[RSDK-8292] Create Single App Connection and Use for Net Appender and Restart Checker

config/reader.go

@@ -181,7 +181,7 @@ func isLocationSecretsEqual(prevCloud, cloud *Cloud) bool {
 	return true
 }
 
-func getTimeoutCtx(ctx context.Context, shouldReadFromCache bool, id string) (context.Context, func()) {
+func GetTimeoutCtx(ctx context.Context, shouldReadFromCache bool, id string) (context.Context, func()) {
 	timeout := readTimeout
 	// When environment indicates we are behind a proxy, bump timeout. Network
 	// operations tend to take longer when behind a proxy.
@@ -257,7 +257,7 @@ func readFromCloud(
 	if !cfg.Cloud.SignalingInsecure && (checkForNewCert || tls.certificate == "" || tls.privateKey == "") {
 		logger.Debug("reading tlsCertificate from the cloud")
 
-		ctxWithTimeout, cancel := getTimeoutCtx(ctx, shouldReadFromCache, cloudCfg.ID)
+		ctxWithTimeout, cancel := GetTimeoutCtx(ctx, shouldReadFromCache, cloudCfg.ID)
 		certData, err := readCertificateDataFromCloudGRPC(ctxWithTimeout, cloudCfg, logger)
 		if err != nil {
 			cancel()
@@ -609,7 +609,7 @@ func processConfig(unprocessedConfig *Config, fromCloud bool, logger logging.Log
 func getFromCloudOrCache(ctx context.Context, cloudCfg *Cloud, shouldReadFromCache bool, logger logging.Logger) (*Config, bool, error) {
 	var cached bool
 
-	ctxWithTimeout, cancel := getTimeoutCtx(ctx, shouldReadFromCache, cloudCfg.ID)
+	ctxWithTimeout, cancel := GetTimeoutCtx(ctx, shouldReadFromCache, cloudCfg.ID)
 	defer cancel()
 
 	cfg, errorShouldCheckCache, err := getFromCloudGRPC(ctxWithTimeout, cloudCfg, logger)

grpc/app_conn.go

@@ -0,0 +1,85 @@
+package grpc
+
+import (
+	"context"
+	"net/url"
+	"time"
+
+	"github.com/pkg/errors"
+
+	"go.viam.com/rdk/config"
+	"go.viam.com/rdk/logging"
+	"go.viam.com/utils/rpc"
+)
+
+type AppConn struct {
+	ReconfigurableClientConn
+
+	// Err stores the most recent error returned by the serialized dial attempts running in the background. It can also be used to tell
+	// whether dial attempts are currently happening; If err is a non-nil value, dial attempts have stopped. Accesses to Err should respect
+	// ReconfigurableClientConn.connMu
+	Err error
+}
+
+func NewAppConn(ctx context.Context, cloud *config.Cloud, logger logging.Logger) (*AppConn, error) {
+	grpcURL, err := url.Parse(cloud.AppAddress)
+	if err != nil {
+		return nil, err
+	}
+
+	dialOpts := dialOpts(cloud)
+
+	if grpcURL.Scheme == "http" {
+		dialOpts = append(dialOpts, rpc.WithInsecure())
+	}
+
+	appConn := &AppConn{}
+
+	// a lock is not necessary here because this call is blocking
+	appConn.conn, err = rpc.DialDirectGRPC(ctx, grpcURL.Host, logger, dialOpts...)
+	if err != nil {
+		if errors.Is(err, context.DeadlineExceeded) {
+			go func() {
+				for {
+					appConn.connMu.Lock()
+
+					ctxWithTimeOut, ctxWithTimeOutCancel := context.WithTimeout(context.Background(), 5*time.Second)
+
+					appConn.conn, err = rpc.DialDirectGRPC(ctxWithTimeOut, grpcURL.Host, logger, dialOpts...)
+					if errors.Is(err, context.DeadlineExceeded) {
+						appConn.connMu.Unlock()
+
+						// only dial again if previous attempt timed out
+						continue
+					}
+
+					ctxWithTimeOutCancel()
+
+					appConn.Err = err
+
+					break
+				}
+
+				appConn.connMu.Unlock()
+			}()
+		} else {
+			return nil, err
+		}
+	}
+
+	return appConn, nil
+}
+
+func dialOpts(cloud *config.Cloud) []rpc.DialOption {
+	dialOpts := make([]rpc.DialOption, 0, 2)
+	// Only add credentials when secret is set.
+	if cloud.Secret != "" {
+		dialOpts = append(dialOpts, rpc.WithEntityCredentials(cloud.ID,
+			rpc.Credentials{
+				Type:    "robot-secret",
+				Payload: cloud.Secret,
+			},
+		))
+	}
+	return dialOpts
+}

web/server/entrypoint.go

@@ -24,6 +24,7 @@ import (
 	"go.viam.com/utils/rpc"
 
 	"go.viam.com/rdk/config"
+	"go.viam.com/rdk/grpc"
 	"go.viam.com/rdk/logging"
 	"go.viam.com/rdk/resource"
 	"go.viam.com/rdk/robot"
@@ -191,13 +192,16 @@ func RunServer(ctx context.Context, args []string, _ logging.Logger) (err error)
 	// Start remote logging with config from disk.
 	// This is to ensure we make our best effort to write logs for failures loading the remote config.
 	if cfgFromDisk.Cloud != nil && (cfgFromDisk.Cloud.LogPath != "" || cfgFromDisk.Cloud.AppAddress != "") {
+		ctxWithTimeout, ctxWithTimeoutCancel := config.GetTimeoutCtx(ctx, true, cfgFromDisk.Cloud.ID)
+		appConn, err := grpc.NewAppConn(ctxWithTimeout, cfgFromDisk.Cloud, logger) // TODO(RSDK-8292): [q] what logger should I pass here?
+		ctxWithTimeoutCancel()
 		netAppender, err := logging.NewNetAppender(
 			&logging.CloudConfig{
 				AppAddress: cfgFromDisk.Cloud.AppAddress,
 				ID:         cfgFromDisk.Cloud.ID,
 				Secret:     cfgFromDisk.Cloud.Secret,
 			},
-			nil, false, logger.Sublogger("networking").Sublogger("netlogger"),
+			appConn, false, logger.Sublogger("networking").Sublogger("netlogger"),
 		)
 		if err != nil {
 			return err