May 7, 2020

astorm marked this pull request as draft May 7, 2020 01:15

astorm added 2 commits May 6, 2020 18:24

updating interfaces, and MeasureMetric

abf279c

lint

0c4c82b

for a metri defined with label keys, but without metric values

276fedf

whatever you say lint

fb000c1

astorm marked this pull request as ready for review May 7, 2020 13:26

dyladan mentioned this pull request May 7, 2020

Project failing to build #1034

Closed

dyladan added the API label May 7, 2020

dyladan added the breaking label May 7, 2020

dyladan reviewed May 7, 2020

View reviewed changes

Merge branch 'master' into astorm/labels-optional

9928ba7

astorm marked this pull request as draft May 8, 2020 15:08

reverting "getValues" changes

15a1cf7

mayurkale22 approved these changes May 8, 2020

View reviewed changes

dyladan mentioned this pull request May 8, 2020

Remove prom-client from prometheus exporter #1039

Closed

astorm marked this pull request as ready for review May 8, 2020 19:04

Merge branch 'master' into astorm/labels-optional

649a4b8

dyladan approved these changes May 8, 2020

View reviewed changes

Merge branch 'master' into astorm/labels-optional

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obecny approved these changes May 13, 2020

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dyladan added the Merge:LGTM This PR is ready to be merged by a Maintainer (has enough valid approvals, successful build, etc.) label May 13, 2020

obecny reviewed May 13, 2020

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astorm added 2 commits May 13, 2020 07:29

adding shoulder, fixing param

38cb3a9

Merge branch 'master' into astorm/labels-optional

ffd2593

dyladan removed the Merge:LGTM This PR is ready to be merged by a Maintainer (has enough valid approvals, successful build, etc.) label May 13, 2020

Merge branch 'master' into astorm/labels-optional

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mayurkale22 merged commit 48de7ff into open-telemetry:master May 13, 2020

dyladan mentioned this pull request May 14, 2020

Count Metrics: Cannot convert undefined or null to object #1031

Closed

dyladan added a commit to dyladan/opentelemetry-js that referenced this pull request Sep 9, 2022

Make Labels Optional for CounterMetric::add (open-telemetry#1032)

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pichlermarc pushed a commit to dynatrace-oss-contrib/opentelemetry-js that referenced this pull request Dec 15, 2023

docs: fix homepage links (open-telemetry#1032)

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* fix: homepage links * fix: add homepage for redis-4 Co-authored-by: Amir Blum <[email protected]>

martinkuba pushed a commit to martinkuba/opentelemetry-js that referenced this pull request Mar 13, 2024

docs: fix homepage links (open-telemetry#1032)

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* fix: homepage links * fix: add homepage for redis-4 Co-authored-by: Amir Blum <[email protected]>

martinkuba pushed a commit to martinkuba/opentelemetry-js that referenced this pull request Mar 16, 2024

docs: fix homepage links (open-telemetry#1032)

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* fix: homepage links * fix: add homepage for redis-4 Co-authored-by: Amir Blum <[email protected]>

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Make Labels Optional for CounterMetric::add #1032

Make Labels Optional for CounterMetric::add #1032

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Make Labels Optional for CounterMetric::add #1032

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astorm commented May 7, 2020

Which problem is this PR solving?

Short description of the changes

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