feat: Add flags to enable CPU and memory profiling

Add capability to profile cli command using
https://go.dev/blog/pprof

Signed-off-by: Evans Mungai <mbuevans@gmail.com>

CONTRIBUTING.md

@@ -276,12 +276,24 @@ Like any good open source project, we use Pull Requests (PRs) to track code chan
       or explicitly request another OWNER do that for them.
     - If the owner of a PR is _not_ listed in `OWNERS`, any core maintainer may merge the PR.
 
-#### Documentation PRs
+### Documentation PRs
 
 Documentation PRs should be made on the docs repo: <https://github.com/helm/helm-www>. Keeping Helm's documentation up to date is highly desirable, and is recommended for all user facing changes. Accurate and helpful documentation is critical for effectively communicating Helm's behavior to a wide audience.
 
 Small, ad-hoc changes/PRs to Helm which introduce user facing changes, which would benefit from documentation changes, should apply the `docs needed` label. Larger changes associated with a HIP should track docs via that HIP. The `docs needed` label doesn't block PRs, and maintainers/PR reviewers should apply discretion judging in whether the `docs needed` label should be applied.
 
+### Testing PRs
+
+During development, you need to add automated tests where possible. There are a few `make test*` targets that you can use to execute your unit or integration tests. If your contribution requires profiling to check memory and/or CPU usage, you can use `--cpuprofile` and/or `--memprofile` global cli flags to run collect runtime profiling data for analysis. You can use Golang's [pprof](https://github.com/google/pprof/blob/main/doc/README.md) tool to inspect the profiling data.
+
+Example invocation that collects profiling data
+```
+helm show all bitnami/nginx --memprofile mem.prof --cpuprofile cpu.prof
+
+# Visualize graphs. You need to have installed graphviz in you system
+go tool pprof -http=":8000" cpu.prof
+```
+
 ## The Triager
 
 Each week, one of the core maintainers will serve as the designated "triager" starting after the

cmd/helm/profiling.go

@@ -0,0 +1,76 @@
+// Profile CPU and memory usage of Helm commands
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+var (
+	cpuProfileFile *os.File
+)
+
+// startProfiling starts profiling CPU usage
+func startProfiling(cpuprofile string) error {
+	if cpuprofile != "" {
+		var err error
+		cpuProfileFile, err = os.Create(cpuprofile)
+		if err != nil {
+			return fmt.Errorf("could not create CPU profile: %w", err)
+		}
+		if err := pprof.StartCPUProfile(cpuProfileFile); err != nil {
+			cpuProfileFile.Close()
+			cpuProfileFile = nil
+			return fmt.Errorf("could not start CPU profile: %w", err)
+		}
+	}
+	return nil
+}
+
+// stopProfiling stops profiling CPU and memory usage and writes the results to
+// the files specified by --cpuprofile and --memprofile flags respectively.
+func stopProfiling(memprofile string) error {
+	errs := []string{}
+
+	// Stop CPU profiling if it was started
+	if cpuProfileFile != nil {
+		pprof.StopCPUProfile()
+		err := cpuProfileFile.Close()
+		if err != nil {
+			errs = append(errs, err.Error())
+		}
+		cpuProfileFile = nil
+	}
+
+	if memprofile != "" {
+		f, err := os.Create(memprofile)
+		if err != nil {
+			errs = append(errs, err.Error())
+		}
+		defer f.Close()
+
+		runtime.GC() // get up-to-date statistics
+		if err := pprof.WriteHeapProfile(f); err != nil {
+			errs = append(errs, err.Error())
+		}
+	}
+
+	if len(errs) > 0 {
+		return fmt.Errorf("errors while stopping profiling: [%s]", strings.Join(errs, ", "))
+	}
+
+	return nil
+}
+
+// addProfilingFlags adds the --cpuprofile and --memprofile flags to the given command.
+func addProfilingFlags(cmd *cobra.Command) {
+	// Persistent flags to make available to subcommands
+	cmd.PersistentFlags().String("cpuprofile", "", "File path to write cpu profiling data")
+	cmd.PersistentFlags().String("memprofile", "", "File path to write memory profiling data")
+}

cmd/helm/root.go

@@ -95,6 +95,26 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 		Short:        "The Helm package manager for Kubernetes.",
 		Long:         globalUsage,
 		SilenceUsage: true,
+		PersistentPreRun: func(cmd *cobra.Command, args []string) {
+			cpuprof, err := cmd.Flags().GetString("cpuprofile")
+			if err != nil {
+				log.Printf("Warning: Failed to get cpuprofile flag: %v", err)
+			}
+
+			if err := startProfiling(cpuprof); err != nil {
+				log.Printf("Warning: Failed to start profiling: %v", err)
+			}
+		},
+		PersistentPostRun: func(cmd *cobra.Command, args []string) {
+			memprof, err := cmd.Flags().GetString("memprofile")
+			if err != nil {
+				log.Printf("Warning: Failed to get memprofile flag: %v", err)
+			}
+
+			if err := stopProfiling(memprof); err != nil {
+				log.Printf("Warning: Failed to stop profiling: %v", err)
+			}
+		},
 	}
 	flags := cmd.PersistentFlags()
 
@@ -206,6 +226,9 @@ func newRootCmd(actionConfig *action.Configuration, out io.Writer, args []string
 	// Check for expired repositories
 	checkForExpiredRepos(settings.RepositoryConfig)
 
+	// CPU and memory profiling flags that are available to all commands
+	addProfilingFlags(cmd)
+
 	return cmd, nil
 }