Semantic conventions for Connect RPC

Status: Development

The Semantic Conventions for Connect extend and override the RPC spans and RPC metrics Semantic Conventions that describe common RPC operations attributes in addition to the Semantic Conventions described on this page.

Connect RPC Attributes

rpc.system MUST be set to "connect_rpc".

Below is a table of attributes that SHOULD be included on client and server Connect RPC measurements.

Attribute	Type	Description	Examples	Requirement Level	Stability
rpc.connect_rpc.error_code	string	The error codes of the Connect request. Error codes are always string values.	cancelled; unknown; invalid_argument	Conditionally Required [1]
rpc.connect_rpc.request.metadata.<key>	string[]	Connect request metadata, <key> being the normalized Connect Metadata key (lowercase), the value being the metadata values. [2]	rpc.request.metadata.my-custom-metadata-attribute=["1.2.3.4", "1.2.3.5"]	Opt-In
rpc.connect_rpc.response.metadata.<key>	string[]	Connect response metadata, <key> being the normalized Connect Metadata key (lowercase), the value being the metadata values. [3]	rpc.response.metadata.my-custom-metadata-attribute=["attribute_value"]	Opt-In

[1] rpc.connect_rpc.error_code: If response is not successful and if error code available.

[2] rpc.connect_rpc.request.metadata: Instrumentations SHOULD require an explicit configuration of which metadata values are to be captured. Including all request metadata values can be a security risk - explicit configuration helps avoid leaking sensitive information.

[3] rpc.connect_rpc.response.metadata: Instrumentations SHOULD require an explicit configuration of which metadata values are to be captured. Including all response metadata values can be a security risk - explicit configuration helps avoid leaking sensitive information.

rpc.connect_rpc.error_code has the following list of well-known values. If one of them applies, then the respective value MUST be used; otherwise, a custom value MAY be used.

Value	Description	Stability
aborted	aborted
already_exists	already_exists
cancelled	cancelled
data_loss	data_loss
deadline_exceeded	deadline_exceeded
failed_precondition	failed_precondition
internal	internal
invalid_argument	invalid_argument
not_found	not_found
out_of_range	out_of_range
permission_denied	permission_denied
resource_exhausted	resource_exhausted
unauthenticated	unauthenticated
unavailable	unavailable
unimplemented	unimplemented
unknown	unknown

Connect RPC Status

If rpc.connect_rpc.error_code is set, Span Status MUST be set to Error and left unset in all other cases.