From 2ded8f25ecf7c435ea12006d69303084f3adbe5c Mon Sep 17 00:00:00 2001
From: Paul Meyer <paulmey@microsoft.com>
Date: Wed, 25 Sep 2019 21:13:09 +0000
Subject: [PATCH] Add metadata client

---
 builder/azure/common/client/metadata.go      | 81 ++++++++++++++++++++
 builder/azure/common/client/metadata_test.go | 33 ++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 builder/azure/common/client/metadata.go
 create mode 100644 builder/azure/common/client/metadata_test.go

diff --git a/builder/azure/common/client/metadata.go b/builder/azure/common/client/metadata.go
new file mode 100644
index 000000000..ad76cb007
--- /dev/null
+++ b/builder/azure/common/client/metadata.go
@@ -0,0 +1,81 @@
+package client
+
+import (
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/Azure/go-autorest/autorest"
+	"github.com/Azure/go-autorest/autorest/azure"
+)
+
+// DefaultMetadataClient is the default instance metadata client for Azure. Replace this variable for testing purposes only
+var DefaultMetadataClient = NewMetadataClient()
+
+// MetadataClient holds methods that Packer uses to get information about the current VM
+type MetadataClientAPI interface {
+	GetComputeInfo() (*ComputeInfo, error)
+}
+
+type ComputeInfo struct{
+	Name              string
+	ResourceGroupName string
+	SubscriptionID    string
+Location string
+}
+
+// metadataClient implements MetadataClient
+type metadataClient struct {
+	autorest.Sender
+}
+
+var _ MetadataClientAPI = metadataClient{}
+
+const imdsURL = "http://169.254.169.254/metadata/instance?api-version=2017-08-01"
+
+// VMResourceID returns the resource ID of the current VM
+func (client metadataClient) GetComputeInfo() (*ComputeInfo, error) {
+	req, err := autorest.CreatePreparer(
+		autorest.AsGet(),
+		autorest.WithHeader("Metadata", "true"),
+		autorest.WithBaseURL(imdsURL),
+	).Prepare((&http.Request{}))
+	if err != nil {
+		return nil, err
+	}
+
+	res, err := autorest.SendWithSender(client, req,
+		autorest.DoRetryForDuration(1*time.Minute, 5*time.Second))
+	if err != nil {
+		return nil, err
+	}
+
+	var vminfo struct {
+		ComputeInfo `json:"compute"`
+	}
+
+	err = autorest.Respond(
+		res,
+		azure.WithErrorUnlessStatusCode(http.StatusOK),
+		autorest.ByUnmarshallingJSON(&vminfo),
+		autorest.ByClosing())
+	if err != nil {
+		return nil, err
+	}
+	return &vminfo.ComputeInfo, nil
+}
+
+func(ci ComputeInfo) ResourceID() string{
+	return fmt.Sprintf("/subscriptions/%s/resourceGroups/%s/providers/Microsoft.Compute/virtualMachines/%s",
+		ci.SubscriptionID,
+		ci.ResourceGroupName,
+		ci.Name,
+	)
+}
+
+// NewMetadataClient creates a new instance metadata client
+func NewMetadataClient() MetadataClientAPI {
+	return metadataClient{
+		Sender: autorest.CreateSender(),
+	}
+}
diff --git a/builder/azure/common/client/metadata_test.go b/builder/azure/common/client/metadata_test.go
new file mode 100644
index 000000000..dddc9a2a0
--- /dev/null
+++ b/builder/azure/common/client/metadata_test.go
@@ -0,0 +1,33 @@
+package client
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/Azure/go-autorest/autorest/azure"
+
+	"github.com/hashicorp/packer/builder/azure/common"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_MetadataReturnsComputeInfo(t *testing.T) {
+	if !common.IsAzure() {
+		t.Skipf("Not running on Azure, skipping live IMDS test")
+	}
+	mdc := NewMetadataClient()
+	info, err := mdc.GetComputeInfo()
+	assert.Nil(t, err)
+
+	vm, err := azure.ParseResourceID(fmt.Sprintf(
+		"/subscriptions/%s"+
+			"/resourceGroups/%s"+
+			"/providers/Microsoft.Compute"+
+			"/virtualMachines/%s",
+		info.SubscriptionID,
+		info.ResourceGroupName,
+		info.Name))
+	assert.Nil(t, err, "%q is not parsable as an Azure resource info", info)
+
+	assert.Regexp(t, "^[0-9a-fA-F-]{36}$", vm.SubscriptionID)
+	t.Logf("VM: %+v", vm)
+}