tetra: uses grpc.NewClient in NewClientWithDefaultContext

Switch from grpc.DialContext to grpc.NewClient which does not perform
any I/O and wait lazily for the first RPC call to be made to connect.
This is the way to go as DialContext is getting deprecated and the gRPC
team has been writing that using the other is an anti-pattern.

https://github.com/grpc/grpc-go/blob/master/Documentation/anti-patterns.md

Signed-off-by: Mahe Tardy <[email protected]>

cmd/tetra/common/client.go

@@ -5,6 +5,7 @@ package common
 
 import (
 	"context"
+	"fmt"
 	"os/signal"
 	"syscall"
 	"time"
@@ -61,47 +62,39 @@ func CliRun(fn func(ctx context.Context, cli tetragon.FineGuidanceSensorsClient)
 	CliRunErr(fn, func(_ error) {})
 }
 
-type ConnectedClient struct {
+type ClientWithContext struct {
 	Client tetragon.FineGuidanceSensorsClient
 	Ctx    context.Context
 	conn   *grpc.ClientConn
 	cancel context.CancelFunc
 }
 
 // Close cleanup resources, it closes the connection and cancel the context
-func (c ConnectedClient) Close() {
+func (c ClientWithContext) Close() {
 	c.conn.Close()
 	c.cancel()
 }
 
-// NewConnectedClient return a connected client to a tetragon server, caller
-// must call Close() on the client. On failure to connect, this function calls
-// Fatal() thus stopping execution.
-func NewConnectedClient() ConnectedClient {
-	c := ConnectedClient{}
-	c.Ctx, c.cancel = signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+// NewClientWithDefaultContext return a client to a tetragon server accompanied
+// with an initialized context that can be used for the RPC call, caller must
+// call Close() on the client.
+func NewClientWithDefaultContext() (*ClientWithContext, error) {
+	c := &ClientWithContext{}
 
-	var serverAddr string
-	var err error
+	var timeout context.Context
+	timeout, c.cancel = context.WithTimeout(context.Background(), Timeout)
+	// we don't need the cancelFunc here as calling cancel on timeout, the
+	// parent, will cancel its children.
+	c.Ctx, _ = signal.NotifyContext(timeout, syscall.SIGINT, syscall.SIGTERM)
 
-	backoff := time.Second
-	attempts := 0
-	for {
-		c.conn, serverAddr, err = connect(c.Ctx)
-		if err != nil {
-			if attempts < Retries {
-				// Exponential backoff
-				attempts++
-				logger.GetLogger().WithField("server-address", serverAddr).WithField("attempts", attempts).WithError(err).Error("Connection attempt failed, retrying...")
-				time.Sleep(backoff)
-				backoff *= 2
-				continue
-			}
-			logger.GetLogger().WithField("server-address", serverAddr).WithField("attempts", attempts).WithError(err).Fatal("Failed to connect to server")
-		}
-		break
-	}
+	address := ResolveServerAddress()
 
+	var err error
+	c.conn, err = grpc.NewClient(address, grpc.WithTransportCredentials(insecure.NewCredentials()))
+	if err != nil {
+		return nil, fmt.Errorf("failed to create gRPC client with address %s: %w", address, err)
+	}
 	c.Client = tetragon.NewFineGuidanceSensorsClient(c.conn)
-	return c
+
+	return c, nil
 }

cmd/tetra/tracingpolicy/tracingpolicy.go

@@ -27,7 +27,10 @@ func New() *cobra.Command {
 		Short: "add a new sensor based on a tracing policy",
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			c := common.NewConnectedClient()
+			c, err := common.NewClientWithDefaultContext()
+			if err != nil {
+				return fmt.Errorf("failed create gRPC client: %w", err)
+			}
 			defer c.Close()
 
 			yamlb, err := os.ReadFile(args[0])
@@ -53,10 +56,13 @@ func New() *cobra.Command {
 		Short: "delete a tracing policy",
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			c := common.NewConnectedClient()
+			c, err := common.NewClientWithDefaultContext()
+			if err != nil {
+				return fmt.Errorf("failed create gRPC client: %w", err)
+			}
 			defer c.Close()
 
-			_, err := c.Client.DeleteTracingPolicy(c.Ctx, &tetragon.DeleteTracingPolicyRequest{
+			_, err = c.Client.DeleteTracingPolicy(c.Ctx, &tetragon.DeleteTracingPolicyRequest{
 				Name:      args[0],
 				Namespace: tpDelNamespaceFlag,
 			})
@@ -76,10 +82,13 @@ func New() *cobra.Command {
 		Long:  "Enable a disabled tracing policy. Use disable to re-disable the tracing policy.",
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			c := common.NewConnectedClient()
+			c, err := common.NewClientWithDefaultContext()
+			if err != nil {
+				return fmt.Errorf("failed create gRPC client: %w", err)
+			}
 			defer c.Close()
 
-			_, err := c.Client.EnableTracingPolicy(c.Ctx, &tetragon.EnableTracingPolicyRequest{
+			_, err = c.Client.EnableTracingPolicy(c.Ctx, &tetragon.EnableTracingPolicyRequest{
 				Name:      args[0],
 				Namespace: tpEnableNamespaceFlag,
 			})
@@ -99,10 +108,13 @@ func New() *cobra.Command {
 		Long:  "Disable an enabled tracing policy. Use enable to re-enable the tracing policy.",
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			c := common.NewConnectedClient()
+			c, err := common.NewClientWithDefaultContext()
+			if err != nil {
+				return fmt.Errorf("failed create gRPC client: %w", err)
+			}
 			defer c.Close()
 
-			_, err := c.Client.DisableTracingPolicy(c.Ctx, &tetragon.DisableTracingPolicyRequest{
+			_, err = c.Client.DisableTracingPolicy(c.Ctx, &tetragon.DisableTracingPolicyRequest{
 				Name:      args[0],
 				Namespace: tpDisableNamespaceFlag,
 			})
@@ -130,7 +142,10 @@ func New() *cobra.Command {
 			return nil
 		},
 		RunE: func(cmd *cobra.Command, _ []string) error {
-			c := common.NewConnectedClient()
+			c, err := common.NewClientWithDefaultContext()
+			if err != nil {
+				return fmt.Errorf("failed create gRPC client: %w", err)
+			}
 			defer c.Close()
 
 			res, err := c.Client.ListTracingPolicies(c.Ctx, &tetragon.ListTracingPoliciesRequest{})