Add fallback for host.id in Cloud

.chloggen/ck_host.id.yaml

@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+#
+# If your change doesn't affect end users you should instead start
+# your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the area of concern in the attributes-registry, (e.g. http, cloud, db)
+component: host
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Add fallback for `host.id` in Cloud"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+# The values here must be integers.
+issues: [576]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

docs/attributes-registry/host.md

@@ -15,7 +15,7 @@
 | `host.cpu.model.name` | string | Model designation of the processor. | `11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `host.cpu.stepping` | string | Stepping or core revisions. | `1`; `r1p1` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `host.cpu.vendor.id` | string | Processor manufacturer identifier. A maximum 12-character string. [1] | `GenuineIntel` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
-| `host.id` | 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. | `fdbf79e8af94cb7f9e8df36789187052` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| `host.id` | string | Unique host ID. For Cloud, this must be the instance_id assigned by the cloud provider. If the instance_id can not be retrieved, or 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. | `fdbf79e8af94cb7f9e8df36789187052` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `host.image.id` | string | VM image ID or host OS image ID. For Cloud, this value is from the provider. | `ami-07b06b442921831e5` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `host.image.name` | 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` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | `host.image.version` | string | The version string of the VM image or host OS as defined in [Version Attributes](/docs/resource/README.md#version-attributes). | `0.1` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |

docs/resource/host.md

@@ -13,7 +13,7 @@ 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`](../attributes-registry/host.md) | string | The CPU architecture the host system is running on. | `amd64` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
-| [`host.id`](../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. | `fdbf79e8af94cb7f9e8df36789187052` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
+| [`host.id`](../attributes-registry/host.md) | string | Unique host ID. For Cloud, this must be the instance_id assigned by the cloud provider. If the instance_id can not be retrieved, or 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. | `fdbf79e8af94cb7f9e8df36789187052` | `Recommended` | ![Experimental](https://img.shields.io/badge/-experimental-blue) |
 | [`host.image.id`](../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`](../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`](../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) |

model/registry/host.yaml

@@ -10,8 +10,9 @@ groups:
         stability: experimental
         brief: >
           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.
+          If the instance_id can not be retrieved, or 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.
         examples: ['fdbf79e8af94cb7f9e8df36789187052']
       - id: name
         type: string