fix!: support multiple config files in oras cp (oras-project#847)

Signed-off-by: Billy Zha <jinzha1@microsoft.com>

cmd/oras/internal/option/remote.go

@@ -98,10 +98,7 @@ func (opts *Remote) ApplyFlagsWithPrefix(fs *pflag.FlagSet, prefix, description
 	fs.BoolVarP(&opts.PlainHTTP, flagPrefix+"plain-http", "", false, "allow insecure connections to "+notePrefix+"registry without SSL check")
 	fs.StringVarP(&opts.CACertFilePath, flagPrefix+"ca-file", "", "", "server certificate authority file for the remote "+notePrefix+"registry")
 	fs.StringArrayVarP(&opts.resolveFlag, flagPrefix+"resolve", "", nil, "customized DNS for "+notePrefix+"registry, formatted in `host:port:address[:address_port]`")
-
-	if fs.Lookup("registry-config") == nil {
-		fs.StringArrayVarP(&opts.Configs, "registry-config", "", nil, "`path` of the authentication file")
-	}
+	fs.StringArrayVarP(&opts.Configs, flagPrefix+"registry-config", "", nil, "`path` of the authentication file for "+notePrefix+"registry")
 }
 
 // Parse tries to read password with optional cmd prompt.

test/e2e/suite/auth/auth.go

@@ -30,7 +30,10 @@ var _ = Describe("Common registry user", Ordered, func() {
 
 		It("should run commands without logging in", func() {
 			RunWithoutLogin("attach", Host+"/repo:tag", "-a", "test=true", "--artifact-type", "doc/example")
-			RunWithoutLogin("copy", Host+"/repo:from", Host+"/repo:to")
+			ORAS("copy", Host+"/repo:from", Host+"/repo:to", "--from-registry-config", AuthConfigPath, "--to-registry-config", AuthConfigPath).
+				ExpectFailure().
+				MatchErrKeyWords("Error:", "credential required").
+				WithDescription("fail without logging in").Exec()
 			RunWithoutLogin("discover", Host+"/repo:tag")
 			RunWithoutLogin("push", "-a", "key=value", Host+"/repo:tag")
 			RunWithoutLogin("pull", Host+"/repo:tag")