rbd: add framework for CSI-Addons Identity Service

Add a new CSI-Addons Server and empty Identity Service for the RBD
plugin. The implementation of the Identity Service procedure calls will
be done in other PRs.

Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/csi-addons/rbd/identity.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package rbd
+
+import (
+	"context"
+
+	"github.com/csi-addons/spec/lib/go/identity"
+	"google.golang.org/grpc"
+)
+
+// IdentityServer struct of rbd CSI driver with supported methods of CSI
+// identity server spec.
+type IdentityServer struct {
+	*identity.UnimplementedIdentityServer
+}
+
+func (is *IdentityServer) RegisterService(server grpc.ServiceRegistrar) {
+	identity.RegisterIdentityServer(server, is)
+}
+
+// GetIdentity returns available capabilities of the rbd driver.
+func (is *IdentityServer) GetIdentity(
+	ctx context.Context,
+	req *identity.GetIdentityRequest) (*identity.GetIdentityResponse, error) {
+	return nil, nil
+}
+
+// GetCapabilities returns available capabilities of the rbd driver.
+func (is *IdentityServer) GetCapabilities(
+	ctx context.Context,
+	req *identity.GetCapabilitiesRequest) (*identity.GetCapabilitiesResponse, error) {
+	return nil, nil
+}
+
+// GetCapabilities returns available capabilities of the rbd driver.
+func (is *IdentityServer) Probe(
+	ctx context.Context,
+	req *identity.ProbeRequest) (*identity.ProbeResponse, error) {
+	return nil, nil
+}

internal/csi-addons/server/server.go

@@ -0,0 +1,131 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"net/url"
+	"os"
+
+	"google.golang.org/grpc"
+
+	"github.com/ceph/ceph-csi/internal/util/log"
+)
+
+var ErrNoUDS = errors.New("no UNIX domain socket")
+
+// CSIAddonsService is the interface that is required to be implemented so that
+// the CSIAddonsServer can register the service by calling RegisterService().
+type CSIAddonsService interface {
+	// RegisterService is called by the CSIAddonsServer to add a CSI-Addons
+	// service that can handle requests.
+	RegisterService(server grpc.ServiceRegistrar)
+}
+
+// CSIAddonsServer is the gRPC server that listens on an endpoint (UNIX domain
+// socket) where the CSI-Addons requests come in.
+type CSIAddonsServer struct {
+	// URL components to listen on the UNIX domain socket
+	scheme string
+	path   string
+
+	// state of the CSIAddonsServer
+	server   *grpc.Server
+	services []CSIAddonsService
+}
+
+// NewCSIAddonsServer create a new CSIAddonsServer on the given endpoint. The
+// endpoint should be a URL. Only UNIX domain sockets are supported.
+func NewCSIAddonsServer(endpoint string) (*CSIAddonsServer, error) {
+	cas := &CSIAddonsServer{}
+
+	if cas.services == nil {
+		cas.services = make([]CSIAddonsService, 0)
+	}
+
+	u, err := url.Parse(endpoint)
+	if err != nil {
+		return nil, err
+	}
+
+	if u.Scheme != "unix" {
+		return nil, fmt.Errorf("%w: %s", ErrNoUDS, endpoint)
+	}
+
+	cas.scheme = u.Scheme
+	cas.path = u.Path
+
+	return cas, nil
+}
+
+// RegisterService takes the CSIAddonsService and registers it with the
+// CSIAddonsServer gRPC server. This function should be called before Start,
+// where the services are registered on the internal gRPC server.
+func (cas *CSIAddonsServer) RegisterService(svc CSIAddonsService) {
+	cas.services = append(cas.services, svc)
+}
+
+// Start creates the internal gRPC server, and registers the CSIAddonsServices.
+// The internal gRPC server is started in it's own go-routine when no error is
+// returned.
+func (cas *CSIAddonsServer) Start() error {
+	// create the gRPC server and register services
+	cas.server = grpc.NewServer()
+
+	for _, svc := range cas.services {
+		svc.RegisterService(cas.server)
+	}
+
+	// setup the UNIX domain socket
+	if e := os.Remove(cas.path); e != nil && !os.IsNotExist(e) {
+		return fmt.Errorf("failed to remove %q: %w", cas.path, e)
+	}
+
+	listener, err := net.Listen(cas.scheme, cas.path)
+	if err != nil {
+		return fmt.Errorf("failed to listen on %q: %w", cas.path, err)
+	}
+
+	go cas.serve(listener)
+
+	return nil
+}
+
+// serve starts the actual process of listening for requests on the gRPC
+// server. This is a blocking call, so it should get executed in a go-routine.
+func (cas *CSIAddonsServer) serve(listener net.Listener) {
+	log.DefaultLog("listening for CSI-Addons requests on address: %#v", listener.Addr())
+
+	// start to serve requests
+	err := cas.server.Serve(listener)
+	if err != nil && !errors.Is(err, grpc.ErrServerStopped) {
+		log.FatalLogMsg("failed to setup CSI-Addons server: %v", err)
+	}
+
+	log.DefaultLog("the CSI-Addons server at %q has been stopped", listener.Addr())
+}
+
+// Stop can be used to stop the internal gRPC server.
+func (cas *CSIAddonsServer) Stop() {
+	if cas.server == nil {
+		return
+	}
+
+	cas.server.GracefulStop()
+}

internal/csi-addons/server/server_test.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2021 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewCSIAddonsServer(t *testing.T) {
+	t.Parallel()
+
+	t.Run("valid endpoint", func(t *testing.T) {
+		t.Parallel()
+
+		cas, err := NewCSIAddonsServer("unix:///tmp/csi-addons.sock")
+		require.NoError(t, err)
+		require.NotNil(t, cas)
+	})
+
+	t.Run("empty endpoint", func(t *testing.T) {
+		t.Parallel()
+
+		cas, err := NewCSIAddonsServer("")
+		require.Error(t, err)
+		assert.Nil(t, cas)
+	})
+
+	t.Run("no UDS endpoint", func(t *testing.T) {
+		t.Parallel()
+
+		cas, err := NewCSIAddonsServer("endpoint at /tmp/...")
+		require.Error(t, err)
+		assert.Nil(t, cas)
+	})
+}