Semantic Conventions for HTTP Metrics

Status: Experimental

The conventions described in this section are HTTP specific. When HTTP operations occur, metric events about those operations will be generated and reported to provide insight into the operations. By adding HTTP attributes to metric events it allows for finely tuned filtering.

Disclaimer: These are initial HTTP metric instruments and attributes but more may be added in the future.

HTTP Server

Metric: `http.server.duration`

This metric is required.

Name	Instrument Type	Unit (UCUM)	Description
`http.server.duration`	Histogram	`ms`	Measures the duration of inbound HTTP requests.

Attribute	Type	Description	Examples	Requirement Level
`http.scheme`	string	The URI scheme identifying the used protocol.	`http`; `https`	Required
`http.route`	string	The matched route (path template in the format used by the respective server framework). See note below [1]	`/users/:userID?`; `{controller}/{action}/{id?}`	Conditionally Required: If and only if it’s available
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.host.name`	string	Name of the local HTTP server that received the request. [2]	`localhost`	Required
`net.host.port`	int	Port of the local HTTP server that received the request. [3]	`8080`	Conditionally Required: [4]

[1]: MUST NOT be populated when this is not supported by the HTTP server framework as the route attribute should have low-cardinality and the URI path can NOT substitute it. SHOULD include the application roottrace/semantic_conventions/http.md#http-server-definitions) if there is one.

[2]: Determined by using the first of the following that applies

The primary server nametrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host. MUST only include host identifier.
Host identifier of the request target if it’s sent in absolute-form.
Host identifier of the Host header

SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.

[3]: Determined by using the first of the following that applies

Port identifier of the primary server hosttrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host.
Port identifier of the request target if it’s sent in absolute-form.
Port identifier of the Host header

[4]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

Metric: `http.server.active_requests`

This metric is optional.

Name	Instrument Type	Unit (UCUM)	Description
`http.server.active_requests`	UpDownCounter	`{requests}`	Measures the number of concurrent HTTP requests that are currently in-flight.

Attribute	Type	Description	Examples	Requirement Level
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.scheme`	string	The URI scheme identifying the used protocol.	`http`; `https`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.host.name`	string	Name of the local HTTP server that received the request. [1]	`localhost`	Required
`net.host.port`	int	Port of the local HTTP server that received the request. [2]	`8080`	Conditionally Required: [3]

[1]: Determined by using the first of the following that applies

The primary server nametrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host. MUST only include host identifier.
Host identifier of the request target if it’s sent in absolute-form.
Host identifier of the Host header

SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.

[2]: Determined by using the first of the following that applies

Port identifier of the primary server hosttrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host.
Port identifier of the request target if it’s sent in absolute-form.
Port identifier of the Host header

[3]: If not default (80 for http scheme, 443 for https).

Metric: `http.server.request.size`

This metric is optional.

Name	Instrument Type	Unit (UCUM)	Description
`http.server.request.size`	Histogram	`By`	Measures the size of HTTP request messages (compressed).

Attribute	Type	Description	Examples	Requirement Level
`http.scheme`	string	The URI scheme identifying the used protocol.	`http`; `https`	Required
`http.route`	string	The matched route (path template in the format used by the respective server framework). See note below [1]	`/users/:userID?`; `{controller}/{action}/{id?}`	Conditionally Required: If and only if it’s available
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.host.name`	string	Name of the local HTTP server that received the request. [2]	`localhost`	Required
`net.host.port`	int	Port of the local HTTP server that received the request. [3]	`8080`	Conditionally Required: [4]

[2]: Determined by using the first of the following that applies

The primary server nametrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host. MUST only include host identifier.
Host identifier of the request target if it’s sent in absolute-form.
Host identifier of the Host header

SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.

[3]: Determined by using the first of the following that applies

Port identifier of the primary server hosttrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host.
Port identifier of the request target if it’s sent in absolute-form.
Port identifier of the Host header

[4]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

Metric: `http.server.response.size`

This metric is optional.

Name	Instrument Type	Unit (UCUM)	Description
`http.server.response.size`	Histogram	`By`	Measures the size of HTTP response messages (compressed).

Attribute	Type	Description	Examples	Requirement Level
`http.scheme`	string	The URI scheme identifying the used protocol.	`http`; `https`	Required
`http.route`	string	The matched route (path template in the format used by the respective server framework). See note below [1]	`/users/:userID?`; `{controller}/{action}/{id?}`	Conditionally Required: If and only if it’s available
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.host.name`	string	Name of the local HTTP server that received the request. [2]	`localhost`	Required
`net.host.port`	int	Port of the local HTTP server that received the request. [3]	`8080`	Conditionally Required: [4]

[2]: Determined by using the first of the following that applies

The primary server nametrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host. MUST only include host identifier.
Host identifier of the request target if it’s sent in absolute-form.
Host identifier of the Host header

SHOULD NOT be set if only IP address is available and capturing name would require a reverse DNS lookup.

[3]: Determined by using the first of the following that applies

Port identifier of the primary server hosttrace/semantic_conventions/http.md#http-server-definitions) of the matched virtual host.
Port identifier of the request target if it’s sent in absolute-form.
Port identifier of the Host header

[4]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

HTTP Client

Metric: `http.client.duration`

This metric is required.

Name	Instrument Type	Unit (UCUM)	Description
`http.client.duration`	Histogram	`ms`	Measures the duration of outbound HTTP requests.

Attribute	Type	Description	Examples	Requirement Level
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.peer.name`	string	Host identifier of the “URI origin” HTTP request is sent to. [1]	`example.com`	Required
`net.peer.port`	int	Port identifier of the “URI origin” HTTP request is sent to. [2]	`80`; `8080`; `443`	Conditionally Required: [3]
`net.sock.peer.addr`	string	Remote socket peer address: IPv4 or IPv6 for internet protocols, path for local communication, etc.	`127.0.0.1`; `/tmp/mysql.sock`	Recommended

[1]: Determined by using the first of the following that applies

Host identifier of the request target if it’s sent in absolute-form
Host identifier of the Host header

SHOULD NOT be set if capturing it would require an extra DNS lookup.

[2]: When request target is absolute URI, net.peer.name MUST match URI port identifier, otherwise it MUST match Host header port identifier.

[3]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

Metric: `http.client.request.size`

This metric is optional.

Name	Instrument Type	Unit (UCUM)	Description
`http.client.request.size`	Histogram	`By`	Measures the size of HTTP request messages (compressed).

Attribute	Type	Description	Examples	Requirement Level
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.peer.name`	string	Host identifier of the “URI origin” HTTP request is sent to. [1]	`example.com`	Required
`net.peer.port`	int	Port identifier of the “URI origin” HTTP request is sent to. [2]	`80`; `8080`; `443`	Conditionally Required: [3]
`net.sock.peer.addr`	string	Remote socket peer address: IPv4 or IPv6 for internet protocols, path for local communication, etc.	`127.0.0.1`; `/tmp/mysql.sock`	Recommended

[1]: Determined by using the first of the following that applies

Host identifier of the request target if it’s sent in absolute-form
Host identifier of the Host header

SHOULD NOT be set if capturing it would require an extra DNS lookup.

[2]: When request target is absolute URI, net.peer.name MUST match URI port identifier, otherwise it MUST match Host header port identifier.

[3]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

Metric: `http.client.response.size`

This metric is optional.

Name	Instrument Type	Unit (UCUM)	Description
`http.client.response.size`	Histogram	`By`	Measures the size of HTTP response messages (compressed).

Attribute	Type	Description	Examples	Requirement Level
`http.flavor`	string	Kind of HTTP protocol used.	`1.0`	Recommended
`http.method`	string	HTTP request method.	`GET`; `POST`; `HEAD`	Required
`http.status_code`	int	HTTP response status code.	`200`	Conditionally Required: If and only if one was received/sent.
`net.peer.name`	string	Host identifier of the “URI origin” HTTP request is sent to. [1]	`example.com`	Required
`net.peer.port`	int	Port identifier of the “URI origin” HTTP request is sent to. [2]	`80`; `8080`; `443`	Conditionally Required: [3]
`net.sock.peer.addr`	string	Remote socket peer address: IPv4 or IPv6 for internet protocols, path for local communication, etc.	`127.0.0.1`; `/tmp/mysql.sock`	Recommended

[1]: Determined by using the first of the following that applies

Host identifier of the request target if it’s sent in absolute-form
Host identifier of the Host header

SHOULD NOT be set if capturing it would require an extra DNS lookup.

[2]: When request target is absolute URI, net.peer.name MUST match URI port identifier, otherwise it MUST match Host header port identifier.

[3]: If not default (80 for http scheme, 443 for https).

http.flavor 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
`1.0`	HTTP/1.0
`1.1`	HTTP/1.1
`2.0`	HTTP/2
`3.0`	HTTP/3
`SPDY`	SPDY protocol.
`QUIC`	QUIC protocol.

Semantic Conventions for HTTP Metrics

HTTP Server

Metric: http.server.duration

Metric: http.server.active_requests

Metric: http.server.request.size

Metric: http.server.response.size

HTTP Client

Metric: http.client.duration

Metric: http.client.request.size

Metric: http.client.response.size

Metric: `http.server.duration`

Metric: `http.server.active_requests`

Metric: `http.server.request.size`

Metric: `http.server.response.size`

Metric: `http.client.duration`

Metric: `http.client.request.size`

Metric: `http.client.response.size`