pkg/cwhub: download data assets to temporary files to avoid partial fetch (#2879)

pkg/cwhub/dataset.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"net/http"
 	"os"
+	"path/filepath"
 	"time"
 
 	"github.com/sirupsen/logrus"
@@ -31,19 +32,32 @@ func downloadFile(url string, destPath string) error {
 		return fmt.Errorf("bad http code %d for %s", resp.StatusCode, url)
 	}
 
-	file, err := os.Create(destPath)
+	tmpFile, err := os.CreateTemp(filepath.Dir(destPath), filepath.Base(destPath)+".*.tmp")
 	if err != nil {
 		return err
 	}
-	defer file.Close()
+
+	tmpFileName := tmpFile.Name()
+	defer func() {
+		tmpFile.Close()
+		os.Remove(tmpFileName)
+	}()
 
 	// avoid reading the whole file in memory
-	_, err = io.Copy(file, resp.Body)
+	_, err = io.Copy(tmpFile, resp.Body)
 	if err != nil {
 		return err
 	}
 
-	if err = file.Sync(); err != nil {
+	if err = tmpFile.Sync(); err != nil {
+		return err
+	}
+
+	if err = tmpFile.Close(); err != nil {
+		return err
+	}
+
+	if err = os.Rename(tmpFileName, destPath); err != nil {
 		return err
 	}
 

pkg/cwhub/dataset_test.go

@@ -16,7 +16,7 @@ func TestDownloadFile(t *testing.T) {
 	httpmock.Activate()
 	defer httpmock.DeactivateAndReset()
 
-	//OK
+	// OK
 	httpmock.RegisterResponder(
 		"GET",
 		"https://example.com/xx",
@@ -36,15 +36,15 @@ func TestDownloadFile(t *testing.T) {
 	assert.Equal(t, "example content oneoneone", string(content))
 	require.NoError(t, err)
 
-	//bad uri
+	// bad uri
 	err = downloadFile("https://zz.com", examplePath)
 	require.Error(t, err)
 
-	//404
+	// 404
 	err = downloadFile("https://example.com/x", examplePath)
 	require.Error(t, err)
 
-	//bad target
+	// bad target
 	err = downloadFile("https://example.com/xx", "")
 	require.Error(t, err)
 }

pkg/cwhub/errors.go

@@ -6,7 +6,7 @@ import (
 )
 
 var (
-	// ErrNilRemoteHub is returned when the remote hub configuration is not provided to the NewHub constructor.
+	// ErrNilRemoteHub is returned when trying to download with a local-only configuration.
 	ErrNilRemoteHub = errors.New("remote hub configuration is not provided. Please report this issue to the developers")
 )
 

pkg/cwhub/hub.go

@@ -3,6 +3,7 @@ package cwhub
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"os"
@@ -34,7 +35,7 @@ func (h *Hub) GetDataDir() string {
 // All download operations (including updateIndex) return ErrNilRemoteHub if the remote configuration is not set.
 func NewHub(local *csconfig.LocalHubCfg, remote *RemoteHubCfg, updateIndex bool, logger *logrus.Logger) (*Hub, error) {
 	if local == nil {
-		return nil, fmt.Errorf("no hub configuration found")
+		return nil, errors.New("no hub configuration found")
 	}
 
 	if logger == nil {

pkg/cwhub/sync.go

@@ -77,9 +77,9 @@ func (h *Hub) getItemFileInfo(path string, logger *logrus.Logger) (*itemFileInfo
 	if strings.HasPrefix(path, hubDir) {
 		logger.Tracef("in hub dir")
 
-		//.../hub/parsers/s00-raw/crowdsec/skip-pretag.yaml
-		//.../hub/scenarios/crowdsec/ssh_bf.yaml
-		//.../hub/profiles/crowdsec/linux.yaml
+		// .../hub/parsers/s00-raw/crowdsec/skip-pretag.yaml
+		// .../hub/scenarios/crowdsec/ssh_bf.yaml
+		// .../hub/profiles/crowdsec/linux.yaml
 		if len(subs) < 4 {
 			return nil, fmt.Errorf("path is too short: %s (%d)", path, len(subs))
 		}
@@ -93,13 +93,14 @@ func (h *Hub) getItemFileInfo(path string, logger *logrus.Logger) (*itemFileInfo
 		}
 	} else if strings.HasPrefix(path, installDir) { // we're in install /etc/crowdsec/<type>/...
 		logger.Tracef("in install dir")
+
 		if len(subs) < 3 {
 			return nil, fmt.Errorf("path is too short: %s (%d)", path, len(subs))
 		}
-		///.../config/parser/stage/file.yaml
-		///.../config/postoverflow/stage/file.yaml
-		///.../config/scenarios/scenar.yaml
-		///.../config/collections/linux.yaml //file is empty
+		// .../config/parser/stage/file.yaml
+		// .../config/postoverflow/stage/file.yaml
+		// .../config/scenarios/scenar.yaml
+		// .../config/collections/linux.yaml //file is empty
 		ret = &itemFileInfo{
 			inhub:   false,
 			fname:   subs[len(subs)-1],