Document available configuration

[iNikem]

I was unable to find any documentation about supported configuration options. io.opentelemetry.auto.config.Config class has quite a lot of options that can be of interest to end-users.

[mnottheone]

We need these docs about config parameters. My understanding is 1255 and 479 has been released in 0.4.0. Docs doesn't reflect these parameters.

Below should set sampler probability to 0.2

java -javaagent:path/to/opentelemetry-auto-all.jar -Dota.exporter=zipkin -Dotel.config.sampler.probability=0.2 -jar myapp.jar

If yes, should we update the docs?

[iNikem]

Of course we should update the docs. This issue is exactly about that :) Do you care to submit a PR and kick it off?

[trask]

I split out a more targeted issue specifically to document the standard OpenTelemetry env var / system properties that we support #666.

[breedx-splk]

#666 has been closed for a while, and I feel like the docs are pretty good at this point. Is there any more to do on this one?

[iNikem]

@breedx-splk We don't have any documentation for instrumentation-specific configurations like otel.instrumentation.kafka.client-propagation

[vasireddy99]

Just as the label is removed to this issue. still is our only AI waiting for to declare metrics as GA ?. looking at it from milestone project 😃

[mateuszrzeszutek]

Hey @vasireddy99,
That milestone project was about the javaagent GA, we haven't exactly been using it recently, so I just closed it - it was not related to the metrics API/SDK at all, it might've been a bit confusing.
As for the metrics, the Java API & SDK artifacts are stable (the SDK was declared stable recently in v1.14.0); the metrics spec is also stable for the most part, with a couple things that are still being worked on (see https://opentelemetry.io/docs/reference/specification/metrics/sdk/)

[trask]

there's a script now to find all configuration options: https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/.github/scripts/find-all-config-properties.sh

some of the general ones are documented at https://opentelemetry.io/docs/instrumentation/java/automatic/agent-config/#common-instrumentation-configuration

and some of the specific ones are documented in the instrumentation module's README, e.g. https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/instrumentation/graphql-java-12.0/javaagent/README.md

[breedx-splk]

@trask IIRC there are a number of config items that are "composed" (for lack of a better term right now), where the end configs are based on a prefix or something, right? I didn't bother to look for an example, but I swear I've seen that. Won't this miss those?

Not to harsh on the script (it's great!) tho I do think we'd get a lot of mileage out of a more concrete/central config names class or something.

[mateuszrzeszutek]

@trask IIRC there are a number of config items that are "composed" (for lack of a better term right now), where the end configs are based on a prefix or something, right? I didn't bother to look for an example, but I swear I've seen that. Won't this miss those?

I think that the instrumentation enabled property (otel.instrumentation.<name>.enabled) is probably the only example of this; I think I've removed all other config "templates" when I was working on simplifying/deprecating Config