Add retries during source url download (#21)

plugin/harness/execer.go

@@ -127,29 +127,27 @@ func (e *Execer) Exec(ctx context.Context) error {
 			return nil
 		}
 
-		// else if the plugin is a Bash script
-
-		// determine the default script path
-		script := out.Run.Bash.Path
-		shell := "/bin/bash"
-		path := filepath.Join(e.Source, script)
-
-		slog.Debug("execute", slog.String("file", script))
-
+		var path, shell string
 		// if the bash shell does not exist fallback
 		// to posix shell.
 		switch runtime.GOOS {
 		case "windows":
 			// TODO we may want to disable profile and interactive mode
 			// when executing powershell scripts -noprofile -noninteractive
 			shell = "powershell"
+			path = filepath.Join(e.Source, out.Run.Pwsh.Path)
+
 		case "linux", "darwin":
+			shell = "bash"
+			path = filepath.Join(e.Source, out.Run.Bash.Path)
+
 			// fallback to the posix shell if bash
 			// is not available on the host.
 			if _, err := exec.LookPath("bash"); err != nil {
-				shell = "/bin/sh"
+				shell = "sh"
 			}
 		}
+		slog.Debug("execute", slog.String("file", path))
 
 		// execute the binary
 		cmd := exec.Command(shell, path)

plugin/internal/file/file.go

@@ -13,6 +13,7 @@ import (
 	"github.com/drone/plugin/cache"
 	"github.com/klauspost/compress/zstd"
 	"github.com/pkg/errors"
+	"golang.org/x/exp/slog"
 )
 
 const (
@@ -24,7 +25,7 @@ func Download(url string) (string, error) {
 	binPath := filepath.Join(key, "step.exe")
 
 	downloadFn := func() error {
-		if err := download(url, binPath); err != nil {
+		if err := downloadWithRetries(url, binPath); err != nil {
 			return errors.Wrap(err, fmt.Sprintf("url: %s", url))
 		}
 		return nil
@@ -36,6 +37,18 @@ func Download(url string) (string, error) {
 	return binPath, nil
 }
 
+func downloadWithRetries(url, path string) error {
+	var err error
+	for i := 0; i < 3; i++ {
+		if err = download(url, path); err == nil {
+			return nil
+		}
+		slog.Error("failed to download url, retrying", slog.String("url", url), "error", err)
+		time.Sleep(1 * time.Second)
+	}
+	return err
+}
+
 // download method downloads a source & writes it to a file.
 // If file is compressed, it also decompresses the file on the basis of
 // file extension in url. Currently it supports zstd format.