# Semantic conventions for gRPC Site [llms.txt](/llms.txt) --- **Status**: [Stable][DocumentStatus], unless otherwise specified - [Spans](#spans) - [Client](#client) - [Server](#server) - [Metrics](#metrics) - [Metric: `rpc.server.call.duration` (gRPC)](#metric-rpcservercallduration-grpc) - [Metric: `rpc.client.call.duration` (gRPC)](#metric-rpcclientcallduration-grpc) The Semantic Conventions for [gRPC](https://grpc.io/) extend and override the [RPC Semantic Conventions](README.md). > [!NOTE] > The gRPC project defines its own conventions for [metrics](https://github.com/grpc/proposal/blob/master/A66-otel-stats.md) > and [spans](https://github.com/grpc/proposal/blob/master/A72-open-telemetry-tracing.md). > > Details on how OpenTelemetry spans and metrics defined in this repository > relate to the native gRPC conventions are documented in the > [gRPC compatibility](/docs/specs/semconv/non-normative/compatibility/grpc.md) document. ## Spans ### Client **Status:** ![Stable](https://img.shields.io/badge/-stable-lightgreen) This span represents an outgoing Remote Procedure Call (RPC). `rpc.system.name` MUST be set to `"grpc"` and SHOULD be provided **at span creation time.** **Span name:** refer to the [Span Name](/docs/specs/semconv/rpc/rpc-spans.md#name) section. **Span kind** MUST be `CLIENT`. **Span status**: refer to the [Recording Errors](/docs/specs/semconv/general/recording-errors.md) document for details on how to record span status. See also `rpc.status_code` attribute for the details on which values classify as errors. **Attributes:** | Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values | | --- | --- | --- | --- | --- | --- | | [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The fully-qualified logical name of the method from the RPC interface perspective. [1] | `com.example.ExampleService/exampleMethod`; `EchoService/Echo`; `_OTHER` | | [`rpc.status_code`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The string representation of the [status code](https://github.com/grpc/grpc/blob/v1.75.0/doc/statuscodes.md) returned by the server or generated by the client. [2] | `OK`; `DEADLINE_EXCEEDED`; `UNAVAILABLE` | | [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The Remote Procedure Call (RPC) system. [3] | `grpc` | | [`server.address`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | A string identifying a group of RPC server instances request is sent to. [4] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | | [`error.type`](/docs/specs/semconv/registry/attributes/error.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if the operation failed. | string | Describes a class of error the operation ended with. [5] | `UNKNOWN`; `DEADLINE_EXCEEDED`; `UNIMPLEMENTED`; `INTERNAL`; `UNAVAILABLE`; `DATA_LOSS` | | [`rpc.method_original`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if it's different than `rpc.method`. | string | The original name of the method used by the client. | `com.myservice.EchoService/catchAll`; `com.myservice.EchoService/unknownMethod`; `InvalidMethod` | | [`server.port`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` [6] | int | Server port number. [7] | `50051` | | [`network.peer.address`](/docs/specs/semconv/registry/attributes/network.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | Peer address of the network connection - IP address or UNIX domain socket name. [8] | `10.1.2.80`; `/tmp/my.sock` | | [`network.peer.port`](/docs/specs/semconv/registry/attributes/network.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` If `network.peer.address` is set. | int | Peer port number of the network connection. | `65123` | | [`rpc.request.header.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC request headers, also called [request metadata](https://grpc.io/docs/guides/metadata/). [9] | `["1.2.3.4", "1.2.3.5"]` | | [`rpc.response.header.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC response headers, also called [initial metadata](https://grpc.io/docs/what-is-grpc/core-concepts/#rpc-life-cycle). [10] | `["attribute_value"]` | | [`rpc.response.trailer.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC response trailers, also called [trailing metadata](https://grpc.io/docs/what-is-grpc/core-concepts/#rpc-life-cycle). [11] | `["attribute_value"]` | **[1] `rpc.method`:** The method name MAY have unbounded cardinality in edge or error cases. Some RPC frameworks or libraries provide a fixed set of recognized methods for client stubs and server implementations. Instrumentations for such frameworks MUST set this attribute to the original method name only when the method is recognized by the framework or library. When the method is not recognized, for example, when the server receives a request for a method that is not predefined on the server, or when instrumentation is not able to reliably detect if the method is predefined, the attribute MUST be set to `_OTHER`. If the RPC instrumentation could end up converting valid RPC methods to `_OTHER`, then it SHOULD provide a way to configure the list of recognized RPC methods. The `rpc.method` can be different from the name of any implementing method/function. The `code.function.name` attribute may be used to record the fully-qualified method actually executing the call on the server side, or the RPC client stub method on the client side. **[2] `rpc.status_code`:** All status codes except `OK` SHOULD be considered errors. Instrumentations MAY use additional context or provide configuration options to customize which status codes are considered errors. **[3] `rpc.system.name`:** MUST be set to `grpc`. **[4] `server.address`:** Instrumentations SHOULD populate `server.address` (along with `server.port`) based on the configuration used when creating the gRPC channel and SHOULD NOT use actual network-level connection information for this purpose to ensure low cardinality. Instrumentations MAY parse address and port from the gRPC target string according to the [gRPC Name Resolution specification](https://grpc.github.io/grpc/core/md_doc_naming.html), depending on the scheme used. Or, they MAY use gRPC client APIs that provide this information. If the instrumentation cannot determine a server domain name or another suitable low-cardinality identifier for a group of server instances from the target string, it SHOULD set `server.address` to the entire target string and SHOULD NOT set `server.port`. When the address is an IP address, instrumentations SHOULD NOT do a reverse DNS lookup to obtain a DNS name and SHOULD set `server.address` to the IP address provided. Examples: - Given the target string `grpc.io:50051`, expected attributes: - `server.address`: `"grpc.io"` - `server.port`: `50051` - Given the target string `dns://1.2.3.4/grpc.io:50051`, expected attributes: - `server.address`: `"grpc.io"` - `server.port`: `50051` - Given the target string `unix:///run/containerd/containerd.sock`, expected attributes: - `server.address`: `"/run/containerd/containerd.sock"` - `server.port`: not set - Given the target string `zk://zookeeper:2181/my-server`, expected attributes: - `server.address`: `"zk://zookeeper:2181/my-server"` - `server.port`: not set - Given the target string `ipv4:198.51.100.123:50051,198.51.100.124:50051`, expected attributes: - `server.address`: `"ipv4:198.51.100.123:50051,198.51.100.124:50051"` - `server.port`: not set **[5] `error.type`:** If the RPC fails with an error before status code is returned, `error.type` SHOULD be set to the exception type (its fully-qualified class name, if applicable) or a component-specific, low cardinality error identifier. If a status code is returned and it indicates an error, `error.type` SHOULD be set to that status code. Check system-specific conventions for the details on which values of `rpc.status_code` are considered errors. The `error.type` value SHOULD be predictable and SHOULD have low cardinality. Instrumentations SHOULD document the list of errors they report. If the request has completed successfully, instrumentations SHOULD NOT set `error.type`. **[6] `server.port`:** If and only if the port is available and `server.address` is set. **[7] `server.port`:** See the `server.address` for details on parsing the target string. **[8] `network.peer.address`:** If a RPC involved multiple network calls (for example retries), the last contacted address SHOULD be used. **[9] `rpc.request.header.`:** `` is the normalized header name (lowercase), the value is the header values. Instrumentations SHOULD require an explicit configuration of which headers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a header `my-custom-key` with value `["1.2.3.4", "1.2.3.5"]` SHOULD be recorded as the `rpc.request.header.my-custom-key` attribute with value `["1.2.3.4", "1.2.3.5"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to headers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. **[10] `rpc.response.header.`:** `` is the normalized header name (lowercase), the value is the header values. Instrumentations SHOULD require an explicit configuration of which headers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a header `my-custom-key` with value `["attribute_value"]` SHOULD be recorded as the `rpc.response.header.my-custom-key` attribute with value `["attribute_value"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to headers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. **[11] `rpc.response.trailer.`:** `` is the normalized trailer name (lowercase), the value is the trailer values. Instrumentations SHOULD require an explicit configuration of which trailers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a trailer `my-custom-key` with value `["attribute_value"]` SHOULD be recorded as the `rpc.response.trailer.my-custom-key` attribute with value `["attribute_value"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to trailers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. The following attributes can be important for making sampling decisions and SHOULD be provided **at span creation time** (if provided at all): * [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) * [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) * [`server.address`](/docs/specs/semconv/registry/attributes/server.md) * [`server.port`](/docs/specs/semconv/registry/attributes/server.md) ### Server **Status:** ![Stable](https://img.shields.io/badge/-stable-lightgreen) This span represents an incoming Remote Procedure Call (RPC). `rpc.system.name` MUST be set to `"grpc"` and SHOULD be provided **at span creation time.** **Span name:** refer to the [Span Name](/docs/specs/semconv/rpc/rpc-spans.md#name) section. **Span kind** MUST be `SERVER`. **Span status**: refer to the [Recording Errors](/docs/specs/semconv/general/recording-errors.md) document for details on how to record span status. See also `rpc.status_code` attribute for the details on which values classify as errors. **Attributes:** | Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values | | --- | --- | --- | --- | --- | --- | | [`rpc.status_code`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The string representation of the [status code](https://github.com/grpc/grpc/blob/v1.75.0/doc/statuscodes.md) returned by the server. [1] | `OK`; `DEADLINE_EXCEEDED`; `UNAVAILABLE` | | [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The Remote Procedure Call (RPC) system. [2] | `grpc` | | [`error.type`](/docs/specs/semconv/registry/attributes/error.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if the operation failed. | string | Describes a class of error the operation ended with. [3] | `UNKNOWN`; `DEADLINE_EXCEEDED`; `UNIMPLEMENTED`; `INTERNAL`; `UNAVAILABLE`; `DATA_LOSS` | | [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` if available. | string | The fully-qualified logical name of the method from the RPC interface perspective. [4] | `com.example.ExampleService/exampleMethod`; `EchoService/Echo`; `_OTHER` | | [`rpc.method_original`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if it's different than `rpc.method`. | string | The original name of the method used by the client. | `com.myservice.EchoService/catchAll`; `com.myservice.EchoService/unknownMethod`; `InvalidMethod` | | [`server.port`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` [5] | int | Server port number. [6] | `50051` | | [`network.peer.address`](/docs/specs/semconv/registry/attributes/network.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` | string | Peer address of the network connection - IP address or UNIX domain socket name. [7] | `10.1.2.80`; `/tmp/my.sock` | | [`network.peer.port`](/docs/specs/semconv/registry/attributes/network.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` If `network.peer.address` is set. | int | Peer port number of the network connection. | `65123` | | [`server.address`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Recommended` when available. | string | A string identifying a group of RPC server instances request is sent to. [8] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | | [`rpc.request.header.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC request headers, also called [request metadata](https://grpc.io/docs/guides/metadata/). [9] | `["1.2.3.4", "1.2.3.5"]` | | [`rpc.response.header.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC response headers, also called [initial metadata](https://grpc.io/docs/what-is-grpc/core-concepts/#rpc-life-cycle). [10] | `["attribute_value"]` | | [`rpc.response.trailer.`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Release Candidate](https://img.shields.io/badge/-rc-mediumorchid) | `Opt-In` | string[] | gRPC response trailers, also called [trailing metadata](https://grpc.io/docs/what-is-grpc/core-concepts/#rpc-life-cycle). [11] | `["attribute_value"]` | **[1] `rpc.status_code`:** The following status codes SHOULD be considered errors: - `UNKNOWN` - `DEADLINE_EXCEEDED` - `UNIMPLEMENTED` - `INTERNAL` - `UNAVAILABLE` - `DATA_LOSS` Instrumentations MAY use additional context or provide configuration options to customize which status codes are considered errors. **[2] `rpc.system.name`:** MUST be set to `grpc`. **[3] `error.type`:** If the RPC fails with an error before status code is returned, `error.type` SHOULD be set to the exception type (its fully-qualified class name, if applicable) or a component-specific, low cardinality error identifier. If a status code is returned and it indicates an error, `error.type` SHOULD be set to that status code. Check system-specific conventions for the details on which values of `rpc.status_code` are considered errors. The `error.type` value SHOULD be predictable and SHOULD have low cardinality. Instrumentations SHOULD document the list of errors they report. If the request has completed successfully, instrumentations SHOULD NOT set `error.type`. **[4] `rpc.method`:** The method name MAY have unbounded cardinality in edge or error cases. Some RPC frameworks or libraries provide a fixed set of recognized methods for client stubs and server implementations. Instrumentations for such frameworks MUST set this attribute to the original method name only when the method is recognized by the framework or library. When the method is not recognized, for example, when the server receives a request for a method that is not predefined on the server, or when instrumentation is not able to reliably detect if the method is predefined, the attribute MUST be set to `_OTHER`. If the RPC instrumentation could end up converting valid RPC methods to `_OTHER`, then it SHOULD provide a way to configure the list of recognized RPC methods. The `rpc.method` can be different from the name of any implementing method/function. The `code.function.name` attribute may be used to record the fully-qualified method actually executing the call on the server side, or the RPC client stub method on the client side. **[5] `server.port`:** If `server.address` is set and the port is present in `:authority`. **[6] `server.port`:** Instrumentations SHOULD populate `server.port` from the port component of the HTTP/2 `:authority` pseudo-header the client used to reach this server. Instrumentations SHOULD NOT use actual network-level connection information for this purpose. **[7] `network.peer.address`:** If a RPC involved multiple network calls (for example retries), the last contacted address SHOULD be used. **[8] `server.address`:** Instrumentations SHOULD populate `server.address` from the host component of the HTTP/2 `:authority` pseudo-header the client used to reach this server. Instrumentations SHOULD NOT use actual network-level connection information for this purpose. **[9] `rpc.request.header.`:** `` is the normalized header name (lowercase), the value is the header values. Instrumentations SHOULD require an explicit configuration of which headers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a header `my-custom-key` with value `["1.2.3.4", "1.2.3.5"]` SHOULD be recorded as the `rpc.request.header.my-custom-key` attribute with value `["1.2.3.4", "1.2.3.5"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to headers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. **[10] `rpc.response.header.`:** `` is the normalized header name (lowercase), the value is the header values. Instrumentations SHOULD require an explicit configuration of which headers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a header `my-custom-key` with value `["attribute_value"]` SHOULD be recorded as the `rpc.response.header.my-custom-key` attribute with value `["attribute_value"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to headers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. **[11] `rpc.response.trailer.`:** `` is the normalized trailer name (lowercase), the value is the trailer values. Instrumentations SHOULD require an explicit configuration of which trailers are to be captured. Capturing all of them can be a security risk - explicit configuration helps avoid leaking sensitive information. For example, a trailer `my-custom-key` with value `["attribute_value"]` SHOULD be recorded as the `rpc.response.trailer.my-custom-key` attribute with value `["attribute_value"]`. The attribute value MUST consist of either multiple values as an array of strings or a single-item array containing a possibly comma-concatenated string, depending on the way the RPC library provides access to trailers. Values under keys ending in [`-bin`](https://github.com/grpc/grpc/blob/v1.75.0/doc/PROTOCOL-HTTP2.md#requests) are binary and SHOULD be base64-encoded when recorded. The following attributes can be important for making sampling decisions and SHOULD be provided **at span creation time** (if provided at all): * [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) * [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) * [`server.address`](/docs/specs/semconv/registry/attributes/server.md) * [`server.port`](/docs/specs/semconv/registry/attributes/server.md) ## Metrics gRPC instrumentations SHOULD collect metrics according to the general [Semantic Conventions for RPC Metrics](/docs/specs/semconv/rpc/rpc-metrics.md). `rpc.system.name` MUST be set to `"grpc"`. The call-duration bucket recommendations below match those used by [gRPC's existing OpenTelemetry metrics](https://github.com/grpc/proposal/blob/master/A66-otel-stats.md#units). ### Metric: `rpc.server.call.duration` (gRPC) This metric is [recommended][MetricRecommended]. This metric follows the common [`rpc.server.call.duration`](/docs/specs/semconv/rpc/rpc-metrics.md#metric-rpcservercallduration) definition. This metric SHOULD be specified with [`ExplicitBucketBoundaries`](/docs/specs/otel/metrics/api/#instrument-advisory-parameters) of `[ 0, 0.00001, 0.00005, 0.0001, 0.0003, 0.0006, 0.0008, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.008, 0.01, 0.013, 0.016, 0.02, 0.025, 0.03, 0.04, 0.05, 0.065, 0.08, 0.1, 0.13, 0.16, 0.2, 0.25, 0.3, 0.4, 0.5, 0.65, 0.8, 1, 2, 5, 10, 20, 50, 100 ]` in seconds, instead of the general RPC bucket boundaries. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `rpc.server.call.duration` | Histogram | `s` | Measures the duration of an incoming gRPC call. [1] | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | | **[1]:** When this metric is reported alongside an RPC server span, the metric value SHOULD be the same as the RPC server span duration. **Attributes:** | Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values | | --- | --- | --- | --- | --- | --- | | [`rpc.status_code`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The string representation of the [status code](https://github.com/grpc/grpc/blob/v1.75.0/doc/statuscodes.md) returned by the server. [1] | `OK`; `DEADLINE_EXCEEDED`; `UNAVAILABLE` | | [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The Remote Procedure Call (RPC) system. [2] | `grpc` | | [`error.type`](/docs/specs/semconv/registry/attributes/error.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if the operation failed. | string | Describes a class of error the operation ended with. [3] | `UNKNOWN`; `DEADLINE_EXCEEDED`; `UNIMPLEMENTED`; `INTERNAL`; `UNAVAILABLE`; `DATA_LOSS` | | [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` if available. | string | The fully-qualified logical name of the method from the RPC interface perspective. [4] | `com.example.ExampleService/exampleMethod`; `EchoService/Echo`; `_OTHER` | | [`server.address`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Opt-In` | string | A string identifying a group of RPC server instances request is sent to. [5] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | | [`server.port`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Opt-In` | int | Server port number. [6] | `50051` | **[1] `rpc.status_code`:** The following status codes SHOULD be considered errors: - `UNKNOWN` - `DEADLINE_EXCEEDED` - `UNIMPLEMENTED` - `INTERNAL` - `UNAVAILABLE` - `DATA_LOSS` Instrumentations MAY use additional context or provide configuration options to customize which status codes are considered errors. **[2] `rpc.system.name`:** MUST be set to `grpc`. **[3] `error.type`:** If the RPC fails with an error before status code is returned, `error.type` SHOULD be set to the exception type (its fully-qualified class name, if applicable) or a component-specific, low cardinality error identifier. If a status code is returned and it indicates an error, `error.type` SHOULD be set to that status code. Check system-specific conventions for the details on which values of `rpc.status_code` are considered errors. The `error.type` value SHOULD be predictable and SHOULD have low cardinality. Instrumentations SHOULD document the list of errors they report. If the request has completed successfully, instrumentations SHOULD NOT set `error.type`. **[4] `rpc.method`:** The method name MAY have unbounded cardinality in edge or error cases. Some RPC frameworks or libraries provide a fixed set of recognized methods for client stubs and server implementations. Instrumentations for such frameworks MUST set this attribute to the original method name only when the method is recognized by the framework or library. When the method is not recognized, for example, when the server receives a request for a method that is not predefined on the server, or when instrumentation is not able to reliably detect if the method is predefined, the attribute MUST be set to `_OTHER`. If the RPC instrumentation could end up converting valid RPC methods to `_OTHER`, then it SHOULD provide a way to configure the list of recognized RPC methods. The `rpc.method` can be different from the name of any implementing method/function. The `code.function.name` attribute may be used to record the fully-qualified method actually executing the call on the server side, or the RPC client stub method on the client side. **[5] `server.address`:** Instrumentations SHOULD populate `server.address` from the host component of the HTTP/2 `:authority` pseudo-header the client used to reach this server. Instrumentations SHOULD NOT use actual network-level connection information for this purpose. **[6] `server.port`:** Instrumentations SHOULD populate `server.port` from the port component of the HTTP/2 `:authority` pseudo-header the client used to reach this server. Instrumentations SHOULD NOT use actual network-level connection information for this purpose. ### Metric: `rpc.client.call.duration` (gRPC) This metric is [recommended][MetricRecommended]. This metric follows the common [`rpc.client.call.duration`](/docs/specs/semconv/rpc/rpc-metrics.md#metric-rpcclientcallduration) definition. This metric SHOULD be specified with [`ExplicitBucketBoundaries`](/docs/specs/otel/metrics/api/#instrument-advisory-parameters) of `[ 0, 0.00001, 0.00005, 0.0001, 0.0003, 0.0006, 0.0008, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.008, 0.01, 0.013, 0.016, 0.02, 0.025, 0.03, 0.04, 0.05, 0.065, 0.08, 0.1, 0.13, 0.16, 0.2, 0.25, 0.3, 0.4, 0.5, 0.65, 0.8, 1, 2, 5, 10, 20, 50, 100 ]` in seconds, instead of the general RPC bucket boundaries. | Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations | | -------- | --------------- | ----------- | -------------- | --------- | ------ | | `rpc.client.call.duration` | Histogram | `s` | Measures the duration of an outgoing gRPC call. [1] | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | | **[1]:** When this metric is reported alongside an RPC client span, the metric value SHOULD be the same as the RPC client span duration. **Attributes:** | Key | Stability | [Requirement Level](/docs/specs/semconv/general/attribute-requirement-level/) | Value Type | Description | Example Values | | --- | --- | --- | --- | --- | --- | | [`rpc.method`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The fully-qualified logical name of the method from the RPC interface perspective. [1] | `com.example.ExampleService/exampleMethod`; `EchoService/Echo`; `_OTHER` | | [`rpc.status_code`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The string representation of the [status code](https://github.com/grpc/grpc/blob/v1.75.0/doc/statuscodes.md) returned by the server or generated by the client. [2] | `OK`; `DEADLINE_EXCEEDED`; `UNAVAILABLE` | | [`rpc.system.name`](/docs/specs/semconv/registry/attributes/rpc.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | The Remote Procedure Call (RPC) system. [3] | `grpc` | | [`server.address`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Required` | string | A string identifying a group of RPC server instances request is sent to. [4] | `example.com`; `10.1.2.80`; `/tmp/my.sock` | | [`error.type`](/docs/specs/semconv/registry/attributes/error.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` If and only if the operation failed. | string | Describes a class of error the operation ended with. [5] | `UNKNOWN`; `DEADLINE_EXCEEDED`; `UNIMPLEMENTED`; `INTERNAL`; `UNAVAILABLE`; `DATA_LOSS` | | [`server.port`](/docs/specs/semconv/registry/attributes/server.md) | ![Stable](https://img.shields.io/badge/-stable-lightgreen) | `Conditionally Required` [6] | int | Server port number. [7] | `50051` | **[1] `rpc.method`:** The method name MAY have unbounded cardinality in edge or error cases. Some RPC frameworks or libraries provide a fixed set of recognized methods for client stubs and server implementations. Instrumentations for such frameworks MUST set this attribute to the original method name only when the method is recognized by the framework or library. When the method is not recognized, for example, when the server receives a request for a method that is not predefined on the server, or when instrumentation is not able to reliably detect if the method is predefined, the attribute MUST be set to `_OTHER`. If the RPC instrumentation could end up converting valid RPC methods to `_OTHER`, then it SHOULD provide a way to configure the list of recognized RPC methods. The `rpc.method` can be different from the name of any implementing method/function. The `code.function.name` attribute may be used to record the fully-qualified method actually executing the call on the server side, or the RPC client stub method on the client side. **[2] `rpc.status_code`:** All status codes except `OK` SHOULD be considered errors. Instrumentations MAY use additional context or provide configuration options to customize which status codes are considered errors. **[3] `rpc.system.name`:** MUST be set to `grpc`. **[4] `server.address`:** Instrumentations SHOULD populate `server.address` (along with `server.port`) based on the configuration used when creating the gRPC channel and SHOULD NOT use actual network-level connection information for this purpose to ensure low cardinality. Instrumentations MAY parse address and port from the gRPC target string according to the [gRPC Name Resolution specification](https://grpc.github.io/grpc/core/md_doc_naming.html), depending on the scheme used. Or, they MAY use gRPC client APIs that provide this information. If the instrumentation cannot determine a server domain name or another suitable low-cardinality identifier for a group of server instances from the target string, it SHOULD set `server.address` to the entire target string and SHOULD NOT set `server.port`. When the address is an IP address, instrumentations SHOULD NOT do a reverse DNS lookup to obtain a DNS name and SHOULD set `server.address` to the IP address provided. Examples: - Given the target string `grpc.io:50051`, expected attributes: - `server.address`: `"grpc.io"` - `server.port`: `50051` - Given the target string `dns://1.2.3.4/grpc.io:50051`, expected attributes: - `server.address`: `"grpc.io"` - `server.port`: `50051` - Given the target string `unix:///run/containerd/containerd.sock`, expected attributes: - `server.address`: `"/run/containerd/containerd.sock"` - `server.port`: not set - Given the target string `zk://zookeeper:2181/my-server`, expected attributes: - `server.address`: `"zk://zookeeper:2181/my-server"` - `server.port`: not set - Given the target string `ipv4:198.51.100.123:50051,198.51.100.124:50051`, expected attributes: - `server.address`: `"ipv4:198.51.100.123:50051,198.51.100.124:50051"` - `server.port`: not set **[5] `error.type`:** If the RPC fails with an error before status code is returned, `error.type` SHOULD be set to the exception type (its fully-qualified class name, if applicable) or a component-specific, low cardinality error identifier. If a status code is returned and it indicates an error, `error.type` SHOULD be set to that status code. Check system-specific conventions for the details on which values of `rpc.status_code` are considered errors. The `error.type` value SHOULD be predictable and SHOULD have low cardinality. Instrumentations SHOULD document the list of errors they report. If the request has completed successfully, instrumentations SHOULD NOT set `error.type`. **[6] `server.port`:** If and only if the port is available and `server.address` is set. **[7] `server.port`:** See the `server.address` for details on parsing the target string. [MetricRecommended]: /docs/specs/semconv/general/signal-requirement-level.md#recommended [DocumentStatus]: /docs/specs/otel/document-status/