Adds support for default attributes #21
Description
A common use case is that users can pass default attributes to instrumentation at different levels, e.g.:
- https://github.com/openzipkin/brave/blob/f89723df407e2b85dd7e6700ab574b4fa5bdae94/brave/src/test/java/brave/features/handler/DefaultTagsTest.java#L32
- https://github.com/openzipkin/zipkin-go/blob/master/middleware/http/server.go#L42
- Allow adding arbitrary tags on span openzipkin/zipkin-js#502
- recoding default tags on server instrumentation openzipkin/zipkin-js#302
We can allow static tags being passed directly from code and also over env vars:
message AgentConfig {
...
// defaultTags accept a map of tags that will be added on every span
map<string, string> defaultTags = 4;
}
Ping @hypertrace/agent-maintainers