Change Azure billing API from GET to POST method (#3334)

Signed-off-by: Saurav Teli <telisaurav44@gmail.com>

pkg/cloud/azure/pricesheetclient.go

@@ -111,7 +111,7 @@ func (client *PriceSheetClient) downloadByBillingPeriodCreateRequest(ctx context
 		return nil, errors.New("parameter billingPeriodName cannot be empty")
 	}
 	urlPath := fmt.Sprintf(downloadByBillingPeriodTemplate, url.PathEscape(client.billingAccountID), url.PathEscape(billingPeriodName))
-	req, err := runtime.NewRequest(ctx, http.MethodGet, runtime.JoinPaths(client.host, urlPath))
+	req, err := runtime.NewRequest(ctx, http.MethodPost, runtime.JoinPaths(client.host, urlPath))
 	if err != nil {
 		return nil, err
 	}

pkg/cloud/azure/pricesheetclient_test.go

@@ -0,0 +1,181 @@
+package azure
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore"
+	"github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// mockCredential implements azcore.TokenCredential for testing
+type mockCredential struct{}
+
+func (m *mockCredential) GetToken(ctx context.Context, options policy.TokenRequestOptions) (azcore.AccessToken, error) {
+	return azcore.AccessToken{
+		Token:     "mock-token",
+		ExpiresOn: time.Now().Add(time.Hour),
+	}, nil
+}
+
+// TestPriceSheetClient_CreateRequest tests the core HTTP method fix
+// This test directly validates the createRequest method to ensure POST is used
+func TestPriceSheetClient_CreateRequest_HTTPMethod(t *testing.T) {
+	tests := []struct {
+		name              string
+		billingAccountID  string
+		billingPeriodName string
+		expectedMethod    string
+		expectedPath      string
+	}{
+		{
+			name:              "POST method for valid billing account",
+			billingAccountID:  "test-billing-account",
+			billingPeriodName: "202308",
+			expectedMethod:    "POST",
+			expectedPath:      "/providers/Microsoft.Billing/billingAccounts/test-billing-account/billingPeriods/202308/providers/Microsoft.Consumption/pricesheets/download",
+		},
+		{
+			name:              "POST method for different billing period",
+			billingAccountID:  "another-account",
+			billingPeriodName: "202401",
+			expectedMethod:    "POST",
+			expectedPath:      "/providers/Microsoft.Billing/billingAccounts/another-account/billingPeriods/202401/providers/Microsoft.Consumption/pricesheets/download",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cred := &mockCredential{}
+			client, err := NewPriceSheetClient(tt.billingAccountID, cred, nil)
+			require.NoError(t, err)
+
+			// Test the createRequest method directly
+			req, err := client.downloadByBillingPeriodCreateRequest(context.Background(), tt.billingPeriodName)
+			require.NoError(t, err)
+
+			// Validate HTTP method - this is the core fix validation
+			assert.Equal(t, tt.expectedMethod, req.Raw().Method, "HTTP method must be POST, not GET (fix for Azure billing API issue #3326)")
+
+			// Validate URL path construction
+			assert.Contains(t, req.Raw().URL.Path, tt.expectedPath)
+
+			// Validate query parameters
+			assert.Equal(t, "2022-06-01", req.Raw().URL.Query().Get("api-version"))
+			assert.Equal(t, "en", req.Raw().URL.Query().Get("ln"))
+
+			// Validate Accept header
+			assert.Equal(t, []string{"*/*"}, req.Raw().Header["Accept"])
+		})
+	}
+}
+
+// TestPriceSheetClient_Validation tests parameter validation
+func TestPriceSheetClient_Validation(t *testing.T) {
+	cred := &mockCredential{}
+
+	tests := []struct {
+		name              string
+		billingAccountID  string
+		billingPeriodName string
+		expectError       bool
+		expectedError     string
+	}{
+		{
+			name:              "empty billing account ID",
+			billingAccountID:  "",
+			billingPeriodName: "202308",
+			expectError:       true,
+			expectedError:     "parameter client.billingAccountID cannot be empty",
+		},
+		{
+			name:              "empty billing period name",
+			billingAccountID:  "test-account",
+			billingPeriodName: "",
+			expectError:       true,
+			expectedError:     "parameter billingPeriodName cannot be empty",
+		},
+		{
+			name:              "valid parameters",
+			billingAccountID:  "test-account",
+			billingPeriodName: "202308",
+			expectError:       false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			client, err := NewPriceSheetClient(tt.billingAccountID, cred, nil)
+			require.NoError(t, err)
+
+			// Test the createRequest method directly for validation
+			_, err = client.downloadByBillingPeriodCreateRequest(context.Background(), tt.billingPeriodName)
+
+			if tt.expectError {
+				assert.Error(t, err)
+				assert.Contains(t, err.Error(), tt.expectedError)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+// TestPriceSheetClient_URLConstruction tests URL path construction
+func TestPriceSheetClient_URLConstruction(t *testing.T) {
+	tests := []struct {
+		name              string
+		billingAccountID  string
+		billingPeriodName string
+		expectedPath      string
+	}{
+		{
+			name:              "standard billing account and period",
+			billingAccountID:  "123456789",
+			billingPeriodName: "202308",
+			expectedPath:      "/providers/Microsoft.Billing/billingAccounts/123456789/billingPeriods/202308/providers/Microsoft.Consumption/pricesheets/download",
+		},
+		{
+			name:              "billing account with dashes",
+			billingAccountID:  "account-with-dashes",
+			billingPeriodName: "202308",
+			expectedPath:      "/providers/Microsoft.Billing/billingAccounts/account-with-dashes/billingPeriods/202308/providers/Microsoft.Consumption/pricesheets/download",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cred := &mockCredential{}
+			client, err := NewPriceSheetClient(tt.billingAccountID, cred, nil)
+			require.NoError(t, err)
+
+			req, err := client.downloadByBillingPeriodCreateRequest(context.Background(), tt.billingPeriodName)
+			require.NoError(t, err)
+
+			// Verify URL path construction
+			assert.Contains(t, req.Raw().URL.Path, tt.expectedPath)
+		})
+	}
+}
+
+// TestPriceSheetClient_MethodRegression ensures the HTTP method fix doesn't regress
+// This test would fail if someone accidentally changed POST back to GET
+func TestPriceSheetClient_MethodRegression(t *testing.T) {
+	// This test specifically prevents regression of issue #3326
+	// where Azure billing API was incorrectly using GET instead of POST
+	cred := &mockCredential{}
+	client, err := NewPriceSheetClient("test-billing-account", cred, nil)
+	require.NoError(t, err)
+
+	req, err := client.downloadByBillingPeriodCreateRequest(context.Background(), "202308")
+	require.NoError(t, err)
+
+	// Critical assertion: must be POST, never GET
+	// This is the core fix for Azure billing account pricing API
+	assert.Equal(t, "POST", req.Raw().Method, "REGRESSION: HTTP method changed back to GET - this will cause 404 errors with Azure billing API")
+	assert.NotEqual(t, "GET", req.Raw().Method, "HTTP method must not be GET for Azure pricesheet download endpoint")
+}
+