[receiver/azuremonitorreceiver] feat: add subscription name resource attribute (#39029)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
The subscription name is often more speaking for people playing with
metrics, than the subscription id which is an uuid.
Hence this PR. 

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Linked with #38895. I prefer to have a separate PR for the add of
subscription name in resource attributes to have one PR by feature.

<!--Describe what testing was performed and which tests were added.-->
#### Testing
Added unit tests + new mock API to mock the new get by subscription
calls.

<!--Describe the documentation added.-->
#### Documentation

<!--Please delete paragraphs that you did not use before submitting.-->

Signed-off-by: Célian Garcia <[email protected]>
Co-authored-by: Antoine Toulme <[email protected]>

Author: celian-garcia

.chloggen/azuremonitorreceiver_add-subscription-name.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: azuremonitorreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add subscription name resource attribute
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39029]
+
+# (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:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/azuremonitorreceiver/README.md

@@ -145,3 +145,53 @@ receivers:
 ## Metrics
 
 Details about the metrics scraped by this receiver can be found in [Supported metrics with Azure Monitor](https://learn.microsoft.com/en-us/azure/azure-monitor/essentials/metrics-supported). This receiver adds the prefix "azure_" to all scraped metrics.
+
+## Azure API calls summary
+At each collection interval, here are the different Azure API that can be called.
+It can be useful to know that, in order to configure the client permission in Azure or to choose the 
+right configuration based on your needs.
+
+### [Subscriptions - Get](https://learn.microsoft.com/en-us/rest/api/resources/subscriptions/get?view=rest-resources-2022-12-01&tabs=HTTP)
+```yaml
+conditions:
+- subscription_ids is set
+- discover_subscriptions is false or not set
+- resource_attributes.subscription.enabled is true
+cardinality: once per sub id
+```
+### [Subscriptions - List](https://learn.microsoft.com/en-us/rest/api/resources/subscriptions/list?view=rest-resources-2022-12-01&tabs=HTTP)
+```yaml
+conditions:
+- discover_subscriptions is true
+cardinality: once per *page of sub
+```
+
+### [Resources - List](https://learn.microsoft.com/en-us/rest/api/resources/resources/list?view=rest-resources-2022-12-01&tabs=HTTP)
+```yaml
+conditions:
+- always
+cardinality: once per sub id
+```
+
+### [Metrics Definitions - List](https://learn.microsoft.com/en-us/rest/api/monitor/metric-definitions/list?view=rest-monitor-2023-10-01&tabs=HTTP)
+```yaml
+conditions: always
+cardinality: once per res id and *page of metrics def
+```
+
+### [Metrics - List](https://learn.microsoft.com/en-us/rest/api/monitor/metrics/list?view=rest-monitor-2023-10-01&tabs=HTTP)
+```yaml
+conditions: always
+cardinality: once per res id, *page of metrics, and **composite key
+```
+> *page size has not been clearly identified, reading the documentation. Even Chat Bots lose themselves
+> with the "top"/"$top" filter that doesn't seem related, and give random results from 10 to 1000...
+> 
+> **the composite key is an identifier formed with info retrieved in metric definitions.
+Useful to group and reduce the number of metrics calls.
+It is composed by 
+> - dimensions,
+> - aggregations, 
+> - minimum timegrain.
+> 
+> It is used to get several metrics in one request.

receiver/azuremonitorreceiver/documentation.md

@@ -6,5 +6,6 @@
 
 | Name | Description | Values | Enabled |
 | ---- | ----------- | ------ | ------- |
+| azuremonitor.subscription | Azure subscription name | Any Str | false |
 | azuremonitor.subscription_id | Azure subscription ID | Any Str | false |
 | azuremonitor.tenant_id | Azure tenant ID | Any Str | false |

receiver/azuremonitorreceiver/internal/metadata/generated_config.go

@@ -1,12 +1,16 @@
 default:
 all_set:
   resource_attributes:
+    azuremonitor.subscription:
+      enabled: true
     azuremonitor.subscription_id:
       enabled: true
     azuremonitor.tenant_id:
       enabled: true
 none_set:
   resource_attributes:
+    azuremonitor.subscription:
+      enabled: false
     azuremonitor.subscription_id:
       enabled: false
     azuremonitor.tenant_id:

receiver/azuremonitorreceiver/internal/metadata/generated_config_test.go

@@ -15,6 +15,9 @@ resource_attributes:
   azuremonitor.subscription_id:
     description: Azure subscription ID
     type: string
+  azuremonitor.subscription:
+    description: Azure subscription name
+    type: string
 
 tests:
   config:

receiver/azuremonitorreceiver/internal/metadata/generated_resource.go

@@ -87,12 +87,14 @@ type mockClientOptionsResolver struct {
 // Indeed, the way to mock Azure API is to provide a fake server that will return the expected data.
 // The fake server is built with "fake" package from Azure SDK for Go, and is set in the client options, via the transport.
 // This ctor takes the mock data in that order:
-// - subscriptions
+// - subscriptions get responses stored by ID
+// - subscriptions list response
 // - resources stored by subscription ID
 // - metrics definitions stored by resource URI
 // - metrics values stored by resource URI and metric name
 func newMockClientOptionsResolver(
-	subscriptions []armsubscriptions.ClientListResponse,
+	subscriptionsGetResponsesByID map[string]armsubscriptions.ClientGetResponse,
+	subscriptionsListResponse []armsubscriptions.ClientListResponse,
 	resources map[string][]armresources.ClientListResponse,
 	metricsDefinitions map[string][]armmonitor.MetricDefinitionsClientListResponse,
 	metrics map[string]map[string]armmonitor.MetricsClientListResponse,
@@ -112,7 +114,8 @@ func newMockClientOptionsResolver(
 
 	// Init subscriptions client options from subscriptions mock data
 	subscriptionsServer := armsubscriptionsfake.Server{
-		NewListPager: newMockSubscriptionsListPager(subscriptions),
+		NewListPager: newMockSubscriptionsListPager(subscriptionsListResponse),
+		Get:          newMockSubscriptionGet(subscriptionsGetResponsesByID),
 	}
 	armSubscriptionsClientOptions := &arm.ClientOptions{
 		ClientOptions: azcore.ClientOptions{