This article describes the networking metrics built-in for System.Net produced using the System.Diagnostics.Metrics API. For a listing of metrics based on the alternate EventCounters API, see Well-known EventCounters in .NET.
System.Net.NameResolution
The System.Net.NameResolution
metrics report DNS name resolution from Dns:
dns.lookup.duration
Name Instrument Type Unit Description dns.lookup.duration
Histogram s
Measures the time taken to perform a DNS lookup. Attribute Type Description Examples Presence dns.question.name
string
The name being queried. www.example.com
; dot.net
Always error.type
string
A well-known error string or the full type name of an exception that occurred. host_not_found
; System.Net.Sockets.SocketException
If an error occurred
This metric measures the time take to make DNS requests. These requests can occur by calling methods on Dns or indirectly within higher level APIs on types such as HttpClient.
Most errors when doing a DNS lookup throw a SocketException. To better disambiguate the common error cases, socket exceptions with specific SocketErrorCode are given explicit error names in error.type
:
Socket exceptions with any other SocketError
value are reported as System.Net.Sockets.SocketException
.
When using OpenTelemetry, the default buckets for this metric are set to [ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ].
Available starting in: .NET 8.
System.Net.Http
The System.Net.Http
metrics report HTTP request and connection information from System.Net.Http:
http.client.open_connections
http.client.connection.duration
http.client.request.duration
http.client.request.time_in_queue
http.client.active_requests
http.client.open_connections
Attribute Type Description Examples Presence http.connection.state
string
State of HTTP connection in the HTTP connection pool. active
; idle
Always network.protocol.version
string
Version of the HTTP protocol used. 1.1
; 2
Always server.address
string
Host identifier of the "URI origin" HTTP request is sent to. example.com
Always server.port
int
Port identifier of the "URI origin" HTTP request is sent to. 80
; 8080
; 443
If not default (80
for http
scheme, 443
for https
) network.peer.address
string
Peer IP address of the socket connection. 10.5.3.2
Always url.scheme
string
The URI scheme component identifying the used protocol. http
; https
; ftp
Always
HttpClient, when configured to use the default SocketsHttpHandler, maintains a cached pool of network connections for sending HTTP messages. This metric counts how many connections are currently in the pool. Active connections are handling active requests. Active connects could be transmitting data or awaiting the client or server. Idle connections aren't handling any requests, but are left open so that future requests can be handled more quickly.
Available starting in: .NET 8.
Metric:http.client.connection.duration
Name Instrument Type Unit (UCUM) Description http.client.connection.duration
Histogram s
The duration of successfully established outbound HTTP connections. Attribute Type Description Examples Presence network.protocol.version
string
Version of the HTTP protocol used. 1.1
; 2
Always server.address
string
Host identifier of the "URI origin" HTTP request is sent to. example.com
Always server.port
int
Port identifier of the "URI origin" HTTP request is sent to. 80
; 8080
; 443
If not default (80
for http
scheme, 443
for https
) network.peer.address
string
IP address of the socket connection. 10.5.3.2
Always url.scheme
string
The URI scheme component identifying the used protocol. http
; https
; ftp
Always
This metric is only captured when HttpClient is configured to use the default SocketsHttpHandler.
As this metric is tracking the connection duration, and ideally http connections are used for multiple requests, the buckets should be longer than those used for request durations. For example, using [ 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 30, 60, 120, 300 ] provides an upper bucket of 5 mins.
Available starting in: .NET 8.
Metric:http.client.request.duration
Attribute Type Description Examples Presence error.type
string
Request failure reason: one of the HTTP request errors in snake_case, or a full exception type, or an HTTP 4xx/5xx status code. System.Threading.Tasks.TaskCanceledException
; name_resolution_error
; secure_connection_error
; 404
If request has failed. http.request.method
string
HTTP request method. GET
; POST
; HEAD
; _OTHER
[2] Always http.response.status_code
int
HTTP response status code. 200
If response was received. network.protocol.version
string
Version of the HTTP protocol used. 1.1
; 2
If response was received. server.address
string
Host identifier of the "URI origin" HTTP request is sent to. example.com
Always server.port
int
Port identifier of the "URI origin" HTTP request is sent to. 80
; 8080
; 443
Depends on .NET version. [3] url.scheme
string
The URI scheme component identifying the used protocol. http
; https
; ftp
Always
[1] error.type
: If the request has failed, the value is set to one of the following:
500
.Unknown
, the enum value in snake case, for example, name_resolution_error
.[2] http.request.method
: http.request.method
:** The value contains the method name, if the method is one of the well-known methods listed in RFC9110; otherwise the value is _OTHER
. The user-provided method names will be mapped to known names in a case-insensitive manner. For example, if the user provides the name GeT
, it will be mapped to GET
.
[3] server.port
: The Presence of the value is version-dependent:
80
for http
scheme, 443
for https
)HTTP client request duration measures the time the underlying client handler takes to complete the request. Completing the request includes the time up to reading response headers from the network stream. It doesn't include the time spent reading the response body.
When using OpenTelemetry, the default buckets for this metric are set to [ 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10 ].
Available starting in: .NET 8.
Metric:http.client.request.time_in_queue
Attribute Type Description Examples Presence http.request.method
string
HTTP request method. GET
; POST
; HEAD
Always network.protocol.version
string
Version of the HTTP protocol used. 1.1
; 2
Always server.address
string
Host identifier of the "URI origin" HTTP request is sent to. example.com
Always server.port
int
Port identifier of the "URI origin" HTTP request is sent to. 80
; 8080
; 443
If not default (80
for http
scheme, 443
for https
) url.scheme
string
The URI scheme component identifying the used protocol. http
; https
; ftp
Always
HttpClient, when configured to use the default SocketsHttpHandler, sends HTTP requests using a pool of network connections. If all connections are busy handling other requests, new requests are placed in a queue and wait until a network connection is available for use. This instrument measures the amount of time HTTP requests spend waiting in that queue, prior to anything being sent across the network.
Available starting in: .NET 8.
Metric:http.client.active_requests
Attribute Type Description Examples Presence http.request.method
string
HTTP request method. GET
; POST
; HEAD
Always server.address
string
Host identifier of the "URI origin" HTTP request is sent to. example.com
Always server.port
int
Port identifier of the "URI origin" HTTP request is sent to. 80
; 8080
; 443
If not default (80
for http
scheme, 443
for https
) url.scheme
string
The URI scheme component identifying the used protocol. http
; https
; ftp
Always
This metric counts how many requests are considered active. Requests are active for the same time period that is measured by the http.client.request.duration instrument.
Available starting in: .NET 8.
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