[receiver/httpcheck] Report certificate information

[atoulme]

Component(s)

receiver/httpcheck

Is your feature request related to a problem? Please describe.

The httpcheckreceiver can be used to perform periodic checks of a HTTP endpoint.
The receiver can be enhanced to report certificate information as well.

Describe the solution you'd like

Ideally, the solution should match the metric and method used by the tlscheckreceiver. https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/receiver/tlscheckreceiver

Describe alternatives you've considered

No response

Additional context

No response

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• receiver/httpcheck: @codeboten

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[github-actions]

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[StephanSalas]

I think this could be very useful as both a conditional and optional set of metrics.

E.g. The metrics are only reported for "https" protocol, and only if the user turns it on.

I do wonder if we can approximately copy the metrics enumeration elastic has made:

1. http_cert_status
2. http_cert_cname
3. http_cert_issuedby
4. http_cert_validuntil
5. http_cert_age
6. http_cert_fingerprints

[atoulme]

These are dimensions to metrics, looks like. My proposal is to match what tlscheck receiver offers.

[StephanSalas]

These are dimensions to metrics, looks like. My proposal is to match what tlscheck receiver offers.

Not a bad convention... I think a limited set of metric dimentions to start may be easier / more minimal.

I wouldn't mind taking a stab at this one... it is quite interesting that we have:

1. TLSCheck
2. HttpCheck

As separate components, when this proposal kind of combines the TLSCheck functionality (sort of) with HttpCheck. It seems to be like we could potentially re-use some of the TLSCheck code. I will contemplate some options there...