cache: allow ellipse style entries for MINIO_CACHE_DRIVES (#6088)

Fixes #5863

cmd/disk-cache-config.go

@@ -19,6 +19,9 @@ package cmd
 import (
 	"encoding/json"
 	"path/filepath"
+	"strings"
+
+	"github.com/minio/minio/pkg/ellipses"
 )
 
 // CacheConfig represents cache config settings
@@ -52,12 +55,42 @@ func (cfg *CacheConfig) UnmarshalJSON(data []byte) (err error) {
 
 // Parses given cacheDrivesEnv and returns a list of cache drives.
 func parseCacheDrives(drives []string) ([]string, error) {
+	if len(drives) == 0 {
+		return drives, nil
+	}
+	var endpoints []string
 	for _, d := range drives {
+		if ellipses.HasEllipses(d) {
+			s, err := parseCacheDrivePaths(d)
+			if err != nil {
+				return nil, err
+			}
+			endpoints = append(endpoints, s...)
+		} else {
+			endpoints = append(endpoints, d)
+		}
+	}
+
+	for _, d := range endpoints {
 		if !filepath.IsAbs(d) {
 			return nil, uiErrInvalidCacheDrivesValue(nil).Msg("cache dir should be absolute path: %s", d)
 		}
 	}
-	return drives, nil
+	return endpoints, nil
+}
+
+// Parses all arguments and returns a slice of drive paths following the ellipses pattern.
+func parseCacheDrivePaths(arg string) (ep []string, err error) {
+	patterns, perr := ellipses.FindEllipsesPatterns(arg)
+	if perr != nil {
+		return []string{}, uiErrInvalidCacheDrivesValue(nil).Msg(perr.Error())
+	}
+
+	for _, lbls := range patterns.Expand() {
+		ep = append(ep, strings.Join(lbls, ""))
+	}
+
+	return ep, nil
 }
 
 // Parses given cacheExcludesEnv and returns a list of cache exclude patterns.