feat: allow override env RESTIC_HOST with flag to filter all snapshots (#5541)

changelog/unreleased/issue-5440

@@ -0,0 +1,12 @@
+Enhancement: Allow overriding RESTIC_HOST environment variable with --host flag
+
+When the `RESTIC_HOST` environment variable was set, there was no way to list or
+operate on snapshots from all hosts, as the environment variable would always
+filter to that specific host. Restic now allows overriding `RESTIC_HOST` by
+explicitly providing the `--host` flag with an empty string (e.g., `--host=""` or
+`--host=`), which will show snapshots from all hosts. This works for all commands
+that support snapshot filtering: `snapshots`, `forget`, `find`, `stats`, `copy`,
+`tag`, `repair snapshots`, `rewrite`, `mount`, `restore`, `dump`, and `ls`.
+
+https://github.com/restic/restic/issues/5440
+https://github.com/restic/restic/pull/5541

cmd/restic/cmd_copy.go

@@ -49,6 +49,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runCopy(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_dump.go

@@ -48,6 +48,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runDump(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_find.go

@@ -52,6 +52,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runFind(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_forget.go

@@ -50,6 +50,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runForget(cmd.Context(), opts, pruneOpts, *globalOptions, globalOptions.term, args)
 		},
 	}

cmd/restic/cmd_forget_test.go

@@ -96,7 +96,38 @@ func TestForgetOptionValues(t *testing.T) {
 
 func TestForgetHostnameDefaulting(t *testing.T) {
 	t.Setenv("RESTIC_HOST", "testhost")
-	opts := ForgetOptions{}
+
-	opts.AddFlags(pflag.NewFlagSet("test", pflag.ContinueOnError))
+	tests := []struct {
-	rtest.Equals(t, []string{"testhost"}, opts.Hosts)
+		name string
+		args []string
+		want []string
+	}{
+		{
+			name: "env default when flag not set",
+			args: nil,
+			want: []string{"testhost"},
+		},
+		{
+			name: "flag overrides env",
+			args: []string{"--host", "flaghost"},
+			want: []string{"flaghost"},
+		},
+		{
+			name: "empty flag clears env",
+			args: []string{"--host", ""},
+			want: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			set := pflag.NewFlagSet(tt.name, pflag.ContinueOnError)
+			opts := ForgetOptions{}
+			opts.AddFlags(set)
+			err := set.Parse(tt.args)
+			rtest.Assert(t, err == nil, "expected no error for input")
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
+			rtest.Equals(t, tt.want, opts.Hosts)
+		})
+	}
 }

cmd/restic/cmd_ls.go

@@ -61,6 +61,7 @@ Exit status is 12 if the password is incorrect.
 		DisableAutoGenTag: true,
 		GroupID:           cmdGroupDefault,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runLs(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_mount.go

@@ -82,6 +82,7 @@ Exit status is 12 if the password is incorrect.
 		DisableAutoGenTag: true,
 		GroupID:           cmdGroupDefault,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runMount(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_repair_snapshots.go

@@ -51,6 +51,7 @@ Exit status is 12 if the password is incorrect.
 `,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runRepairSnapshots(cmd.Context(), *globalOptions, opts, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_restore.go

@@ -46,6 +46,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runRestore(cmd.Context(), opts, *globalOptions, globalOptions.term, args)
 		},
 	}

cmd/restic/cmd_rewrite.go

@@ -61,6 +61,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runRewrite(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_snapshots.go

@@ -37,6 +37,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runSnapshots(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_stats.go

@@ -64,6 +64,7 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runStats(cmd.Context(), opts, *globalOptions, args, globalOptions.term)
 		},
 	}

cmd/restic/cmd_tag.go

@@ -40,6 +40,8 @@ Exit status is 12 if the password is incorrect.
 		GroupID:           cmdGroupDefault,
 		DisableAutoGenTag: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
+			finalizeSnapshotFilter(&opts.SnapshotFilter)
 			return runTag(cmd.Context(), opts, *globalOptions, globalOptions.term, args)
 		},
 	}

cmd/restic/find.go

@@ -12,33 +12,41 @@ import (
 
 // initMultiSnapshotFilter is used for commands that work on multiple snapshots
 // MUST be combined with restic.FindFilteredSnapshots or FindFilteredSnapshots
+// MUST be followed by finalizeSnapshotFilter after flag parsing
 func initMultiSnapshotFilter(flags *pflag.FlagSet, filt *data.SnapshotFilter, addHostShorthand bool) {
 	hostShorthand := "H"
 	if !addHostShorthand {
 		hostShorthand = ""
 	}
-	flags.StringArrayVarP(&filt.Hosts, "host", hostShorthand, nil, "only consider snapshots for this `host` (can be specified multiple times) (default: $RESTIC_HOST)")
+	flags.StringArrayVarP(&filt.Hosts, "host", hostShorthand, nil, "only consider snapshots for this `host` (can be specified multiple times, use empty string to unset default value) (default: $RESTIC_HOST)")
 	flags.Var(&filt.Tags, "tag", "only consider snapshots including `tag[,tag,...]` (can be specified multiple times)")
 	flags.StringArrayVar(&filt.Paths, "path", nil, "only consider snapshots including this (absolute) `path` (can be specified multiple times, snapshots must include all specified paths)")
-
-	// set default based on env if set
-	if host := os.Getenv("RESTIC_HOST"); host != "" {
-		filt.Hosts = []string{host}
-	}
 }
 
 // initSingleSnapshotFilter is used for commands that work on a single snapshot
 // MUST be combined with restic.FindFilteredSnapshot
+// MUST be followed by finalizeSnapshotFilter after flag parsing
 func initSingleSnapshotFilter(flags *pflag.FlagSet, filt *data.SnapshotFilter) {
-	flags.StringArrayVarP(&filt.Hosts, "host", "H", nil, "only consider snapshots for this `host`, when snapshot ID \"latest\" is given (can be specified multiple times) (default: $RESTIC_HOST)")
+	flags.StringArrayVarP(&filt.Hosts, "host", "H", nil, "only consider snapshots for this `host`, when snapshot ID \"latest\" is given (can be specified multiple times, use empty string to unset default value) (default: $RESTIC_HOST)")
 	flags.Var(&filt.Tags, "tag", "only consider snapshots including `tag[,tag,...]`, when snapshot ID \"latest\" is given (can be specified multiple times)")
 	flags.StringArrayVar(&filt.Paths, "path", nil, "only consider snapshots including this (absolute) `path`, when snapshot ID \"latest\" is given (can be specified multiple times, snapshots must include all specified paths)")
+}
 
-	// set default based on env if set
+// finalizeSnapshotFilter applies RESTIC_HOST default only if --host flag wasn't explicitly set.
+// This allows users to override RESTIC_HOST by providing --host="" or --host with explicit values.
+func finalizeSnapshotFilter(filt *data.SnapshotFilter) {
+	// Only apply RESTIC_HOST default if the --host flag wasn't changed by the user
+	if filt.Hosts == nil {
 		if host := os.Getenv("RESTIC_HOST"); host != "" {
 			filt.Hosts = []string{host}
 		}
 	}
+	// If flag was set to empty string explicitly (e.g., --host=""),
+	// filt.Hosts will be []string{""} which should be cleaned up to allow all hosts
+	if len(filt.Hosts) == 1 && filt.Hosts[0] == "" {
+		filt.Hosts = nil
+	}
+}
 
 // FindFilteredSnapshots yields Snapshots, either given explicitly by `snapshotIDs` or filtered from the list of all snapshots.
 func FindFilteredSnapshots(ctx context.Context, be restic.Lister, loader restic.LoaderUnpacked, f *data.SnapshotFilter, snapshotIDs []string, printer progress.Printer) <-chan *data.Snapshot {

cmd/restic/find_test.go

@@ -39,6 +39,24 @@ func TestSnapshotFilter(t *testing.T) {
 			[]string{"abc"},
 			"def",
 		},
+		{
+			"env set, empty flag overrides",
+			[]string{"--host", ""},
+			nil, // empty host filter means all hosts
+			"envhost",
+		},
+		{
+			"env set, multiple flags override",
+			[]string{"--host", "host1", "--host", "host2"},
+			[]string{"host1", "host2"},
+			"envhost",
+		},
+		{
+			"env set, multiple hosts including empty",
+			[]string{"--host", "host1", "--host", ""},
+			[]string{"host1", ""},
+			"envhost",
+		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			t.Setenv("RESTIC_HOST", test.env)
@@ -54,6 +72,9 @@ func TestSnapshotFilter(t *testing.T) {
 				err := set.Parse(test.args)
 				rtest.OK(t, err)
 
+				// Apply the finalization logic to handle env defaults
+				finalizeSnapshotFilter(flt)
+
 				rtest.Equals(t, test.expected, flt.Hosts, "unexpected hosts")
 			}
 		})