General attributes

Status: Experimental

The attributes described in this section are not specific to a particular operation but rather generic. They may be used in any Span they apply to. Particular operations may refer to or require some of these attributes.

General network connection attributes

These attributes may be used for any network related operation. The net.peer.* attributes describe properties of the remote end of the network connection (usually the transport-layer peer, e.g. the node to which a TCP connection was established), while the* properties describe the local end. In an ideal situation, not accounting for proxies, multiple IP addresses or host names, the net.peer.* properties of a client are equal to the* properties of the server and vice versa.

Attribute Type Description Examples Required
net.transport string Transport protocol used. See note below. ip_tcp No
net.peer.ip string Remote address of the peer (dotted decimal for IPv4 or RFC5952 for IPv6) No
net.peer.port int Remote port number. 80; 8080; 443 No string Remote hostname or similar, see note below. No string Like net.peer.ip but for the host IP. Useful in case of a multi-IP host. No int Like net.peer.port but for the host port. 35555 No string Local hostname or similar, see note below. localhost No string The internet connection type currently being used by the host. wifi No string This describes more details regarding the connection.type. It may be the type of cell technology connection, but it could be used for describing details about a wifi connection. LTE No string The name of the mobile carrier. sprint No string The mobile carrier country code. 310 No string The mobile carrier network code. 001 No string The ISO 3166-1 alpha-2 2-character country code associated with the mobile carrier network. DE No

net.transport MUST be one of the following:

Value Description
ip_tcp ip_tcp
ip_udp ip_udp
ip Another IP-based protocol
unix Unix Domain socket. See below.
pipe Named or anonymous pipe. See note below.
inproc In-process communication. [1]
other Something else (non IP-based).

[1]: Signals that there is only in-process communication not using a “real” network protocol in cases where network attributes would normally be expected. Usually all other network attributes can be left out in that case. MUST be one of the following or, if none of the listed values apply, a custom value:

Value Description
wifi wifi
wired wired
cell cell
unavailable unavailable
unknown unknown MUST be one of the following or, if none of the listed values apply, a custom value:

Value Description
gprs GPRS
edge EDGE
umts UMTS
cdma CDMA
evdo_0 EVDO Rel. 0
evdo_a EVDO Rev. A
cdma2000_1xrtt CDMA2000 1XRTT
hsdpa HSDPA
hsupa HSUPA
hspa HSPA
iden IDEN
evdo_b EVDO Rev. B
lte LTE
ehrpd EHRPD
hspap HSPAP
gsm GSM
td_scdma TD-SCDMA
iwlan IWLAN
nr 5G NR (New Radio)
nrnsa 5G NRNSA (New Radio Non-Standalone)
lte_ca LTE CA

For Unix and pipe, since the connection goes over the file system instead of being directly to a known peer, is the only attribute that usually makes sense (see description of below).

net.*.name attributes

For IP-based communication, the name should be a DNS host name. For, this should be the name that was used to look up the IP address that was connected to (i.e., matching net.peer.ip if that one is set; e.g., "" if connecting to an URL If only the IP address but no host name is available, reverse-lookup of the IP may optionally be used to obtain it. should be the host name of the local host, preferably the one that the peer used to connect for the current operation. If that is not known, a public hostname should be preferred over a private one. However, in that case it may be redundant with information already contained in resources and may be left out. It will usually not make sense to use reverse-lookup to obtain, as that would result in static information that is better stored as resource information.

If net.transport is "unix" or "pipe", the absolute path to the file representing it should be used as ( doesn’t make sense in that context). If there is no such file (e.g., anonymous pipe), the name should explicitly be set to the empty string to distinguish it from the case where the name is just unknown or not covered by the instrumentation.

General remote service attributes

This attribute may be used for any operation that accesses some remote service. Users can define what the name of a service is based on their particular semantics in their distributed system. Instrumentations SHOULD provide a way for users to configure this name.

Attribute Type Description Examples Required
peer.service string The of the remote service. SHOULD be equal to the actual resource attribute of the remote service if any. AuthTokenCache No

Examples of peer.service that users may specify:

  • A Redis cache of auth tokens as peer.service="AuthTokenCache".
  • A gRPC service rpc.service="io.opentelemetry.AuthService" may be hosted in both a gateway, peer.service="ExternalApiService" and a backend, peer.service="AuthService".

General identity attributes

These attributes may be used for any operation with an authenticated and/or authorized enduser.

Attribute Type Description Examples Required string Username or client_id extracted from the access token or Authorization header in the inbound request from outside the system. username No
enduser.role string Actual/assumed role the client is making the request under extracted from token or application security context. admin No
enduser.scope string Scopes or granted authorities the client currently possesses extracted from token or application security context. The value would come from the scope associated with an OAuth 2.0 Access Token or an attribute value in a SAML 2.0 Assertion. read:message, write:files No

These attributes describe the authenticated user driving the user agent making requests to the instrumented system. It is expected this information would be propagated unchanged from node-to-node within the system using the Baggage mechanism. These attributes should not be used to record system-to-system authentication attributes.

Examples of where the value is extracted from:

Authentication protocol Field or description
HTTP Basic/Digest Authentication username
OAuth 2.0 Bearer Token OAuth 2.0 Client Identifier value from client_id for the OAuth 2.0 Client Credentials Grant flow and subject or username from get token info response for other flows using opaque tokens.
OpenID Connect 1.0 IDToken sub
SAML 2.0 Assertion urn:oasis:names:tc:SAML:2.0:assertion:Subject
Kerberos PrincipalName
Framework Field or description
JavaEE/JakartaEE Servlet javax.servlet.http.HttpServletRequest.getUserPrincipal()
Windows Communication Foundation ServiceSecurityContext.Current.PrimaryIdentity

Given the sensitive nature of this information, SDKs and exporters SHOULD drop these attributes by default and then provide a configuration parameter to turn on retention for use cases where the information is required and would not violate any policies or regulations.

General thread attributes

These attributes may be used for any operation to store information about a thread that started a span.

Attribute Type Description Examples Required int Current “managed” thread ID (as opposed to OS thread ID). 42 No string Current thread name. main No

Examples of where and can be extracted from:

Launguage or platform
JVM Thread.currentThread().getId() Thread.currentThread().getName()
.NET Thread.CurrentThread.ManagedThreadId Thread.CurrentThread.Name
Python threading.current_thread().ident threading.current_thread().name
C++ std::this_thread::get_id()
Erlang erlang:system_info(scheduler_id)

Source Code Attributes

Often a span is closely tied to a certain unit of code that is logically responsible for handling the operation that the span describes (usually the method that starts the span). For an HTTP server span, this would be the function that handles the incoming request, for example. The attributes listed below allow to report this unit of code and therefore to provide more context about the span.

Attribute Type Description Examples Required
code.function string The method or function name, or equivalent (usually rightmost part of the code unit’s name). serveRequest No
code.namespace string The “namespace” within which code.function is defined. Usually the qualified class or module name, such that code.namespace + some separator + code.function form a unique identifier for the code unit. com.example.MyHttpService No
code.filepath string The source code file name that identifies the code unit as uniquely as possible (preferably an absolute file path). /usr/local/MyApplication/content_root/app/index.php No
code.lineno int The line number in code.filepath best representing the operation. It SHOULD point within the code unit named in code.function. 42 No