Add flag to exit with 1 if no results found

The `--fail-if-no-results-found` flag exit with status code 1 if no
search results found during `helm search repo` and `helm search hub`
commands.  This is useful for automation scripts.

closes #7197

Signed-off-by: Baiju Muthukadan <baiju.m.mail@gmail.com>

cmd/helm/search_hub.go

@@ -19,6 +19,7 @@ package main
 import (
 	"fmt"
 	"io"
+	"os"
 	"strings"
 
 	"github.com/gosuri/uitable"
@@ -54,6 +55,7 @@ type searchHubOptions struct {
 	maxColWidth    uint
 	outputFormat   output.Format
 	listRepoURL    bool
+	noResultsFail  bool
 }
 
 func newSearchHubCmd(out io.Writer) *cobra.Command {
@@ -72,7 +74,7 @@ func newSearchHubCmd(out io.Writer) *cobra.Command {
 	f.StringVar(&o.searchEndpoint, "endpoint", "https://hub.helm.sh", "Hub instance to query for charts")
 	f.UintVar(&o.maxColWidth, "max-col-width", 50, "maximum column width for output table")
 	f.BoolVar(&o.listRepoURL, "list-repo-url", false, "print charts repository URL")
-
+	f.BoolVarP(&o.noResultsFail, "fail-if-no-results-found", "f", false, "exit with status code 1 if no results found")
 	bindOutputFlag(cmd, &o.outputFormat)
 
 	return cmd
@@ -91,7 +93,7 @@ func (o *searchHubOptions) run(out io.Writer, args []string) error {
 		return fmt.Errorf("unable to perform search against %q", o.searchEndpoint)
 	}
 
-	return o.outputFormat.Write(out, newHubSearchWriter(results, o.searchEndpoint, o.maxColWidth, o.listRepoURL))
+	return o.outputFormat.Write(out, newHubSearchWriter(results, o.searchEndpoint, o.maxColWidth, o.noResultsFail, o.listRepoURL))
 }
 
 type hubChartRepo struct {
@@ -108,12 +110,13 @@ type hubChartElement struct {
 }
 
 type hubSearchWriter struct {
-	elements    []hubChartElement
-	columnWidth uint
-	listRepoURL bool
+	elements      []hubChartElement
+	columnWidth   uint
+	listRepoURL   bool
+	noResultsFail bool
 }
 
-func newHubSearchWriter(results []monocular.SearchResult, endpoint string, columnWidth uint, listRepoURL bool) *hubSearchWriter {
+func newHubSearchWriter(results []monocular.SearchResult, endpoint string, columnWidth uint, listRepoURL, noResultsFail bool) *hubSearchWriter {
 	var elements []hubChartElement
 	for _, r := range results {
 		// Backwards compatibility for Monocular
@@ -126,7 +129,7 @@ func newHubSearchWriter(results []monocular.SearchResult, endpoint string, colum
 
 		elements = append(elements, hubChartElement{url, r.Relationships.LatestChartVersion.Data.Version, r.Relationships.LatestChartVersion.Data.AppVersion, r.Attributes.Description, hubChartRepo{URL: r.Attributes.Repo.URL, Name: r.Attributes.Repo.Name}})
 	}
-	return &hubSearchWriter{elements, columnWidth, listRepoURL}
+	return &hubSearchWriter{elements, columnWidth, listRepoURL, noResultsFail}
 }
 
 func (h *hubSearchWriter) WriteTable(out io.Writer) error {
@@ -135,6 +138,9 @@ func (h *hubSearchWriter) WriteTable(out io.Writer) error {
 		if err != nil {
 			return fmt.Errorf("unable to write results: %s", err)
 		}
+		if h.noResultsFail {
+			os.Exit(1)
+		}
 		return nil
 	}
 	table := uitable.New()

cmd/helm/search_repo.go

@@ -64,14 +64,15 @@ Repositories are managed with 'helm repo' commands.
 const searchMaxScore = 25
 
 type searchRepoOptions struct {
-	versions     bool
-	regexp       bool
-	devel        bool
-	version      string
-	maxColWidth  uint
-	repoFile     string
-	repoCacheDir string
-	outputFormat output.Format
+	versions      bool
+	regexp        bool
+	devel         bool
+	version       string
+	maxColWidth   uint
+	repoFile      string
+	repoCacheDir  string
+	outputFormat  output.Format
+	noResultsFail bool
 }
 
 func newSearchRepoCmd(out io.Writer) *cobra.Command {
@@ -94,6 +95,7 @@ func newSearchRepoCmd(out io.Writer) *cobra.Command {
 	f.BoolVar(&o.devel, "devel", false, "use development versions (alpha, beta, and release candidate releases), too. Equivalent to version '>0.0.0-0'. If --version is set, this is ignored")
 	f.StringVar(&o.version, "version", "", "search using semantic versioning constraints on repositories you have added")
 	f.UintVar(&o.maxColWidth, "max-col-width", 50, "maximum column width for output table")
+	f.BoolVarP(&o.noResultsFail, "fail-if-no-results-found", "f", false, "exit with status code 1 if no results found")
 	bindOutputFlag(cmd, &o.outputFormat)
 
 	return cmd
@@ -124,7 +126,7 @@ func (o *searchRepoOptions) run(out io.Writer, args []string) error {
 		return err
 	}
 
-	return o.outputFormat.Write(out, &repoSearchWriter{data, o.maxColWidth})
+	return o.outputFormat.Write(out, &repoSearchWriter{data, o.maxColWidth, o.noResultsFail})
 }
 
 func (o *searchRepoOptions) setupSearchedVersion() {
@@ -205,8 +207,9 @@ type repoChartElement struct {
 }
 
 type repoSearchWriter struct {
-	results     []*search.Result
-	columnWidth uint
+	results       []*search.Result
+	columnWidth   uint
+	noResultsFail bool
 }
 
 func (r *repoSearchWriter) WriteTable(out io.Writer) error {
@@ -215,6 +218,9 @@ func (r *repoSearchWriter) WriteTable(out io.Writer) error {
 		if err != nil {
 			return fmt.Errorf("unable to write results: %s", err)
 		}
+		if r.noResultsFail {
+			os.Exit(1)
+		}
 		return nil
 	}
 	table := uitable.New()