Merge pull request #173 from priyawadhwa/cleanup-output

Add --format flag to customize output

Author: priyawadhwa

README.md

@@ -239,6 +239,42 @@ type MultiVersionInfo struct {
 }
 ```
 
+## User Customized Output
+Users can customize the format of the output of diffs with the`--format` flag. The flag takes a Go template string, which specifies the format the diff should be output in. This template string uses the structs described above, depending on the differ used, to format output.  The default template strings container-diff uses can be found [here](https://github.com/GoogleCloudPlatform/container-diff/blob/master/util/template_utils.go).
+
+An example using the pip package analyzer is shown below, in which only package names are printed (some are repeated because of version differences).
+
+```shell
+$ container-diff analyze gcr.io/google-appengine/python:latest --type=pip --format='
+-----{{.AnalyzeType}}-----
+Packages found in {{.Image}}:{{if not .Analysis}} None{{else}}
+{{range .Analysis}}{{"\n"}}{{.Name}}{{end}}
+{{end}}
+'
+Retrieving image gcr.io/google-appengine/python:latest from source Cloud Registry
+Retrieving analyses
+
+-----Pip-----
+Packages found in gcr.io/google-appengine/python:latest:
+
+chardet
+colorama
+html5lib
+mercurial
+pip
+pip
+pip
+requests
+setuptools
+setuptools
+setuptools
+six
+urllib3
+virtualenv
+wheel
+wheel
+```
+
 ## Known issues
 
 To run container-diff using image IDs, docker must be installed.
@@ -422,7 +458,7 @@ If using existing package tools, you should create the appropriate structs (e.g.
 ```go
 type Result interface {
 	OutputStruct() interface{}
-	OutputText(resultType string) error
+	OutputText(resultType string, format string) error
 }
 ```
 

cmd/root.go

@@ -41,6 +41,7 @@ var types diffTypes
 var noCache bool
 
 var LogLevel string
+var format string
 
 type validatefxn func(args []string) error
 
@@ -84,7 +85,7 @@ func outputResults(resultMap map[string]util.Result) {
 		if json {
 			results[i] = result.OutputStruct()
 		} else {
-			err := result.OutputText(analyzerType)
+			err := result.OutputText(analyzerType, format)
 			if err != nil {
 				logrus.Error(err)
 			}
@@ -178,6 +179,7 @@ func cacheDir() (string, error) {
 
 func init() {
 	RootCmd.PersistentFlags().StringVarP(&LogLevel, "verbosity", "v", "warning", "This flag controls the verbosity of container-diff.")
+	RootCmd.PersistentFlags().StringVarP(&format, "format", "", "", "Format to output diff in.")
 	pflag.CommandLine.AddGoFlagSet(goflag.CommandLine)
 }
 

util/analyze_output_utils.go

@@ -26,7 +26,7 @@ import (
 
 type Result interface {
 	OutputStruct() interface{}
-	OutputText(resultType string) error
+	OutputText(resultType string, format string) error
 }
 
 type AnalyzeResult struct {
@@ -41,15 +41,15 @@ func (r ListAnalyzeResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r ListAnalyzeResult) OutputText(resultType string) error {
+func (r ListAnalyzeResult) OutputText(resultType string, format string) error {
 	analysis, valid := r.Analysis.([]string)
 	if !valid {
 		logrus.Error("Unexpected structure of Analysis.  Should be of type []string")
 		return fmt.Errorf("Could not output %s analysis result", r.AnalyzeType)
 	}
 	r.Analysis = analysis
+	return TemplateOutputFromFormat(r, "ListAnalyze", format)
 
-	return TemplateOutput(r, "ListAnalyze")
 }
 
 type MultiVersionPackageAnalyzeResult AnalyzeResult
@@ -73,7 +73,7 @@ func (r MultiVersionPackageAnalyzeResult) OutputStruct() interface{} {
 	return output
 }
 
-func (r MultiVersionPackageAnalyzeResult) OutputText(resultType string) error {
+func (r MultiVersionPackageAnalyzeResult) OutputText(resultType string, format string) error {
 	analysis, valid := r.Analysis.(map[string]map[string]PackageInfo)
 	if !valid {
 		logrus.Error("Unexpected structure of Analysis.  Should be of type map[string]map[string]PackageInfo")
@@ -91,7 +91,7 @@ func (r MultiVersionPackageAnalyzeResult) OutputText(resultType string) error {
 		AnalyzeType: r.AnalyzeType,
 		Analysis:    strAnalysis,
 	}
-	return TemplateOutput(strResult, "MultiVersionPackageAnalyze")
+	return TemplateOutputFromFormat(strResult, "MultiVersionPackageAnalyze", format)
 }
 
 type SingleVersionPackageAnalyzeResult AnalyzeResult
@@ -115,7 +115,7 @@ func (r SingleVersionPackageAnalyzeResult) OutputStruct() interface{} {
 	return output
 }
 
-func (r SingleVersionPackageAnalyzeResult) OutputText(diffType string) error {
+func (r SingleVersionPackageAnalyzeResult) OutputText(diffType string, format string) error {
 	analysis, valid := r.Analysis.(map[string]PackageInfo)
 	if !valid {
 		logrus.Error("Unexpected structure of Analysis.  Should be of type map[string]PackageInfo")
@@ -133,7 +133,7 @@ func (r SingleVersionPackageAnalyzeResult) OutputText(diffType string) error {
 		AnalyzeType: r.AnalyzeType,
 		Analysis:    strAnalysis,
 	}
-	return TemplateOutput(strResult, "SingleVersionPackageAnalyze")
+	return TemplateOutputFromFormat(strResult, "SingleVersionPackageAnalyze", format)
 }
 
 type PackageOutput struct {
@@ -191,7 +191,7 @@ func (r FileAnalyzeResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r FileAnalyzeResult) OutputText(analyzeType string) error {
+func (r FileAnalyzeResult) OutputText(analyzeType string, format string) error {
 	analysis, valid := r.Analysis.([]util.DirectoryEntry)
 	if !valid {
 		logrus.Error("Unexpected structure of Analysis.  Should be of type []DirectoryEntry")
@@ -214,5 +214,5 @@ func (r FileAnalyzeResult) OutputText(analyzeType string) error {
 		AnalyzeType: r.AnalyzeType,
 		Analysis:    strAnalysis,
 	}
-	return TemplateOutput(strResult, "FileAnalyze")
+	return TemplateOutputFromFormat(strResult, "FileAnalyze", format)
 }

util/diff_output_utils.go

@@ -52,7 +52,7 @@ func (r MultiVersionPackageDiffResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r MultiVersionPackageDiffResult) OutputText(diffType string) error {
+func (r MultiVersionPackageDiffResult) OutputText(diffType string, format string) error {
 	diff, valid := r.Diff.(MultiVersionPackageDiff)
 	if !valid {
 		logrus.Error("Unexpected structure of Diff.  Should follow the MultiVersionPackageDiff struct")
@@ -84,7 +84,7 @@ func (r MultiVersionPackageDiffResult) OutputText(diffType string) error {
 			InfoDiff:  strInfoDiff,
 		},
 	}
-	return TemplateOutput(strResult, "MultiVersionPackageDiff")
+	return TemplateOutputFromFormat(strResult, "MultiVersionPackageDiff", format)
 }
 
 func getMultiVersionInfoDiffOutput(infoDiff []MultiVersionInfo) []MultiVersionInfo {
@@ -118,7 +118,7 @@ func (r SingleVersionPackageDiffResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r SingleVersionPackageDiffResult) OutputText(diffType string) error {
+func (r SingleVersionPackageDiffResult) OutputText(diffType string, format string) error {
 	diff, valid := r.Diff.(PackageDiff)
 	if !valid {
 		logrus.Error("Unexpected structure of Diff.  Should follow the PackageDiff struct")
@@ -150,7 +150,7 @@ func (r SingleVersionPackageDiffResult) OutputText(diffType string) error {
 			InfoDiff:  strInfoDiff,
 		},
 	}
-	return TemplateOutput(strResult, "SingleVersionPackageDiff")
+	return TemplateOutputFromFormat(strResult, "SingleVersionPackageDiff", format)
 }
 
 func getSingleVersionInfoDiffOutput(infoDiff []Info) []Info {
@@ -168,8 +168,8 @@ func (r HistDiffResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r HistDiffResult) OutputText(diffType string) error {
-	return TemplateOutput(r, "HistDiff")
+func (r HistDiffResult) OutputText(diffType string, format string) error {
+	return TemplateOutputFromFormat(r, "HistDiff", format)
 }
 
 type DirDiffResult DiffResult
@@ -185,7 +185,7 @@ func (r DirDiffResult) OutputStruct() interface{} {
 	return r
 }
 
-func (r DirDiffResult) OutputText(diffType string) error {
+func (r DirDiffResult) OutputText(diffType string, format string) error {
 	diff, valid := r.Diff.(DirDiff)
 	if !valid {
 		logrus.Error("Unexpected structure of Diff.  Should follow the DirDiff struct")
@@ -218,5 +218,5 @@ func (r DirDiffResult) OutputText(diffType string) error {
 			Mods: strMods,
 		},
 	}
-	return TemplateOutput(strResult, "DirDiff")
+	return TemplateOutputFromFormat(strResult, "DirDiff", format)
 }

util/format_utils.go

@@ -79,3 +79,23 @@ func TemplateOutput(diff interface{}, templateType string) error {
 	w.Flush()
 	return nil
 }
+
+func TemplateOutputFromFormat(diff interface{}, templateType string, format string) error {
+	if format == "" {
+		return TemplateOutput(diff, templateType)
+	}
+	funcs := template.FuncMap{"join": strings.Join}
+	tmpl, err := template.New("tmpl").Funcs(funcs).Parse(format)
+	if err != nil {
+		logrus.Warningf("User specified format resulted in error, printing default output.")
+		logrus.Error(err)
+		return TemplateOutput(diff, templateType)
+	}
+	w := tabwriter.NewWriter(os.Stdout, 8, 8, 8, ' ', 0)
+	err = tmpl.Execute(w, diff)
+	if err != nil {
+		return err
+	}
+	w.Flush()
+	return nil
+}