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.

Server, client and shared network attributes

These attributes may be used to describe the client and server in a connection-based network interaction where there is one side that initiates the connection (the client is the side that initiates the connection). This covers all TCP network interactions since TCP is connection-based and one side initiates the connection (an exception is made for peer-to-peer communication over TCP where the “user-facing” surface of the protocol / API does not expose a clear notion of client and server). This also covers UDP network interactions where one side initiates the interaction, e.g. QUIC (HTTP/3) and DNS.

In an ideal situation, not accounting for proxies, multiple IP addresses or host names, the server.* attributes are the same on the client and server.

Address and port attributes

For all IP-based protocols, the “address” should be just the IP-level address. Protocol-specific parts of an address are split into other attributes (when applicable) such as “port” attributes for TCP and UDP. If such transport-specific information is collected and the attribute name does not already uniquely identify the transport, then setting network.transport is especially encouraged.

Server attributes

Warning Attributes in this section are in use by the HTTP semantic conventions. Once the HTTP semantic conventions are declared stable, changes to the attributes in this section will only be allowed if they do not cause breaking changes to HTTP semantic conventions.

Attribute Type Description Examples Requirement Level
server.address string Server address - domain name if available without reverse DNS lookup, otherwise IP address or Unix domain socket name. [1] example.com; 10.1.2.80; /tmp/my.sock Recommended
server.port int Server port number. [2] 80; 8080; 443 Recommended

[1]: When observed from the client side, and when communicating through an intermediary, server.address SHOULD represent the server address behind any intermediaries (e.g. proxies) if it’s available.

[2]: When observed from the client side, and when communicating through an intermediary, server.port SHOULD represent the server port behind any intermediaries (e.g. proxies) if it’s available.

server.address and server.port represent logical server name and port. Semantic conventions that refer to these attributes SHOULD specify what these attributes mean in their context.

server.address

For IP-based communication, the name should be a DNS host name of the service. On client side it matches remote service name, on server side, it represents local service name as seen externally on clients.

When connecting to an URL https://example.com/foo, server.address matches "example.com" on both client and server side.

On client side, it’s usually passed in form of URL, connection string, host name, etc. Sometimes host name is only available to instrumentation as a string which may contain DNS name or IP address. server.address SHOULD be set to the available known hostname (e.g., "127.0.0.1" if connecting to an URL https://127.0.0.1/foo).

If only IP address is available, it should be populated on server.address. Reverse DNS lookup SHOULD NOT be used to obtain DNS name.

If network.transport is "pipe", the absolute path to the file representing it should be used as server.address. 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.

For Unix domain socket, server.address attribute represents remote endpoint address on the client side and local endpoint address on the server side.

Client attributes

Warning Attributes in this section are in use by the HTTP semantic conventions. Once the HTTP semantic conventions are declared stable, changes to the attributes in this section will only be allowed if they do not cause breaking changes to HTTP semantic conventions.

Attribute Type Description Examples Requirement Level
client.address string Client address - domain name if available without reverse DNS lookup, otherwise IP address or Unix domain socket name. [1] client.example.com; 10.1.2.80; /tmp/my.sock Recommended
client.port int Client port number. [2] 65123 Recommended

[1]: When observed from the server side, and when communicating through an intermediary, client.address SHOULD represent the client address behind any intermediaries (e.g. proxies) if it’s available.

[2]: When observed from the server side, and when communicating through an intermediary, client.port SHOULD represent the client port behind any intermediaries (e.g. proxies) if it’s available.

Source and destination attributes

These attributes may be used to describe the sender and receiver of a network exchange/packet. These should be used when there is no client/server relationship between the two sides, or when that relationship is unknown. This covers low-level network interactions (e.g. packet tracing) where you don’t know if there was a connection or which side initiated it. This also covers unidirectional UDP flows and peer-to-peer communication where the “user-facing” surface of the protocol / API does not expose a clear notion of client and server.

Source

Attribute Type Description Examples Requirement Level
source.address string Source address - domain name if available without reverse DNS lookup, otherwise IP address or Unix domain socket name. [1] source.example.com; 10.1.2.80; /tmp/my.sock Recommended
source.port int Source port number 3389; 2888 Recommended

[1]: When observed from the destination side, and when communicating through an intermediary, source.address SHOULD represent the source address behind any intermediaries (e.g. proxies) if it’s available.

Destination

Destination fields capture details about the receiver of a network exchange/packet.

Attribute Type Description Examples Requirement Level
destination.address string Destination address - domain name if available without reverse DNS lookup, otherwise IP address or Unix domain socket name. [1] destination.example.com; 10.1.2.80; /tmp/my.sock Recommended
destination.port int Destination port number 3389; 2888 Recommended

[1]: When observed from the source side, and when communicating through an intermediary, destination.address SHOULD represent the destination address behind any intermediaries (e.g. proxies) if it’s available.

Other network attributes

Warning Attributes in this section are in use by the HTTP semantic conventions. Once the HTTP semantic conventions are declared stable, changes to the attributes in this section will only be allowed if they do not cause breaking changes to HTTP semantic conventions.

Attribute Type Description Examples Requirement Level
network.local.address string Local address of the network connection - IP address or Unix domain socket name. 10.1.2.80; /tmp/my.sock Recommended
network.local.port int Local port number of the network connection. 65123 Recommended
network.peer.address string Peer address of the network connection - IP address or Unix domain socket name. 10.1.2.80; /tmp/my.sock Recommended
network.peer.port int Peer port number of the network connection. 65123 Recommended
network.protocol.name string OSI application layer or non-OSI equivalent. [1] amqp; http; mqtt Recommended
network.protocol.version string Version of the protocol specified in network.protocol.name. [2] 3.1.1 Recommended
network.transport string OSI transport layer or inter-process communication method. [3] tcp; udp Recommended
network.type string OSI network layer or non-OSI equivalent. [4] ipv4; ipv6 Recommended

[1]: The value SHOULD be normalized to lowercase.

[2]: network.protocol.version refers to the version of the protocol used and might be different from the protocol client’s version. If the HTTP client used has a version of 0.27.2, but sends HTTP version 1.1, this attribute should be set to 1.1.

[3]: The value SHOULD be normalized to lowercase.

Consider always setting the transport when setting a port number, since a port number is ambiguous without knowing the transport, for example different processes could be listening on TCP port 12345 and UDP port 12345.

[4]: The value SHOULD be normalized to lowercase.

network.transport 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
tcp TCP
udp UDP
pipe Named or anonymous pipe. See note below.
unix Unix domain socket

network.type 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
ipv4 IPv4
ipv6 IPv6

network.peer.* and network.local.* attributes

These attributes identify network peers that are directly connected to each other.

network.peer.address and network.local.address should be IP addresses, Unix domain socket names, or other addresses specific to network type.

Note: Specific structures and methods to obtain socket-level attributes are mentioned here only as examples. Instrumentations would usually use Socket API provided by their environment or sockets implementations.

When connecting using connect(2) (Linux or other POSIX systems / Windows) or bind(2)(Linux or other POSIX systems / Windows) with AF_INET address family, network.peer.address and network.peer.port represent sin_addr and sin_port fields of sockaddr_in structure.

network.peer.address and network.peer.port can be obtained by calling getpeername method (Linux or other POSIX systems / Windows).

network.local.address and network.local.port can be obtained by calling getsockname method (Linux or other POSIX systems / Windows).

Client/server examples using network.peer.*

Note that network.local.* attributes are not included in these examples since they are typically Opt-In.

Simple client/server example
simple.png
Client/server example with reverse proxy
reverse-proxy.png
Client/server example with forward proxy
forward-proxy.png

Network connection and carrier attributes

Attribute Type Description Examples Requirement Level
network.carrier.icc string The ISO 3166-1 alpha-2 2-character country code associated with the mobile carrier network. DE Recommended
network.carrier.mcc string The mobile carrier country code. 310 Recommended
network.carrier.mnc string The mobile carrier network code. 001 Recommended
network.carrier.name string The name of the mobile carrier. sprint Recommended
network.connection.subtype 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 Recommended
network.connection.type string The internet connection type. wifi Recommended

network.connection.subtype 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
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

network.connection.type 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
wifi wifi
wired wired
cell cell
unavailable unavailable
unknown unknown

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

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 Requirement Level
peer.service string The service.name of the remote service. SHOULD be equal to the actual service.name resource attribute of the remote service if any. AuthTokenCache Recommended

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 Requirement Level
enduser.id string Username or client_id extracted from the access token or Authorization header in the inbound request from outside the system. username Recommended
enduser.role string Actual/assumed role the client is making the request under extracted from token or application security context. admin Recommended
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 Recommended

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 enduser.id 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 Requirement Level
thread.daemon boolean Whether the thread is daemon or not. Recommended
thread.id int Current “managed” thread ID (as opposed to OS thread ID). 42 Recommended
thread.name string Current thread name. main Recommended

Examples of where thread.id and thread.name can be extracted from:

Language or platform thread.id thread.name
JVM Thread.currentThread().getId() Thread.currentThread().getName()
.NET Thread.CurrentThread.ManagedThreadId Thread.CurrentThread.Name
Python threading.current_thread().ident threading.current_thread().name
Ruby Thread.current.object_id Thread.current.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 Requirement Level
code.column int The column number in code.filepath best representing the operation. It SHOULD point within the code unit named in code.function. 16 Recommended
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 Recommended
code.function string The method or function name, or equivalent (usually rightmost part of the code unit’s name). serveRequest Recommended
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 Recommended
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 Recommended