# Host **Status**: [Experimental][DocumentStatus] **type:** `host` **Description:** A host is defined as a computing instance. For example, physical servers, virtual machines, switches or disk array. The `host.*` namespace SHOULD be exclusively used to capture resource attributes. To report host metrics, the `system.*` namespace SHOULD be used. | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`host.arch`](/docs/attributes-registry/host.md) | string | The CPU architecture the host system is running on. | `amd64`; `arm32`; `arm64` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.id`](/docs/attributes-registry/host.md) | string | Unique host ID. For Cloud, this must be the instance_id assigned by the cloud provider. For non-containerized systems, this should be the `machine-id`. See the table below for the sources to use to determine the `machine-id` based on operating system. [1] | `fdbf79e8af94cb7f9e8df36789187052` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.image.id`](/docs/attributes-registry/host.md) | string | VM image ID or host OS image ID. For Cloud, this value is from the provider. | `ami-07b06b442921831e5` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.image.name`](/docs/attributes-registry/host.md) | string | Name of the VM image or OS install the host was instantiated from. | `infra-ami-eks-worker-node-7d4ec78312`; `CentOS-8-x86_64-1905` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.image.version`](/docs/attributes-registry/host.md) | string | The version string of the VM image or host OS as defined in [Version Attributes](/docs/resource/README.md#version-attributes). | `0.1` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.name`](/docs/attributes-registry/host.md) | string | Name of the host. On Unix systems, it may contain what the hostname command returns, or the fully qualified hostname, or another name specified by the user. | `opentelemetry-test` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.type`](/docs/attributes-registry/host.md) | string | Type of host. For Cloud, this must be the machine type. | `n1-standard-1` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.ip`](/docs/attributes-registry/host.md) | string[] | Available IP addresses of the host, excluding loopback interfaces. [2] | `["192.168.1.140", "fe80::abc2:4a28:737a:609e"]` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.mac`](/docs/attributes-registry/host.md) | string[] | Available MAC addresses of the host, excluding loopback interfaces. [3] | `["AC-DE-48-23-45-67", "AC-DE-48-23-45-67-01-9F"]` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | **[1]:** Collecting `host.id` from non-containerized systems **Non-privileged Machine ID Lookup** When collecting `host.id` for non-containerized systems non-privileged lookups of the machine id are preferred. SDK detector implementations MUST use the sources listed below to obtain the machine id. | OS | Primary | Fallback | |---------|---------|---------| | Linux | contents of `/etc/machine-id` | contents of `/var/lib/dbus/machine-id` | | BSD | contents of `/etc/hostid` | output of `kenv -q smbios.system.uuid` | | MacOS | `IOPlatformUUID` line from the output of `ioreg -rd1 -c "IOPlatformExpertDevice"` | - | | Windows | `MachineGuid` from registry `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography` | - | **Privileged Machine ID Lookup** The `host.id` can be looked up using privileged sources. For example, Linux systems can use the output of `dmidecode -t system`, `dmidecode -t baseboard`, `dmidecode -t chassis`, or read the corresponding data from the filesystem (e.g. `cat /sys/devices/virtual/dmi/id/product_id`, `cat /sys/devices/virtual/dmi/id/product_uuid`, etc), however, SDK resource detector implementations MUST not collect `host.id` from privileged sources. If privileged lookup of `host.id` is required, the value should be injected via the `OTEL_RESOURCE_ATTRIBUTES` environment variable. **[2]:** IPv4 Addresses MUST be specified in dotted-quad notation. IPv6 addresses MUST be specified in the [RFC 5952](https://www.rfc-editor.org/rfc/rfc5952.html) format. **[3]:** MAC Addresses MUST be represented in [IEEE RA hexadecimal form](https://standards.ieee.org/wp-content/uploads/import/documents/tutorials/eui.pdf): as hyphen-separated octets in uppercase hexadecimal form from most to least significant. `host.arch` 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 | Stability | |---|---|---| | `amd64` | AMD64 | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `arm32` | ARM32 | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `arm64` | ARM64 | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `ia64` | Itanium | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `ppc32` | 32-bit PowerPC | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `ppc64` | 64-bit PowerPC | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `s390x` | IBM z/Architecture | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | `x86` | 32-bit x86 | ![Experimental](https://img.shields.io/badge/-experimental-blue) | **type:** `host.cpu` | Attribute | Type | Description | Examples | [Requirement Level](https://opentelemetry.io/docs/specs/semconv/general/attribute-requirement-level/) | Stability | |---|---|---|---|---|---| | [`host.cpu.cache.l2.size`](/docs/attributes-registry/host.md) | int | The amount of level 2 memory cache available to the processor (in Bytes). | `12288000` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.cpu.family`](/docs/attributes-registry/host.md) | string | Family or generation of the CPU. | `6`; `PA-RISC 1.1e` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.cpu.model.id`](/docs/attributes-registry/host.md) | string | Model identifier. It provides more granular information about the CPU, distinguishing it from other CPUs within the same family. | `6`; `9000/778/B180L` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.cpu.model.name`](/docs/attributes-registry/host.md) | string | Model designation of the processor. | `11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.cpu.stepping`](/docs/attributes-registry/host.md) | string | Stepping or core revisions. | `1`; `r1p1` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | | [`host.cpu.vendor.id`](/docs/attributes-registry/host.md) | string | Processor manufacturer identifier. A maximum 12-character string. [1] | `GenuineIntel` | `Opt-In` | ![Experimental](https://img.shields.io/badge/-experimental-blue) | **[1]:** [CPUID](https://wiki.osdev.org/CPUID) command returns the vendor ID string in EBX, EDX and ECX registers. Writing these to memory in this order results in a 12-character string. [DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status