Resource from environment specifies a schema URL

[anuraaga]

I'm not sure if it's a bug or not but I noticed that resource specified with OTEL_RESOURCE_ATTRIBUTES has a schema URL attached.

opentelemetry-java/sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/ResourceConfiguration.java

Line 79 in 666bef3

return Resource.create(resourceAttributes.build(), ResourceAttributes.SCHEMA_URL);

As it's user-provided attributes, I suspect it's not valid to define any schema URL for it as the attributes are unknown. Would it be better to create a schemaless resource for it? In practice, I don't know if it's a big deal as it's correctly pointed out that merging resource of different schemas is undefined behavior

opentelemetry-java/sdk/common/src/main/java/io/opentelemetry/sdk/resources/Resource.java

Line 167 in 666bef3

// currently, behavior is undefined if schema URLs don't match. In the future, we may

But I think it could capture the intent of OTEL_RESOURCE_ATTRIBUTES better.

[anuraaga]

BTW, having an OTEL_RESOURCE_ATTRIBUTES_SCHEMA_URL to allow the user who provided those attributes to also provide a schema could be the most precise implementation, though before that I guess schemaless would be closer than arbitrary schema.