[internal/metadataproviders/azure] Fix memory leak on AKS (#32574)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
From [`client.Do` documentation](https://pkg.go.dev/net/http#Client.Do),
a client's response can safely be ignored when an error is returned, but
must be handled in all other cases, even when a response code is not
2XX. This fixes the internal AKS detection to properly close the
response body in the case of a non-200 status returned.

This also enables `goleak` on the `internal/metadata/azure` package
which helps ensure no goroutines are being leaked. `goleak` is what
detected this bug.

**Link to tracking Issue:** <Issue number if applicable>
#30438

**Testing:** <Describe what testing was performed and which tests were
added.>
All existing tests are passing as well as added `goleak` check.

.chloggen/goleak_internalazure.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: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: processor/resourcedetection, exporter/datadog
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix memory leak on AKS
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32574]
+
+# (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: []

internal/metadataproviders/azure/metadata.go

@@ -74,12 +74,13 @@ func (p *azureProviderImpl) Metadata(ctx context.Context) (*ComputeMetadata, err
 	resp, err := p.client.Do(req)
 	if err != nil {
 		return nil, fmt.Errorf("failed to query Azure IMDS: %w", err)
-	} else if resp.StatusCode != 200 {
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
 		//lint:ignore ST1005 Azure is a capitalized proper noun here
 		return nil, fmt.Errorf("Azure IMDS replied with status code: %s", resp.Status)
 	}
 
-	defer resp.Body.Close()
 	respBody, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read Azure IMDS reply: %w", err)

internal/metadataproviders/azure/package_test.go

@@ -0,0 +1,14 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package azure
+
+import (
+	"testing"
+
+	"go.uber.org/goleak"
+)
+
+func TestMain(m *testing.M) {
+	goleak.VerifyTestMain(m)
+}