Silencing metrics / Skip publishing metrics based on an environment variable

[zirkelc]

Hi,

I wanted to know if it is possible to silence metrics based on an environment variable in the same way it is possible to silence logs.

Basically, I want to omit publishing metrics if the environment is not production. Ideally, that should be controllable with an env var.

[dreamorosi]

Hi @zirkelc, at the moment this is not possible.

We have equivalent settings for Logger (as you pointed out), Tracer, and Idempotency - basically all the other utilities with side effects - but this feature request has never come up.

I think we could either add a POWERTOOLS_METRICS_DISABLED environment variable (name TBD) or add this to the existing POWERTOOLS_DEV env variable.

For consistency & ease of usage we should probably add both. This would be similar to what already happens for Tracer.

This is something we should be able to add relatively quickly, even for the next release. I just would like to allow one or two days max for other maintainers to give an opinion on the name of the environment variable, since it'll be a feature that will likely be adopted by other Powertools for AWS Lambda runtimes.

cc @aws-powertools/lambda-python-core, @aws-powertools/lambda-dotnet-core

[zirkelc]

Thanks for pointing this out, I hadn't thought to check the other repos. I'm not sure if there is a consensus on this issue, but I infer from the labels that a PR would be accepted? I could submit one even if it was written in TypeScript and not Python.

[dreamorosi]

Thanks for your patience, I have brought this up with the team during our internal weekly planning meeting and we have agreed to move forward with the feature, so a PR would be welcome.

I'm converting this to an issue so we can track the item. In terms of implementation I think the easiest and less invasive way of implementing this would be to disable the utility by making the Metrics.publishStoredMetrics() a no-op when certain conditions are met.

Specifically:

• by default, Metrics is enabled (current behavior)
• if the POWERTOOLS_METRICS_DISABLED env variable is present and truthy when the Metrics class is instantiated, then it becomes disabled
• if dev mode is enabled by means of POWERTOOLS_DEV which can be checked with this method, when the Metrics class is instantiated, then it also becomes disabled
• If POWERTOOLS_METRICS_DISABLED is set to false, and dev mode is enabled, then POWERTOOLS_METRICS_DISABLED takes precedence and the utility stays enabled.

This last point, while slightly counter intuitive, provides an escape hatch for those who want to use POWERTOOLS_DEV for other utilities/features but want to keep Metrics enabled.

--

If you have any questions during the implementation, please let me know.

[leandrodamascena]

I'll wait for TypeScript to be implemented before moving forward with Python.

Thanks for working on this @zirkelc.

[dreamorosi]

I've opened the issue (#3329), whenever you start working on it please leave a comment there so I can assign it to you for tracking purposes - GitHub doesn't allow me to assign issues to members of the community who haven't interacted with an issue first.

Also we are planning a release on Thursday end of the day / Friday morning, just mentioning it to manage expectations. If the PR is in by Wednesday end of the day, we'll do our best to review it and merge it before the release - otherwise it'll have to wait for the next one which will likely be the first week of December.

[zirkelc]

I added a comment so you can assign it to me.

[dreamorosi]

The change has been merged in #3351 and will be included in the next release.

Thank you again @zirkelc for bringing this up and for the contribution!