[breaking] Refactor `DownloadProgress` gRPC message: more clear field meaning. (#1875)

* Refactored DownloadProgress protocol

* Updated integration tests

* Do not create overly verbose errors

* Updated docs

* Update rpc/cc/arduino/cli/commands/v1/commands.proto
Co-authored-by: per1234 <accounts@perglass.com>
Co-authored-by: per1234 <accounts@perglass.com>

arduino/cores/packagemanager/download.go

@@ -127,12 +127,7 @@ func (pme *Explorer) DownloadToolRelease(tool *cores.ToolRelease, config *downlo
 			Message: tr("Error downloading tool %s", tool),
 			Cause:   errors.New(tr("no versions available for the current OS"))}
 	}
-	if err := resource.Download(pme.DownloadDir, config, tool.String(), progressCB); err != nil {
-		return &arduino.FailedDownloadError{
-			Message: tr("Error downloading tool %s", tool),
-			Cause:   err}
-	}
-	return nil
+	return resource.Download(pme.DownloadDir, config, tool.String(), progressCB)
 }
 
 // DownloadPlatformRelease downloads a PlatformRelease. If the platform is already downloaded a

arduino/httpclient/httpclient.go

@@ -32,7 +32,16 @@ var tr = i18n.Tr
 
 // DownloadFile downloads a file from a URL into the specified path. An optional config and options may be passed (or nil to use the defaults).
 // A DownloadProgressCB callback function must be passed to monitor download progress.
-func DownloadFile(path *paths.Path, URL string, label string, downloadCB rpc.DownloadProgressCB, config *downloader.Config, options ...downloader.DownloadOptions) error {
+func DownloadFile(path *paths.Path, URL string, label string, downloadCB rpc.DownloadProgressCB, config *downloader.Config, options ...downloader.DownloadOptions) (returnedError error) {
+	downloadCB.Start(URL, label)
+	defer func() {
+		if returnedError == nil {
+			downloadCB.End(true, "")
+		} else {
+			downloadCB.End(false, returnedError.Error())
+		}
+	}()
+
 	if config == nil {
 		c, err := GetDownloaderConfig()
 		if err != nil {
@@ -45,15 +54,9 @@ func DownloadFile(path *paths.Path, URL string, label string, downloadCB rpc.Dow
 	if err != nil {
 		return err
 	}
-	downloadCB(&rpc.DownloadProgress{
-		File:      label,
-		Url:       d.URL,
-		TotalSize: d.Size(),
-	})
-	defer downloadCB(&rpc.DownloadProgress{Completed: true})
 
 	err = d.RunAndPoll(func(downloaded int64) {
-		downloadCB(&rpc.DownloadProgress{Downloaded: downloaded})
+		downloadCB.Update(downloaded, d.Size())
 	}, 250*time.Millisecond)
 	if err != nil {
 		return err
@@ -61,7 +64,8 @@ func DownloadFile(path *paths.Path, URL string, label string, downloadCB rpc.Dow
 
 	// The URL is not reachable for some reason
 	if d.Resp.StatusCode >= 400 && d.Resp.StatusCode <= 599 {
-		return &arduino.FailedDownloadError{Message: tr("Server responded with: %s", d.Resp.Status)}
+		msg := tr("Server responded with: %s", d.Resp.Status)
+		return &arduino.FailedDownloadError{Message: msg}
 	}
 
 	return nil

arduino/resources/download.go

@@ -44,12 +44,8 @@ func (r *DownloadResource) Download(downloadDir *paths.Path, config *downloader.
 			}
 		} else {
 			// File is cached, nothing to do here
-
-			// This signal means that the file is already downloaded
-			downloadCB(&rpc.DownloadProgress{
-				File:      label,
-				Completed: true,
-			})
+			downloadCB.Start(r.URL, label)
+			downloadCB.End(true, tr("%s already downloaded", label))
 			return nil
 		}
 	} else {

cli/core/search.go

@@ -67,9 +67,7 @@ func runSearchCommand(cmd *cobra.Command, args []string) {
 	}
 
 	if indexesNeedUpdating(indexUpdateInterval) {
-		err := commands.UpdateIndex(context.Background(), &rpc.UpdateIndexRequest{Instance: inst},
-			output.ProgressBar(),
-			output.PrintErrorFromDownloadResult(tr("Error updating index")))
+		err := commands.UpdateIndex(context.Background(), &rpc.UpdateIndexRequest{Instance: inst}, output.ProgressBar())
 		if err != nil {
 			os.Exit(errorcodes.ErrGeneric)
 		}

cli/core/update_index.go

@@ -20,6 +20,7 @@ import (
 	"os"
 
 	"github.com/arduino/arduino-cli/cli/errorcodes"
+	"github.com/arduino/arduino-cli/cli/feedback"
 	"github.com/arduino/arduino-cli/cli/instance"
 	"github.com/arduino/arduino-cli/cli/output"
 	"github.com/arduino/arduino-cli/commands"
@@ -44,10 +45,9 @@ func runUpdateIndexCommand(cmd *cobra.Command, args []string) {
 	inst := instance.CreateInstanceAndRunFirstUpdate()
 	logrus.Info("Executing `arduino-cli core update-index`")
 
-	err := commands.UpdateIndex(context.Background(), &rpc.UpdateIndexRequest{Instance: inst},
-		output.ProgressBar(),
-		output.PrintErrorFromDownloadResult(tr("Error updating index")))
+	err := commands.UpdateIndex(context.Background(), &rpc.UpdateIndexRequest{Instance: inst}, output.ProgressBar())
 	if err != nil {
+		feedback.Error(err)
 		os.Exit(errorcodes.ErrGeneric)
 	}
 }

cli/instance/instance.go

@@ -157,8 +157,7 @@ func FirstUpdate(instance *rpc.Instance) error {
 				Instance:                   instance,
 				IgnoreCustomPackageIndexes: true,
 			},
-			output.ProgressBar(),
-			output.PrintErrorFromDownloadResult(tr("Error updating index")))
+			output.ProgressBar())
 		if err != nil {
 			return err
 		}

cli/output/rpc_progress.go

@@ -17,6 +17,7 @@ package output
 
 import (
 	"fmt"
+	"sync"
 
 	"github.com/arduino/arduino-cli/cli/feedback"
 	"github.com/arduino/arduino-cli/i18n"
@@ -41,21 +42,6 @@ func ProgressBar() rpc.DownloadProgressCB {
 	}
 }
 
-// PrintErrorFromDownloadResult returns a DownloadResultCB that only prints
-// the errors with the give message prefixed.
-func PrintErrorFromDownloadResult(msg string) rpc.DownloadResultCB {
-	if OutputFormat != "json" {
-		return func(res *rpc.DownloadResult) {
-			if !res.GetSuccessful() {
-				feedback.Errorf("%s: %s", msg, res.GetError())
-			}
-		}
-	}
-	return func(res *rpc.DownloadResult) {
-		// XXX: Output result in JSON?
-	}
-}
-
 // TaskProgress returns a TaskProgressCB that prints the task progress.
 // If JSON output format has been selected, the callback outputs nothing.
 func TaskProgress() rpc.TaskProgressCB {
@@ -70,25 +56,39 @@ func TaskProgress() rpc.TaskProgressCB {
 // NewDownloadProgressBarCB creates a progress bar callback that outputs a progress
 // bar on the terminal
 func NewDownloadProgressBarCB() func(*rpc.DownloadProgress) {
+	var mux sync.Mutex
 	var bar *pb.ProgressBar
-	var prefix string
+	var label string
+	started := false
 	return func(curr *rpc.DownloadProgress) {
+		mux.Lock()
+		defer mux.Unlock()
+
 		// fmt.Printf(">>> %v\n", curr)
-		if filename := curr.GetFile(); filename != "" {
-			if curr.GetCompleted() {
-				fmt.Println(tr("%s already downloaded", filename))
-				return
-			}
-			prefix = filename
-			bar = pb.StartNew(int(curr.GetTotalSize()))
-			bar.Prefix(prefix)
+		if start := curr.GetStart(); start != nil {
+			label = start.GetLabel()
+			bar = pb.New(0)
+			bar.Prefix(label)
 			bar.SetUnits(pb.U_BYTES)
 		}
-		if curr.GetDownloaded() != 0 {
-			bar.Set(int(curr.GetDownloaded()))
+		if update := curr.GetUpdate(); update != nil {
+			bar.SetTotal64(update.GetTotalSize())
+			if !started {
+				bar.Start()
+				started = true
+			}
+			bar.Set64(update.GetDownloaded())
 		}
-		if curr.GetCompleted() {
-			bar.FinishPrintOver(tr("%s downloaded", prefix))
+		if end := curr.GetEnd(); end != nil {
+			msg := end.GetMessage()
+			if end.GetSuccess() && msg == "" {
+				msg = tr("downloaded")
+			}
+			if started {
+				bar.FinishPrintOver(label + " " + msg)
+			} else {
+				feedback.Print(label + " " + msg)
+			}
 		}
 	}
 }

cli/update/update.go

@@ -56,9 +56,9 @@ func runUpdateCommand(cmd *cobra.Command, args []string) {
 	inst := instance.CreateInstanceAndRunFirstUpdate()
 	logrus.Info("Executing `arduino-cli update`")
 
-	err := commands.UpdateCoreLibrariesIndex(context.Background(), &rpc.UpdateCoreLibrariesIndexRequest{Instance: inst},
-		output.ProgressBar(),
-		output.PrintErrorFromDownloadResult(tr("Error updating index")))
+	err := commands.UpdateCoreLibrariesIndex(context.Background(),
+		&rpc.UpdateCoreLibrariesIndexRequest{Instance: inst},
+		output.ProgressBar())
 	if err != nil {
 		feedback.Errorf(tr("Error updating core and libraries index: %v"), err)
 		os.Exit(errorcodes.ErrGeneric)

commands/daemon/daemon.go

@@ -162,12 +162,7 @@ func (s *ArduinoCoreServerImpl) Destroy(ctx context.Context, req *rpc.DestroyReq
 // UpdateIndex FIXMEDOC
 func (s *ArduinoCoreServerImpl) UpdateIndex(req *rpc.UpdateIndexRequest, stream rpc.ArduinoCoreService_UpdateIndexServer) error {
 	err := commands.UpdateIndex(stream.Context(), req,
-		func(p *rpc.DownloadProgress) {
-			stream.Send(&rpc.UpdateIndexResponse{Message: &rpc.UpdateIndexResponse_DownloadProgress{DownloadProgress: p}})
-		},
-		func(r *rpc.DownloadResult) {
-			stream.Send(&rpc.UpdateIndexResponse{Message: &rpc.UpdateIndexResponse_DownloadResult{DownloadResult: r}})
-		},
+		func(p *rpc.DownloadProgress) { stream.Send(&rpc.UpdateIndexResponse{DownloadProgress: p}) },
 	)
 	return convertErrorToRPCStatus(err)
 }
@@ -187,7 +182,6 @@ func (s *ArduinoCoreServerImpl) UpdateLibrariesIndex(req *rpc.UpdateLibrariesInd
 func (s *ArduinoCoreServerImpl) UpdateCoreLibrariesIndex(req *rpc.UpdateCoreLibrariesIndexRequest, stream rpc.ArduinoCoreService_UpdateCoreLibrariesIndexServer) error {
 	err := commands.UpdateCoreLibrariesIndex(stream.Context(), req,
 		func(p *rpc.DownloadProgress) { stream.Send(&rpc.UpdateCoreLibrariesIndexResponse{DownloadProgress: p}) },
-		func(res *rpc.DownloadResult) { /* ignore */ },
 	)
 	if err != nil {
 		return convertErrorToRPCStatus(err)

commands/instances.go

@@ -19,7 +19,7 @@ import (
 	"context"
 	"fmt"
 	"net/url"
-	"os"
+	"path/filepath"
 	"strings"
 	"sync"
 
@@ -490,7 +490,7 @@ func UpdateLibrariesIndex(ctx context.Context, req *rpc.UpdateLibrariesIndexRequ
 }
 
 // UpdateIndex FIXMEDOC
-func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rpc.DownloadProgressCB, downloadResultCB rpc.DownloadResultCB) error {
+func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rpc.DownloadProgressCB) error {
 	if instances.GetInstance(req.GetInstance().GetId()) == nil {
 		return &arduino.InvalidInstanceError{}
 	}
@@ -504,14 +504,12 @@ func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rp
 
 	failed := false
 	for _, u := range urls {
-		logrus.Info("URL: ", u)
 		URL, err := utils.URLParse(u)
 		if err != nil {
 			logrus.Warnf("unable to parse additional URL: %s", u)
-			downloadResultCB(&rpc.DownloadResult{
-				Url:   u,
-				Error: fmt.Sprintf("%s: %v", tr("Unable to parse URL"), err),
-			})
+			msg := fmt.Sprintf("%s: %v", tr("Unable to parse URL"), err)
+			downloadCB.Start(u, tr("Downloading index: %s", u))
+			downloadCB.End(false, msg)
 			failed = true
 			continue
 		}
@@ -519,49 +517,26 @@ func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rp
 		logrus.WithField("url", URL).Print("Updating index")
 
 		if URL.Scheme == "file" {
+			downloadCB.Start(u, tr("Downloading index: %s", filepath.Base(URL.Path)))
 			path := paths.New(URL.Path)
 			if _, err := packageindex.LoadIndexNoSign(path); err != nil {
-				downloadResultCB(&rpc.DownloadResult{
-					Url:   u,
-					Error: fmt.Sprintf("%s: %v", tr("Invalid package index in %s", path), err),
-				})
+				msg := fmt.Sprintf("%s: %v", tr("Invalid package index in %s", path), err)
+				downloadCB.End(false, msg)
 				failed = true
-				continue
+			} else {
+				downloadCB.End(true, "")
 			}
-
-			fi, _ := os.Stat(path.String())
-			downloadCB(&rpc.DownloadProgress{
-				File:      tr("Downloading index: %s", path.Base()),
-				TotalSize: fi.Size(),
-			})
-			downloadCB(&rpc.DownloadProgress{Completed: true})
-			downloadResultCB(&rpc.DownloadResult{
-				Url:        u,
-				Successful: true,
-			})
 			continue
 		}
 
-		indexResource := resources.IndexResource{
-			URL: URL,
-		}
+		indexResource := resources.IndexResource{URL: URL}
 		if strings.HasSuffix(URL.Host, "arduino.cc") && strings.HasSuffix(URL.Path, ".json") {
 			indexResource.SignatureURL, _ = url.Parse(u) // should not fail because we already parsed it
 			indexResource.SignatureURL.Path += ".sig"
 		}
 		if err := indexResource.Download(indexpath, downloadCB); err != nil {
-			downloadResultCB(&rpc.DownloadResult{
-				Url:   u,
-				Error: err.Error(),
-			})
 			failed = true
-			continue
 		}
-
-		downloadResultCB(&rpc.DownloadResult{
-			Url:        u,
-			Successful: true,
-		})
 	}
 
 	if failed {
@@ -571,17 +546,13 @@ func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rp
 }
 
 // UpdateCoreLibrariesIndex updates both Cores and Libraries indexes
-func UpdateCoreLibrariesIndex(ctx context.Context, req *rpc.UpdateCoreLibrariesIndexRequest, downloadCB rpc.DownloadProgressCB, downloadResultCB rpc.DownloadResultCB) error {
-	err := UpdateIndex(ctx, &rpc.UpdateIndexRequest{
-		Instance: req.Instance,
-	}, downloadCB, downloadResultCB)
+func UpdateCoreLibrariesIndex(ctx context.Context, req *rpc.UpdateCoreLibrariesIndexRequest, downloadCB rpc.DownloadProgressCB) error {
+	err := UpdateIndex(ctx, &rpc.UpdateIndexRequest{Instance: req.Instance}, downloadCB)
 	if err != nil {
 		return err
 	}
 
-	err = UpdateLibrariesIndex(ctx, &rpc.UpdateLibrariesIndexRequest{
-		Instance: req.Instance,
-	}, downloadCB)
+	err = UpdateLibrariesIndex(ctx, &rpc.UpdateLibrariesIndexRequest{Instance: req.Instance}, downloadCB)
 	if err != nil {
 		return err
 	}

docs/UPGRADING.md

@@ -76,55 +76,96 @@ replacement.
 
 ### Breaking changes in UpdateIndex API (both gRPC and go-lang)
 
-The gRPC message `cc.arduino.cli.commands.v1.UpdateIndexResponse` has been changed from:
+The gRPC message `cc.arduino.cli.commands.v1.DownloadProgress` has been changed from:
 
 ```
-message UpdateIndexResponse {
-  // Progress of the platforms index download.
-  DownloadProgress download_progress = 1;
+message DownloadProgress {
+  // URL of the download.
+  string url = 1;
+  // The file being downloaded.
+  string file = 2;
+  // Total size of the file being downloaded.
+  int64 total_size = 3;
+  // Size of the downloaded portion of the file.
+  int64 downloaded = 4;
+  // Whether the download is complete.
+  bool completed = 5;
 }
 ```
 
 to
 
 ```
-message UpdateIndexResponse {
+message DownloadProgress {
   oneof message {
-    // Progress of the platforms index download.
-    DownloadProgress download_progress = 1;
-    // Report of the index update downloads.
-    DownloadResult download_result = 2;
+    DownloadProgressStart start = 1;
+    DownloadProgressUpdate update = 2;
+    DownloadProgressEnd end = 3;
   }
 }
 
-message DownloadResult {
-  // Index URL.
+message DownloadProgressStart {
+  // URL of the download.
   string url = 1;
-  // Download result: true if successful, false if an error occurred.
-  bool successful = 2;
-  // Download error details.
-  string error = 3;
+  // The label to display on the progress bar.
+  string label = 2;
 }
+
+message DownloadProgressUpdate {
+  // Size of the downloaded portion of the file.
+  int64 downloaded = 1;
+  // Total size of the file being downloaded.
+  int64 total_size = 2;
+}
+
+message DownloadProgressEnd {
+  // True if the download is successful
+  bool success = 1;
+  // Info or error message, depending on the value of 'success'. Some examples:
+  // "File xxx already downloaded" or "Connection timeout"
+  string message = 2;
+}
+```
+
+The new message format allows a better handling of the progress update reports on downloads. Every download now will
+report a sequence of message as follows:
+
+```
+DownloadProgressStart{url="https://...", label="Downloading package index..."}
+DownloadProgressUpdate{downloaded=0, total_size=103928}
+DownloadProgressUpdate{downloaded=29380, total_size=103928}
+DownloadProgressUpdate{downloaded=69540, total_size=103928}
+DownloadProgressEnd{success=true, message=""}
+```
+
+or if an error occurs:
+
+```
+DownloadProgressStart{url="https://...", label="Downloading package index..."}
+DownloadProgressUpdate{downloaded=0, total_size=103928}
+DownloadProgressEnd{success=false, message="Server closed connection"}
+```
+
+or if the file is already cached:
+
+```
+DownloadProgressStart{url="https://...", label="Downloading package index..."}
+DownloadProgressEnd{success=true, message="Index already downloaded"}
 ```
 
-even if not strictly a breaking change it's worth noting that the detailed error message is now streamed in the
-response. About the go-lang API the following functions in `github.com/arduino/arduino-cli/commands`:
+About the go-lang API the following functions in `github.com/arduino/arduino-cli/commands`:
 
 ```go
 func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rpc.DownloadProgressCB) (*rpc.UpdateIndexResponse, error) { ... }
-func UpdateCoreLibrariesIndex(ctx context.Context, req *rpc.UpdateCoreLibrariesIndexRequest, downloadCB rpc.DownloadProgressCB) error { ... }
 ```
 
 have changed their signature to:
 
 ```go
 func UpdateIndex(ctx context.Context, req *rpc.UpdateIndexRequest, downloadCB rpc.DownloadProgressCB, downloadResultCB rpc.DownloadResultCB) error { ... }
-func UpdateCoreLibrariesIndex(ctx context.Context, req *rpc.UpdateCoreLibrariesIndexRequest, downloadCB rpc.DownloadProgressCB, downloadResultCB rpc.DownloadResultCB) error { ... }
 ```
 
-`UpdateIndex` do not return anymore the latest `UpdateIndexResponse` (it was always empty). Both `UpdateIndex` and
-`UpdateCoreLibrariesIndex` now accepts an `rpc.DownloadResultCB` to get download results, you can pass an empty callback
-if you're not interested in the error details.
+`UpdateIndex` do not return anymore the latest `UpdateIndexResponse` (beacuse it was always empty).
 
 ## 0.27.0
 

internal/integrationtest/daemon/daemon_core_test.go

@@ -41,59 +41,38 @@ func TestDaemonCoreUpdateIndex(t *testing.T) {
 			` "http://downloads.arduino.cc/package_inexistent_index.json"]`)
 	require.NoError(t, err)
 
+	analyzeUpdateIndexClient := func(cl commands.ArduinoCoreService_UpdateIndexClient) (error, map[string]*commands.DownloadProgressEnd) {
+		analyzer := NewDownloadProgressAnalyzer(t)
+		for {
+			msg, err := cl.Recv()
+			// fmt.Println("DOWNLOAD>", msg)
+			if err == io.EOF {
+				return nil, analyzer.Results
+			}
+			if err != nil {
+				return err, analyzer.Results
+			}
+			require.NoError(t, err)
+			analyzer.Process(msg.GetDownloadProgress())
+		}
+	}
+
 	{
 		cl, err := grpcInst.UpdateIndex(context.Background(), true)
 		require.NoError(t, err)
-		res, err := analyzeUpdateIndexStream(t, cl)
+		err, res := analyzeUpdateIndexClient(cl)
 		require.NoError(t, err)
 		require.Len(t, res, 1)
-		require.True(t, res["https://downloads.arduino.cc/packages/package_index.tar.bz2"].Successful)
+		require.True(t, res["https://downloads.arduino.cc/packages/package_index.tar.bz2"].Success)
 	}
 	{
 		cl, err := grpcInst.UpdateIndex(context.Background(), false)
 		require.NoError(t, err)
-		res, err := analyzeUpdateIndexStream(t, cl)
+		err, res := analyzeUpdateIndexClient(cl)
 		require.Error(t, err)
 		require.Len(t, res, 3)
-		require.True(t, res["https://downloads.arduino.cc/packages/package_index.tar.bz2"].Successful)
-		require.True(t, res["http://arduino.esp8266.com/stable/package_esp8266com_index.json"].Successful)
-		require.False(t, res["http://downloads.arduino.cc/package_inexistent_index.json"].Successful)
-	}
-}
-
-// analyzeUpdateIndexStream runs an update index checking if the sequence of DownloadProgress and
-// DownloadResult messages is correct. It returns a map reporting all the DownloadResults messages
-// received (it maps urls to DownloadResults).
-func analyzeUpdateIndexStream(t *testing.T, cl commands.ArduinoCoreService_UpdateIndexClient) (map[string]*commands.DownloadResult, error) {
-	ongoingDownload := ""
-	results := map[string]*commands.DownloadResult{}
-	for {
-		msg, err := cl.Recv()
-		if err == io.EOF {
-			return results, nil
-		}
-		if err != nil {
-			return results, err
-		}
-		require.NoError(t, err)
-		fmt.Printf("UPDATE> %+v\n", msg)
-		if progress := msg.GetDownloadProgress(); progress != nil {
-			if progress.Url != "" && progress.Url != ongoingDownload {
-				require.Empty(t, ongoingDownload, "DownloadProgress: started a download without 'completing' the previous one")
-				ongoingDownload = progress.Url
-			}
-			if progress.Completed {
-				require.NotEmpty(t, ongoingDownload, "DownloadProgress: received a 'completed' notification but never initiated a download")
-				ongoingDownload = ""
-			}
-			if progress.Downloaded > 0 {
-				require.NotEmpty(t, ongoingDownload, "DownloadProgress: received a download update but never initiated a download")
-			}
-		} else if result := msg.GetDownloadResult(); result != nil {
-			require.Empty(t, ongoingDownload, "DownloadResult: got a download result without completing the current download first")
-			results[result.Url] = result
-		} else {
-			require.FailNow(t, "DownloadProgress: received an empty message (without a Progress or a Result)")
-		}
+		require.True(t, res["https://downloads.arduino.cc/packages/package_index.tar.bz2"].Success)
+		require.True(t, res["http://arduino.esp8266.com/stable/package_esp8266com_index.json"].Success)
+		require.False(t, res["http://downloads.arduino.cc/package_inexistent_index.json"].Success)
 	}
 }

internal/integrationtest/daemon/download_progress_test.go

+// This file is part of arduino-cli.
+//
+// Copyright 2022 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to license@arduino.cc.
+
+package daemon_test
+
+import (
+	"testing"
+
+	"github.com/arduino/arduino-cli/rpc/cc/arduino/cli/commands/v1"
+	"github.com/stretchr/testify/require"
+)
+
+// DownloadProgressAnalyzer analyzes DownloadProgress messages for consistency
+type DownloadProgressAnalyzer struct {
+	t               *testing.T
+	ongoingDownload string
+	Results         map[string]*commands.DownloadProgressEnd
+}
+
+// NewDownloadProgressAnalyzer creates a new DownloadProgressAnalyzer
+func NewDownloadProgressAnalyzer(t *testing.T) *DownloadProgressAnalyzer {
+	return &DownloadProgressAnalyzer{
+		t:       t,
+		Results: map[string]*commands.DownloadProgressEnd{},
+	}
+}
+
+// Process the given DownloadProgress message. If inconsistencies are detected the
+// test will fail.
+func (a *DownloadProgressAnalyzer) Process(progress *commands.DownloadProgress) {
+	if progress == nil {
+		return
+	}
+	if start := progress.GetStart(); start != nil {
+		require.Empty(a.t, a.ongoingDownload, "DownloadProgressStart: started a download without 'completing' the previous one")
+		a.ongoingDownload = start.Url
+	} else if update := progress.GetUpdate(); update != nil {
+		require.NotEmpty(a.t, a.ongoingDownload, "DownloadProgressUpdate: received update, but the download is not yet started...")
+	} else if end := progress.GetEnd(); end != nil {
+		require.NotEmpty(a.t, a.ongoingDownload, "DownloadProgress: received a 'completed' notification but never initiated a download")
+		a.Results[a.ongoingDownload] = end
+		a.ongoingDownload = ""
+	} else {
+		require.FailNow(a.t, "DownloadProgress: received an empty DownloadProgress (without Start, Update or End)")
+	}
+}

rpc/cc/arduino/cli/commands/v1/commands.proto

@@ -238,21 +238,8 @@ message UpdateIndexRequest {
 }
 
 message UpdateIndexResponse {
-  oneof message {
-    // Progress of the platforms index download.
-    DownloadProgress download_progress = 1;
-    // Report of the index update downloads.
-    DownloadResult download_result = 2;
-  }
-}
-
-message DownloadResult {
-  // Index URL.
-  string url = 1;
-  // Download result: true if successful, false if an error occurred.
-  bool successful = 2;
-  // Download error details.
-  string error = 3;
+  // Progress of the package index download.
+  DownloadProgress download_progress = 1;
 }
 
 message UpdateLibrariesIndexRequest {

rpc/cc/arduino/cli/commands/v1/common.go

@@ -18,8 +18,41 @@ package commands
 // DownloadProgressCB is a callback to get updates on download progress
 type DownloadProgressCB func(curr *DownloadProgress)
 
-// DownloadResultCB is a callback to get the result of a download
-type DownloadResultCB func(res *DownloadResult)
+// Start sends a "start" DownloadProgress message to the callback function
+func (d DownloadProgressCB) Start(url, label string) {
+	d(&DownloadProgress{
+		Message: &DownloadProgress_Start{
+			Start: &DownloadProgressStart{
+				Url:   url,
+				Label: label,
+			},
+		},
+	})
+}
+
+// Update sends an "update" DownloadProgress message to the callback function
+func (d DownloadProgressCB) Update(downloaded int64, totalSize int64) {
+	d(&DownloadProgress{
+		Message: &DownloadProgress_Update{
+			Update: &DownloadProgressUpdate{
+				Downloaded: downloaded,
+				TotalSize:  totalSize,
+			},
+		},
+	})
+}
+
+// End sends an "end" DownloadProgress message to the callback function
+func (d DownloadProgressCB) End(success bool, message string) {
+	d(&DownloadProgress{
+		Message: &DownloadProgress_End{
+			End: &DownloadProgressEnd{
+				Success: success,
+				Message: message,
+			},
+		},
+	})
+}
 
 // TaskProgressCB is a callback to receive progress messages
 type TaskProgressCB func(msg *TaskProgress)

rpc/cc/arduino/cli/commands/v1/common.proto

@@ -25,16 +25,33 @@ message Instance {
 }
 
 message DownloadProgress {
+  oneof message {
+    DownloadProgressStart start = 1;
+    DownloadProgressUpdate update = 2;
+    DownloadProgressEnd end = 3;
+  }
+}
+
+message DownloadProgressStart {
   // URL of the download.
   string url = 1;
-  // The file being downloaded.
-  string file = 2;
-  // Total size of the file being downloaded.
-  int64 total_size = 3;
+  // The label to display on the progress bar.
+  string label = 2;
+}
+
+message DownloadProgressUpdate {
   // Size of the downloaded portion of the file.
-  int64 downloaded = 4;
-  // Whether the download is complete.
-  bool completed = 5;
+  int64 downloaded = 1;
+  // Total size of the file being downloaded.
+  int64 total_size = 2;
+}
+
+message DownloadProgressEnd {
+  // True if the download is successful
+  bool success = 1;
+  // Info or error message, depending on the value of 'success'. Some examples:
+  // "File xxx already downloaded" or "Connection timeout"
+  string message = 2;
 }
 
 message TaskProgress {

test/test_core.py

@@ -94,8 +94,10 @@ def test_core_updateindex_url_not_found(run_command, httpserver):
 
     result = run_command(["core", "update-index", f"--additional-urls={url}"])
     assert result.failed
-    lines = [l.strip() for l in result.stderr.splitlines()]
-    assert f"Error updating index: Error downloading index '{url}': Server responded with: 404 NOT FOUND" in lines
+    linesout = [l.strip() for l in result.stdout.splitlines()]
+    assert "Downloading index: test_index.json Server responded with: 404 NOT FOUND" in linesout
+    lineserr = [l.strip() for l in result.stderr.splitlines()]
+    assert "Some indexes could not be updated." in lineserr
 
 
 def test_core_updateindex_internal_server_error(run_command, httpserver):
@@ -107,11 +109,8 @@ def test_core_updateindex_internal_server_error(run_command, httpserver):
 
     result = run_command(["core", "update-index", f"--additional-urls={url}"])
     assert result.failed
-    lines = [l.strip() for l in result.stderr.splitlines()]
-    assert (
-        f"Error updating index: Error downloading index '{url}': Server responded with: 500 INTERNAL SERVER ERROR"
-        in lines
-    )
+    lines = [l.strip() for l in result.stdout.splitlines()]
+    assert "Downloading index: test_index.json Server responded with: 500 INTERNAL SERVER ERROR" in lines
 
 
 def test_core_install_without_updateindex(run_command):

test/test_update.py

@@ -60,8 +60,8 @@ def test_update_with_url_not_found(run_command, httpserver):
 
     res = run_command(["update", f"--additional-urls={url}"])
     assert res.failed
-    lines = [l.strip() for l in res.stderr.splitlines()]
-    assert f"Error updating index: Error downloading index '{url}': Server responded with: 404 NOT FOUND" in lines
+    lines = [l.strip() for l in res.stdout.splitlines()]
+    assert "Downloading index: test_index.json Server responded with: 404 NOT FOUND" in lines
 
 
 def test_update_with_url_internal_server_error(run_command, httpserver):
@@ -73,11 +73,8 @@ def test_update_with_url_internal_server_error(run_command, httpserver):
 
     res = run_command(["update", f"--additional-urls={url}"])
     assert res.failed
-    lines = [l.strip() for l in res.stderr.splitlines()]
-    assert (
-        f"Error updating index: Error downloading index '{url}': Server responded with: 500 INTERNAL SERVER ERROR"
-        in lines
-    )
+    lines = [l.strip() for l in res.stdout.splitlines()]
+    assert "Downloading index: test_index.json Server responded with: 500 INTERNAL SERVER ERROR" in lines
 
 
 def test_update_showing_outdated_using_library_with_invalid_version(run_command, data_dir):