[ASCII-2053] Add new e2e test for agent hostname on Azure (#29585)

.gitlab/e2e/e2e.yml

@@ -139,7 +139,7 @@ new-e2e-agent-subcommands:
       - EXTRA_PARAMS: --run "Test(Linux|Windows)StatusSuite"
       - EXTRA_PARAMS: --run "Test(Linux|Windows)HealthSuite"
       - EXTRA_PARAMS: --run "Test(Linux|Windows)ConfigSuite"
-      - EXTRA_PARAMS: --run "Test(Linux|Windows)HostnameSuite"
+      - EXTRA_PARAMS: --run "Test(Linux|Windows|LinuxAzure)HostnameSuite"
       - EXTRA_PARAMS: --run "Test(Linux|Windows)DiagnoseSuite"
       - EXTRA_PARAMS: --run "Test(Linux|Windows)ConfigCheckSuite"
       - EXTRA_PARAMS: --run "Test(Linux|Windows)FlareSuite"

test/new-e2e/tests/agent-subcommands/hostname/hostname_azure_nix_test.go

@@ -0,0 +1,84 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-present Datadog, Inc.
+
+package hostname
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/DataDog/test-infra-definitions/components/datadog/agentparams"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/DataDog/datadog-agent/test/new-e2e/pkg/e2e"
+	"github.com/DataDog/datadog-agent/test/new-e2e/pkg/environments"
+	azurehost "github.com/DataDog/datadog-agent/test/new-e2e/pkg/environments/azure/host/linux"
+)
+
+type linuxAzureHostnameSuite struct {
+	e2e.BaseSuite[environments.Host]
+}
+
+func TestLinuxAzureHostnameSuite(t *testing.T) {
+	t.Parallel()
+	e2e.Run(t, &linuxAzureHostnameSuite{}, e2e.WithProvisioner(azurehost.ProvisionerNoFakeIntake()))
+}
+
+func (v *linuxAzureHostnameSuite) TestAgentConfigHostnameFileOverride() {
+	fileContent := "hostname.from.file"
+	v.UpdateEnv(azurehost.ProvisionerNoFakeIntake(azurehost.WithAgentOptions(agentparams.WithFile("/tmp/var/hostname", fileContent, false), agentparams.WithAgentConfig("hostname_file: /tmp/var/hostname"))))
+
+	hostname := v.Env().Agent.Client.Hostname()
+	assert.Equal(v.T(), fileContent, hostname)
+}
+
+// https://github.com/DataDog/datadog-agent/blob/main/pkg/util/hostname/README.md#the-current-logic
+// azure specific logic from pkg/util/cloudproviders/azure/azure.go
+func (v *linuxAzureHostnameSuite) TestAgentHostnameStyle() {
+	hostname := v.Env().RemoteHost.MustExecute("hostname")
+	hostname = strings.TrimSpace(hostname)
+
+	metadataStr := v.Env().RemoteHost.MustExecute(`curl -s -H "Metadata: true" http://169.254.169.254/metadata/instance/compute?api-version=2021-02-01`)
+
+	var metadata struct {
+		VMID              string
+		Name              string
+		ResourceGroupName string
+		SubscriptionID    string
+		OsProfile         struct {
+			ComputerName string
+		}
+	}
+
+	err := json.Unmarshal([]byte(metadataStr), &metadata)
+	require.NoError(v.T(), err)
+
+	hostnameStyles := map[string]interface{}{
+		"":                        hostname,
+		"os":                      hostname,
+		"vmid":                    metadata.VMID,
+		"name":                    metadata.Name,
+		"name_and_resource_group": fmt.Sprintf("%s.%s", metadata.Name, metadata.ResourceGroupName),
+		"full":                    fmt.Sprintf("%s.%s.%s", metadata.Name, metadata.ResourceGroupName, metadata.SubscriptionID),
+		"os_computer_name":        strings.ToLower(metadata.OsProfile.ComputerName),
+	}
+
+	for hostnameStyle, expected := range hostnameStyles {
+		v.Run("hostname_style_"+hostnameStyle, func() {
+			agentConfig := ""
+			if hostnameStyle != "" {
+				agentConfig = "azure_hostname_style: " + hostnameStyle
+			}
+
+			v.UpdateEnv(azurehost.ProvisionerNoFakeIntake(azurehost.WithAgentOptions(agentparams.WithAgentConfig(agentConfig))))
+
+			hostname := v.Env().Agent.Client.Hostname()
+			v.Equal(expected, hostname)
+		})
+	}
+}