Service semantic conventions

Service is a logical component of an application that produces telemetry data (events, metrics, spans, etc.).

In modern, distributed, application architectures:

• A service.namespace is an entire system of components designed for end-users or other applications to leverage.
• A service is one of the logical, distinct components that make up the application, e.g. running as a bundle of the instances that run the same container image for load balancing.
• A service.instance is a distinct instance of a service component, e.g. a specific kubernetes container that is part of a kubernetes deployment which offers a service.

For example, suppose we have a Blog site that consists of a database and an HTTP server which uses the database:

flowchart LR
    App(("`**service.namespace**
           blog-site`"))
    Db["`**service.name**
         db`"]
    Http["`**service.name**
          http-server`"]
    Http1["`**service.instance.id**
            http-server-1231`"]
    Http2["`**service.instance.id**
           http-server-1234`"]
    Db1["`**service.instance.id**
         db-gbgfx`"]
    Db --> Db1
    Http --> Http1
    Http --> Http2
    App --> Db
    App --> Http

Here, we can see the HTTP server has two instances that may use a load-balancer between them. Additionally, there’s a single database instance.

Service

Status:

type: service

Description: A logical unit of an application or system that performs a specific function.

Attributes:

Role	Key	Stability	Requirement Level	Value Type	Description	Example Values
Identity	service.name		Required	string	Logical name of the service. [1]	shoppingcart
Description	service.version		Recommended	string	The version string of the service component. The format is not defined by these conventions.	2.0.0; a01dbef8a

[1] service.name: MUST be the same for all instances of horizontally scaled services. If the value was not specified, SDKs MUST fallback to unknown_service: concatenated with process.executable.name, e.g. unknown_service:bash. If process.executable.name is not available, the value MUST be set to unknown_service.

Service Instance

Status:

type: service.instance

Description: A unique instance of a logical service.

Attributes:

Role	Key	Stability	Requirement Level	Value Type	Description	Example Values
Identity	service.instance.id		Required	string	The string ID of the service instance. [1]	627cc493-f310-47de-96bd-71410b7dec09

[1] service.instance.id: MUST be unique for each instance of the same service.namespace,service.name pair (in other words service.namespace,service.name,service.instance.id triplet MUST be globally unique). The ID helps to distinguish instances of the same service that exist at the same time (e.g. instances of a horizontally scaled service).

Implementations, such as SDKs, are recommended to generate a random Version 1 or Version 4 RFC 4122 UUID, but are free to use an inherent unique ID as the source of this value if stability is desirable. In that case, the ID SHOULD be used as source of a UUID Version 5 and SHOULD use the following UUID as the namespace: 4d63009a-8d0f-11ee-aad7-4c796ed8e320.

UUIDs are typically recommended, as only an opaque value for the purposes of identifying a service instance is needed. Similar to what can be seen in the man page for the /etc/machine-id file, the underlying data, such as pod name and namespace should be treated as confidential, being the user’s choice to expose it or not via another resource attribute.

For applications running behind an application server (like unicorn), we do not recommend using one identifier for all processes participating in the application. Instead, it’s recommended each division (e.g. a worker thread in unicorn) to have its own instance.id.

It’s not recommended for a Collector to set service.instance.id if it can’t unambiguously determine the service instance that is generating that telemetry. For instance, creating an UUID based on pod.name will likely be wrong, as the Collector might not know from which container within that pod the telemetry originated. However, Collectors can set the service.instance.id if they can unambiguously determine the service instance for that telemetry. This is typically the case for scraping receivers, as they know the target address and port.

Service Namespace

Status:

type: service.namespace

Description: Groups related services that compose a system or application under a common namespace.

Attributes:

Role	Key	Stability	Requirement Level	Value Type	Description	Example Values
Identity	service.namespace		Required	string	A namespace for service.name. [1]	Shop

[1] service.namespace: A string value having a meaning that helps to distinguish a group of services, for example the team name that owns a group of services. service.name is expected to be unique within the same namespace. If service.namespace is not specified in the Resource then service.name is expected to be unique for all services that have no explicit namespace defined (so the empty/unspecified namespace is simply one more valid namespace). Zero-length namespace string is assumed equal to unspecified namespace.