dev-docs: Go package docs (#958)

* Remove unused package

* Add Go package docs to most packages

Signed-off-by: Daniel Weiße <dw@edgeless.systems>
Signed-off-by: Fabian Kammel <fk@edgeless.systems>
Signed-off-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>
Co-authored-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>
Co-authored-by: Fabian Kammel <fk@edgeless.systems>

upgrade-agent/internal/server/server.go

@@ -0,0 +1,162 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+/*
+Package server implements the gRPC server for the upgrade agent.
+
+The server is responsible for using kubeadm to upgrade the Kubernetes
+release of a Constellation node.
+*/
+package server
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io/fs"
+	"net"
+	"os"
+	"os/exec"
+
+	"github.com/edgelesssys/constellation/v2/internal/constants"
+	"github.com/edgelesssys/constellation/v2/internal/file"
+	"github.com/edgelesssys/constellation/v2/internal/installer"
+	"github.com/edgelesssys/constellation/v2/internal/logger"
+	"github.com/edgelesssys/constellation/v2/internal/versions/components"
+	"github.com/edgelesssys/constellation/v2/upgrade-agent/upgradeproto"
+	"golang.org/x/mod/semver"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+var errInvalidKubernetesVersion = errors.New("invalid kubernetes version")
+
+// Server is the upgrade-agent server.
+type Server struct {
+	file       file.Handler
+	grpcServer serveStopper
+	log        *logger.Logger
+	upgradeproto.UnimplementedUpdateServer
+}
+
+// New creates a new upgrade-agent server.
+func New(log *logger.Logger, fileHandler file.Handler) (*Server, error) {
+	log = log.Named("upgradeServer")
+
+	server := &Server{
+		log:  log,
+		file: fileHandler,
+	}
+
+	grpcServer := grpc.NewServer(
+		log.Named("gRPC").GetServerUnaryInterceptor(),
+	)
+	upgradeproto.RegisterUpdateServer(grpcServer, server)
+
+	server.grpcServer = grpcServer
+	return server, nil
+}
+
+// Run starts the upgrade-agent server on the given port, using the provided protocol and socket address.
+func (s *Server) Run(protocol string, sockAddr string) error {
+	grpcServer := grpc.NewServer()
+
+	upgradeproto.RegisterUpdateServer(grpcServer, s)
+
+	cleanup := func() error {
+		err := os.RemoveAll(sockAddr)
+		if errors.Is(err, fs.ErrNotExist) {
+			return nil
+		} else if err != nil {
+			return err
+		}
+		return nil
+	}
+	if err := cleanup(); err != nil {
+		return fmt.Errorf("failed to clean socket file: %s", err)
+	}
+
+	lis, err := net.Listen(protocol, sockAddr)
+	if err != nil {
+		return fmt.Errorf("failed to listen: %s", err)
+	}
+
+	s.log.Infof("Starting")
+	return grpcServer.Serve(lis)
+}
+
+// Stop stops the upgrade-agent server gracefully.
+func (s *Server) Stop() {
+	s.log.Infof("Stopping")
+
+	s.grpcServer.GracefulStop()
+
+	s.log.Infof("Stopped")
+}
+
+// ExecuteUpdate installs & verifies the provided kubeadm, then executes `kubeadm upgrade plan` & `kubeadm upgrade apply {wanted_Kubernetes_Version}` to upgrade to the specified version.
+func (s *Server) ExecuteUpdate(ctx context.Context, updateRequest *upgradeproto.ExecuteUpdateRequest) (*upgradeproto.ExecuteUpdateResponse, error) {
+	s.log.Infof("Upgrade to Kubernetes version started: %s", updateRequest.WantedKubernetesVersion)
+
+	installer := installer.NewOSInstaller()
+	err := prepareUpdate(ctx, installer, updateRequest)
+	if errors.Is(err, errInvalidKubernetesVersion) {
+		return nil, status.Errorf(codes.Internal, "unable to verify the Kubernetes version %s: %s", updateRequest.WantedKubernetesVersion, err)
+	} else if err != nil {
+		return nil, status.Errorf(codes.Internal, "unable to install the kubeadm binary: %s", err)
+	}
+
+	upgradeCmd := exec.CommandContext(ctx, "kubeadm", "upgrade", "plan")
+	if out, err := upgradeCmd.CombinedOutput(); err != nil {
+		return nil, status.Errorf(codes.Internal, "unable to execute kubeadm upgrade plan: %s: %s", err, string(out))
+	}
+
+	applyCmd := exec.CommandContext(ctx, "kubeadm", "upgrade", "apply", "--yes", updateRequest.WantedKubernetesVersion)
+	if out, err := applyCmd.CombinedOutput(); err != nil {
+		return nil, status.Errorf(codes.Internal, "unable to execute kubeadm upgrade apply: %s: %s", err, string(out))
+	}
+
+	s.log.Infof("Upgrade to Kubernetes version succeeded: %s", updateRequest.WantedKubernetesVersion)
+	return &upgradeproto.ExecuteUpdateResponse{}, nil
+}
+
+// prepareUpdate downloads & installs the specified kubeadm version and verifies the desired Kubernetes version.
+func prepareUpdate(ctx context.Context, installer osInstaller, updateRequest *upgradeproto.ExecuteUpdateRequest) error {
+	// verify Kubernetes version
+	err := verifyVersion(updateRequest.WantedKubernetesVersion)
+	if err != nil {
+		return err
+	}
+
+	// download & install the kubeadm binary
+	return installer.Install(ctx, components.Component{
+		URL:         updateRequest.KubeadmUrl,
+		Hash:        updateRequest.KubeadmHash,
+		InstallPath: constants.KubeadmPath,
+		Extract:     false,
+	})
+}
+
+// verifyVersion verifies the provided Kubernetes version.
+func verifyVersion(version string) error {
+	if !semver.IsValid(version) {
+		return errInvalidKubernetesVersion
+	}
+	return nil
+}
+
+type osInstaller interface {
+	// Install downloads, installs and verifies the kubernetes component.
+	Install(ctx context.Context, kubernetesComponent components.Component) error
+}
+
+type serveStopper interface {
+	// Serve starts the server.
+	Serve(lis net.Listener) error
+	// GracefulStop stops the server and blocks until all requests are done.
+	GracefulStop()
+}