feat(cmd) Add Pluggable InMemory Cache for downloading charts

This feature allows us to use the --use-inmemory-cache flag to
use a chart without downloading it to the helm repository cache,
instead which is downloaded to InMemoryCache

Signed-off-by: Vibhav Bobade <vibhav.bobde@gmail.com>

cmd/helm/install.go

@@ -19,6 +19,8 @@ package main
 import (
 	"fmt"
 	"io"
+	"os"
+	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -151,6 +153,7 @@ func addInstallFlags(f *pflag.FlagSet, client *action.Install, valueOpts *values
 	f.BoolVar(&client.Atomic, "atomic", false, "if set, the installation process deletes the installation on failure. The --wait flag will be set automatically if --atomic is used")
 	f.BoolVar(&client.SkipCRDs, "skip-crds", false, "if set, no CRDs will be installed. By default, CRDs are installed if not already present")
 	f.BoolVar(&client.SubNotes, "render-subchart-notes", false, "if set, render subchart notes along with the parent")
+	f.BoolVar(&client.ReadOnlyFS, "readonly-fs", false, "if set, do not download charts to the HELM_REPOSITORY_CACHE")
 	addValueOptionsFlags(f, valueOpts)
 	addChartPathOptionsFlags(f, &client.ChartPathOptions)
 }
@@ -162,13 +165,13 @@ func runInstall(args []string, client *action.Install, valueOpts *values.Options
 		client.Version = ">0.0.0-0"
 	}
 
-	name, chart, err := client.NameAndChart(args)
+	name, schart, err := client.NameAndChart(args)
 	if err != nil {
 		return nil, err
 	}
 	client.ReleaseName = name
 
-	cp, err := client.ChartPathOptions.LocateChart(chart, settings)
+	cp, err := client.ChartPathOptions.LocateChart(schart, settings)
 	if err != nil {
 		return nil, err
 	}
@@ -181,8 +184,17 @@ func runInstall(args []string, client *action.Install, valueOpts *values.Options
 		return nil, err
 	}
 
-	// Check chart dependencies to make sure all are present in /charts
+	// Check chart dependencies to make sure all are present in the inMemoryCache or in /charts
-	chartRequested, err := loader.Load(cp)
+	var chartRequested *chart.Chart
+	if client.ReadOnlyFS {
+		if _, err = os.Stat(cp); err == nil {
+			chartRequested, err = loader.Load(cp)
+		} else {
+			chartRequested, err = downloader.GetChart(schart, strings.TrimSpace(client.ChartPathOptions.Version))
+		}
+	} else {
+		chartRequested, err = loader.Load(cp)
+	}
 	if err != nil {
 		return nil, err
 	}

cmd/helm/install_test.go

@@ -195,6 +195,12 @@ func TestInstall(t *testing.T) {
 			cmd:    "install aeneas testdata/testcharts/deprecated --namespace default",
 			golden: "output/deprecated-chart.txt",
 		},
+		// Install with non url and in-memory-cache enabled
+		{
+			name:      "install with inMemory cache enabled ",
+			cmd:       "install cached testdata/testcharts/empty --namespace default --use-inmemory-cache",
+			wantError: true,
+		},
 	}
 
 	runTestActionCmd(t, tests)