cleanup error handling

Author: nkubala

cmd/analyze.go

@@ -17,7 +17,6 @@ limitations under the License.
 package cmd
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -34,10 +33,10 @@ var analyzeCmd = &cobra.Command{
 	Long:  `Analyzes an image using the specifed analyzers as indicated via flags (see documentation for available ones).`,
 	Args: func(cmd *cobra.Command, args []string) error {
 		if err := validateArgs(args, checkAnalyzeArgNum); err != nil {
-			return errors.New(err.Error())
+			return err
 		}
 		if err := checkIfValidAnalyzer(types); err != nil {
-			return errors.New(err.Error())
+			return err
 		}
 		return nil
 	},
@@ -51,21 +50,20 @@ var analyzeCmd = &cobra.Command{
 
 func checkAnalyzeArgNum(args []string) error {
 	if len(args) != 1 {
-		return errors.New("'analyze' requires one image as an argument: container analyze [image]")
+		return fmt.Errorf("'analyze' requires one image as an argument: container-diff analyze [image]")
 	}
 	return nil
 }
 
 func analyzeImage(imageArg string, analyzerArgs []string) error {
 	analyzeTypes, err := differs.GetAnalyzers(analyzerArgs)
 	if err != nil {
-		glog.Error(err.Error())
-		return errors.New("Could not perform image analysis")
+		return err
 	}
 
 	cli, err := NewClient()
 	if err != nil {
-		return fmt.Errorf("Error getting docker client for differ: %s", err)
+		return fmt.Errorf("Error getting docker client: %s", err)
 	}
 	defer cli.Close()
 	ip := pkgutil.ImagePrepper{
@@ -78,15 +76,13 @@ func analyzeImage(imageArg string, analyzerArgs []string) error {
 		defer pkgutil.CleanupImage(image)
 	}
 	if err != nil {
-		glog.Error(err.Error())
-		return errors.New("Could not perform image analysis")
+		return fmt.Errorf("Error processing image: %s", err)
 	}
 
 	req := differs.SingleRequest{image, analyzeTypes}
 	analyses, err := req.GetAnalysis()
 	if err != nil {
-		glog.Error(err.Error())
-		return errors.New("Could not perform image analysis")
+		return fmt.Errorf("Error performing image analysis: %s", err)
 	}
 
 	glog.Info("Retrieving analyses")

cmd/diff.go

@@ -17,7 +17,6 @@ limitations under the License.
 package cmd
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -35,10 +34,10 @@ var diffCmd = &cobra.Command{
 	Long:  `Compares two images using the specifed analyzers as indicated via flags (see documentation for available ones).`,
 	Args: func(cmd *cobra.Command, args []string) error {
 		if err := validateArgs(args, checkDiffArgNum); err != nil {
-			return errors.New(err.Error())
+			return err
 		}
 		if err := checkIfValidAnalyzer(types); err != nil {
-			return errors.New(err.Error())
+			return err
 		}
 		return nil
 	},
@@ -52,21 +51,20 @@ var diffCmd = &cobra.Command{
 
 func checkDiffArgNum(args []string) error {
 	if len(args) != 2 {
-		return errors.New("'diff' requires two images as arguments: container diff [image1] [image2]")
+		return fmt.Errorf("'diff' requires two images as arguments: container-diff diff [image1] [image2]")
 	}
 	return nil
 }
 
 func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	diffTypes, err := differs.GetAnalyzers(diffArgs)
 	if err != nil {
-		glog.Error(err.Error())
-		return errors.New("Could not perform image diff")
+		return err
 	}
 
 	cli, err := NewClient()
 	if err != nil {
-		return fmt.Errorf("Error getting docker client for differ: %s", err)
+		return err
 	}
 	defer cli.Close()
 	var wg sync.WaitGroup
@@ -102,8 +100,7 @@ func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	req := differs.DiffRequest{*imageMap[image1Arg], *imageMap[image2Arg], diffTypes}
 	diffs, err := req.GetDiff()
 	if err != nil {
-		glog.Error(err.Error())
-		return errors.New("Could not perform image diff")
+		return fmt.Errorf("Could not retrieve diff: %s", err)
 	}
 	glog.Info("Retrieving diffs")
 	outputResults(diffs)

cmd/root.go

@@ -27,7 +27,6 @@ import (
 	"github.com/GoogleCloudPlatform/container-diff/util"
 	"github.com/docker/docker/client"
 	"github.com/golang/glog"
-	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 )
@@ -98,9 +97,7 @@ func checkIfValidAnalyzer(flagtypes string) error {
 	analyzers := strings.Split(flagtypes, ",")
 	for _, name := range analyzers {
 		if _, exists := differs.Analyzers[name]; !exists {
-			errMessage := fmt.Sprintf("Argument %s is not a valid analyzer\n", name)
-			glog.Errorf(errMessage)
-			return errors.New(errMessage)
+			return fmt.Errorf("Argument %s is not a valid analyzer", name)
 		}
 	}
 	return nil

differs/differs.go

@@ -17,7 +17,6 @@ limitations under the License.
 package differs
 
 import (
-	"errors"
 	"fmt"
 
 	pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
@@ -98,16 +97,17 @@ func (req SingleRequest) GetAnalysis() (map[string]util.Result, error) {
 	return results, err
 }
 
-func GetAnalyzers(analyzeNames []string) (analyzeFuncs []Analyzer, err error) {
+func GetAnalyzers(analyzeNames []string) ([]Analyzer, error) {
+	var analyzeFuncs []Analyzer
 	for _, name := range analyzeNames {
 		if a, exists := Analyzers[name]; exists {
 			analyzeFuncs = append(analyzeFuncs, a)
 		} else {
-			glog.Errorf("Unknown analyzer/differ specified", name)
+			return nil, fmt.Errorf("Unknown analyzer/differ specified: %s", name)
 		}
 	}
 	if len(analyzeFuncs) == 0 {
-		err = errors.New("No known analyzers/differs specified")
+		return nil, fmt.Errorf("No known analyzers/differs specified")
 	}
-	return
+	return analyzeFuncs, nil
 }