NH-58499: poc for backward compatibility for solarwinds_apm

[xuan-cao-swi]

Based on the https://rubydoc.info/gems/solarwinds_apm/SolarWindsAPM/SDK, create opentelemetry-ruby compatible function for custom_metrics as vendor-provided function.

I tested with following scripts

count = 1
while count < 10
  SolarWindsAPM::SDK.increment_metric(:test_name_02, 1, true, 7.7)
  sleep 2
  count+=1
end

# sample metrics
# https://my.na-01.st-ssp.solarwinds.com/136444677275740160/metrics/details?metrics=%5B%7B%22name%22%3A%22test_name_02%22%2C%22aggregateBy%22%3A%22AVG%22%2C%22searchQuery%22%3A%22%22%7D%5D&duration=1800

SolarWindsAPM::SDK.summary_metric('abc', 7.7, 1, true, {} )

More ad-hoc test will be in testbed

[xuan-cao-swi]

Based on conversation, we only reserve the backward/feature of custom metrics.

[cheempz]

Thanks @xuan-cao-swi. It looks like the custom metrics methods are exposed under SolarWindsAPM::SDK, while the rest of our other vendor specific APIs are exposed by SolarWindsAPM::API (see https://github.com/solarwindscloud/swotel-ruby/blob/main/README.md#using-the-solarwindsapm-api). Could you:

• standardize the interface for these to be under API
• add a couple of tests for these, probably easiest in the testbed repo in order to actually verify the metrics
• update this PR description

[cheempz]

One more ask: playing around with SolarWindsAPM::SDK.increment_metric, it seems the return value is false for a successful submission of metrics. Can you look into that?

irb(main):026:0> SolarWindsAPM::SDK.increment_metric('ruby-custom-metric', 1, true, {'color'=>'blue'})
=> false

[xuan-cao-swi]

One more ask: playing around with SolarWindsAPM::SDK.increment_metric, it seems the return value is false for a successful submission of metrics. Can you look into that?

It seems like the error checking logic is wrong. 0 should be successful

[cheempz]

LGTM, thanks @xuan-cao-swi!