feat(logging): automatic project detection in logging.NewClient() (#9006)

* feat(logging): automatic project detection in logging.NewClient()

* fixed testcase

* Used DetectProjectId as a sentinel value for automatic project detection

Author: gkevinzheng

logging/logging.go

@@ -95,6 +95,15 @@ const (
 
 	// Part of the error message when the payload contains invalid UTF-8 characters.
 	utfErrorString = "string field contains invalid UTF-8"
+
+	// DetectProjectID is a sentinel value that instructs NewClient to detect the
+	// project ID. It is given in place of the projectID argument. NewClient will
+	// use the project ID from the given credentials or the default credentials
+	// (https://developers.google.com/accounts/docs/application-default-credentials)
+	// if no credentials were provided. When providing credentials, not all
+	// options will allow NewClient to extract the project ID. Specifically a JWT
+	// does not have the project ID encoded.
+	DetectProjectID = "*detect-project-id*"
 )
 
 var (
@@ -103,8 +112,9 @@ var (
 	ErrRedirectProtoPayloadNotSupported = errors.New("printEntryToStdout: cannot find valid payload")
 
 	// For testing:
-	now                = time.Now
-	toLogEntryInternal = toLogEntryInternalImpl
+	now                    = time.Now
+	toLogEntryInternal     = toLogEntryInternalImpl
+	detectResourceInternal = detectResource
 
 	// ErrOverflow signals that the number of buffered entries for a Logger
 	// exceeds its BufferLimit.
@@ -148,9 +158,12 @@ type Client struct {
 //	billingAccounts/ACCOUNT_ID
 //	organizations/ORG_ID
 //
-// for backwards compatibility, a string with no '/' is also allowed and is interpreted
+// For backwards compatibility, a string with no '/' is also allowed and is interpreted
 // as a project ID.
 //
+// If logging.DetectProjectId is provided as the parent, the parent will be interpreted as a project
+// ID, and its value will be inferred from the environment.
+//
 // By default NewClient uses WriteScope. To use a different scope, call
 // NewClient using a WithScopes option (see https://godoc.org/google.golang.org/api/option#WithScopes).
 func NewClient(ctx context.Context, parent string, opts ...option.ClientOption) (*Client, error) {
@@ -192,6 +205,13 @@ func NewClient(ctx context.Context, parent string, opts ...option.ClientOption)
 
 func makeParent(parent string) (string, error) {
 	if !strings.ContainsRune(parent, '/') {
+		if parent == DetectProjectID {
+			resource := detectResourceInternal()
+			if resource == nil {
+				return parent, fmt.Errorf("could not determine project ID from environment")
+			}
+			parent = resource.Labels["project_id"]
+		}
 		return "projects/" + parent, nil
 	}
 	prefix := strings.Split(parent, "/")[0]
@@ -301,7 +321,7 @@ func (r *loggerRetryer) Retry(err error) (pause time.Duration, shouldRetry bool)
 // characters: [A-Za-z0-9]; and punctuation characters: forward-slash,
 // underscore, hyphen, and period.
 func (c *Client) Logger(logID string, opts ...LoggerOption) *Logger {
-	r := detectResource()
+	r := detectResourceInternal()
 	if r == nil {
 		r = monitoredResource(c.parent)
 	}

logging/logging_test.go

@@ -1033,6 +1033,74 @@ func TestNonProjectParent(t *testing.T) {
 	}
 }
 
+func TestDetectProjectIdParent(t *testing.T) {
+	ctx := context.Background()
+	initLogs()
+	addr, err := ltesting.NewServer()
+	if err != nil {
+		t.Fatalf("creating fake server: %v", err)
+	}
+	conn, err := grpc.Dial(addr, grpc.WithInsecure())
+	if err != nil {
+		t.Fatalf("dialing %q: %v", addr, err)
+	}
+
+	tests := []struct {
+		name      string
+		resource  *mrpb.MonitoredResource
+		want      string
+		wantError error
+	}{
+		{
+			name: "Test DetectProjectId parent properly set up resource detection",
+			resource: &mrpb.MonitoredResource{
+				Labels: map[string]string{"project_id": testProjectID},
+			},
+			want: "projects/" + testProjectID,
+		},
+		{
+			name:      "Test DetectProjectId parent no resource detected",
+			resource:  nil,
+			wantError: errors.New("could not determine project ID from environment"),
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			// Check if toLogEntryInternal was called with the right parent
+			toLogEntryInternalMock := func(got logging.Entry, l *logging.Logger, parent string, skipLevels int) (*logpb.LogEntry, error) {
+				if parent != test.want {
+					t.Errorf("toLogEntryInternal called with wrong parent. got: %s want: %s", parent, test.want)
+				}
+				return &logpb.LogEntry{}, nil
+			}
+
+			detectResourceMock := func() *mrpb.MonitoredResource {
+				return test.resource
+			}
+
+			realToLogEntryInternal := logging.SetToLogEntryInternal(toLogEntryInternalMock)
+			defer func() { logging.SetToLogEntryInternal(realToLogEntryInternal) }()
+
+			realDetectResourceInternal := logging.SetDetectResourceInternal(detectResourceMock)
+			defer func() { logging.SetDetectResourceInternal(realDetectResourceInternal) }()
+
+			cli, err := logging.NewClient(ctx, logging.DetectProjectID, option.WithGRPCConn(conn))
+			if err != nil && test.wantError == nil {
+				t.Fatalf("Unexpected error: %+v: %v", test.resource, err)
+			}
+			if err == nil && test.wantError != nil {
+				t.Fatalf("Error is expected: %+v: %v", test.resource, test.wantError)
+			}
+			if test.wantError != nil {
+				return
+			}
+
+			cli.Logger(testLogID).LogSync(ctx, logging.Entry{Payload: "hello"})
+		})
+	}
+}
+
 // waitFor calls f repeatedly with exponential backoff, blocking until it returns true.
 // It returns false after a while (if it times out).
 func waitFor(f func() bool) bool {

logging/logging_unexported_test.go

@@ -397,3 +397,8 @@ func SetToLogEntryInternal(f func(Entry, *Logger, string, int) (*logpb.LogEntry,
 	toLogEntryInternal, f = f, toLogEntryInternal
 	return f
 }
+
+func SetDetectResourceInternal(f func() *mrpb.MonitoredResource) func() *mrpb.MonitoredResource {
+	detectResourceInternal, f = f, detectResourceInternal
+	return f
+}