Merge pull request #175 from priyawadhwa/quiet-flag

Add quiet flag to suppress stderr output

Author: priyawadhwa

README.md

@@ -111,6 +111,10 @@ To order files and packages by size (in descending order) when performing file s
 container-diff analyze remote://gcr.io/gcp-runtimes/multi-modified --type=pip --order
 ```
 
+To suppress output to stderr, add a `-q` or `--quiet` flag.
+```shell
+container-diff analyze file1.tar --type=file --quiet
+```
 
 ## Analysis Result Format
 

cmd/BUILD.bazel

@@ -11,6 +11,7 @@ go_library(
     importpath = "github.com/GoogleCloudPlatform/container-diff/cmd",
     visibility = ["//visibility:public"],
     deps = [
+        "//cmd/util/output:go_default_library",
         "//differs:go_default_library",
         "//pkg/cache:go_default_library",
         "//pkg/util:go_default_library",

cmd/analyze.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/GoogleCloudPlatform/container-diff/cmd/util/output"
 	"github.com/GoogleCloudPlatform/container-diff/differs"
 	pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
 	"github.com/sirupsen/logrus"
@@ -86,7 +87,7 @@ func analyzeImage(imageName string, analyzerArgs []string) error {
 		return fmt.Errorf("Error performing image analysis: %s", err)
 	}
 
-	fmt.Fprintln(os.Stderr, "Retrieving analyses")
+	output.PrintToStdErr("Retrieving analyses")
 	outputResults(analyses)
 
 	if save {
@@ -99,4 +100,5 @@ func analyzeImage(imageName string, analyzerArgs []string) error {
 func init() {
 	RootCmd.AddCommand(analyzeCmd)
 	addSharedFlags(analyzeCmd)
+	output.AddFlags(analyzeCmd)
 }

cmd/diff.go

@@ -22,6 +22,7 @@ import (
 	"os"
 	"sync"
 
+	"github.com/GoogleCloudPlatform/container-diff/cmd/util/output"
 	"github.com/GoogleCloudPlatform/container-diff/differs"
 	pkgutil "github.com/GoogleCloudPlatform/container-diff/pkg/util"
 	"github.com/GoogleCloudPlatform/container-diff/util"
@@ -82,7 +83,7 @@ func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	var wg sync.WaitGroup
 	wg.Add(2)
 
-	fmt.Fprintf(os.Stderr, "Starting diff on images %s and %s, using differs: %s\n", image1Arg, image2Arg, diffArgs)
+	output.PrintToStdErr("Starting diff on images %s and %s, using differs: %s\n", image1Arg, image2Arg, diffArgs)
 
 	imageMap := map[string]*pkgutil.Image{
 		image1Arg: {},
@@ -112,7 +113,7 @@ func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 		defer pkgutil.CleanupImage(*imageMap[image2Arg])
 	}
 
-	fmt.Fprintln(os.Stderr, "Computing diffs")
+	output.PrintToStdErr("Computing diffs")
 	req := differs.DiffRequest{
 		Image1:    *imageMap[image1Arg],
 		Image2:    *imageMap[image2Arg],
@@ -124,7 +125,7 @@ func diffImages(image1Arg, image2Arg string, diffArgs []string) error {
 	outputResults(diffs)
 
 	if filename != "" {
-		fmt.Fprintln(os.Stderr, "Computing filename diffs")
+		output.PrintToStdErr("Computing filename diffs")
 		err := diffFile(imageMap[image1Arg], imageMap[image2Arg])
 		if err != nil {
 			return err
@@ -151,4 +152,5 @@ func init() {
 	diffCmd.Flags().StringVarP(&filename, "filename", "f", "", "Set this flag to the path of a file in both containers to view the diff of the file. Must be used with --types=file flag.")
 	RootCmd.AddCommand(diffCmd)
 	addSharedFlags(diffCmd)
+	output.AddFlags(diffCmd)
 }

cmd/util/output/BUILD.bazel

@@ -0,0 +1,9 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["output.go"],
+    importpath = "github.com/GoogleCloudPlatform/container-diff/cmd/util/output",
+    visibility = ["//visibility:public"],
+    deps = ["//vendor/github.com/spf13/cobra:go_default_library"],
+)

cmd/util/output/output.go

@@ -0,0 +1,37 @@
+/*
+Copyright 2017 Google, Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package output
+
+import (
+	"fmt"
+	"github.com/spf13/cobra"
+	"os"
+)
+
+var quiet bool
+
+// PrintToStdErr prints to stderr if quiet flag isn't enabled
+func PrintToStdErr(output string, vars ...interface{}) {
+	if !quiet {
+		fmt.Fprintf(os.Stderr, output, vars...)
+	}
+}
+
+// AddFlags adds quiet flag to suppress output to stderr
+func AddFlags(cmd *cobra.Command) {
+	cmd.Flags().BoolVarP(&quiet, "quiet", "q", false, "Suppress output to stderr.")
+}

differs/rpm_diff.go

@@ -112,7 +112,7 @@ func rpmDataFromContainer(image pkgutil.Image) (map[string]util.PackageInfo, err
 
 		archive, err := generateNewArchive(imageName)
 		if err != nil {
-			fmt.Println(err.Error())
+			logrus.Errorf(err.Error())
 		}
 		defer os.Remove(archive)
 

pkg/util/BUILD.bazel

@@ -15,6 +15,7 @@ go_library(
     importpath = "github.com/GoogleCloudPlatform/container-diff/pkg/util",
     visibility = ["//visibility:public"],
     deps = [
+        "//cmd/util/output:go_default_library",
         "//pkg/cache:go_default_library",
         "//vendor/github.com/containers/image/docker:go_default_library",
         "//vendor/github.com/containers/image/docker/daemon:go_default_library",

pkg/util/image_prep_utils.go

@@ -20,12 +20,12 @@ import (
 	"archive/tar"
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
 	"strings"
 
+	"github.com/GoogleCloudPlatform/container-diff/cmd/util/output"
 	"github.com/GoogleCloudPlatform/container-diff/pkg/cache"
 	"github.com/containers/image/docker"
 	"github.com/containers/image/manifest"
@@ -100,7 +100,7 @@ type ConfigSchema struct {
 }
 
 func getImage(p Prepper) (Image, error) {
-	fmt.Fprintf(os.Stderr, "Retrieving image %s from source %s\n", p.GetSource(), p.Name())
+	output.PrintToStdErr("Retrieving image %s from source %s\n", p.GetSource(), p.Name())
 	imgPath, err := p.GetFileSystem()
 	if err != nil {
 		return Image{}, err