fix(restic): handle repo exists check for < v0.17.0

cmd/standard-backups-restic-backend/restic.go

@@ -2,16 +2,28 @@ package main
 
 import (
 	"bytes"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 	"os/exec"
+	"regexp"
+
+	"github.com/hashicorp/go-version"
 )
 
+func resticBin() string {
+	restic := os.Getenv("RESTIC")
+	if restic == "" {
+		restic = "restic"
+	}
+	return restic
+}
+
 func resticCmd(repo string, env map[string]string, args ...string) *exec.Cmd {
 	finalArgs := []string{"--repo", repo}
 	finalArgs = append(finalArgs, args...)
-	cmd := exec.Command("restic", finalArgs...)
+	cmd := exec.Command(resticBin(), finalArgs...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 
@@ -42,16 +54,61 @@ func resticOutput(repo string, env map[string]string, args ...string) ([]byte, e
 	return output.Bytes(), nil
 }
 
+func resticRawVersion() (string, error) {
+	cmd := exec.Command(resticBin(), "version", "--json")
+	stdout := bytes.NewBuffer(nil)
+	cmd.Stdout = stdout
+	err := cmd.Run()
+	if err != nil {
+		return "", err
+	}
+	output := stdout.Bytes()
+	var versionMessage struct {
+		Version string `json:"version"`
+	}
+	err = json.Unmarshal(output, &versionMessage)
+	if err == nil {
+		return versionMessage.Version, nil
+	}
+
+	// Older versions don't honor `--json` on `restic version`. Parsing out manually.
+	versionRegexp := regexp.MustCompile(`^restic (\d+\.\d+\.\d+) compiled`)
+	matches := versionRegexp.FindSubmatch(output)
+	if matches == nil {
+		return "", fmt.Errorf("could not parse restic version from '%s'", output)
+	}
+	return string(matches[1]), nil
+}
+
+func resticVersion() (*version.Version, error) {
+	raw, err := resticRawVersion()
+	if err != nil {
+		return nil, fmt.Errorf("failed to determine restic version: %w", err)
+	}
+	res, err := version.NewVersion(raw)
+	if err != nil {
+		return nil, fmt.Errorf("failed to determine restic version (raw=%s): %w", raw, err)
+	}
+	return res, nil
+}
+
 func checkRepoExists(repo string, env map[string]string) (bool, error) {
 	cmd := resticCmd(repo, env, "cat", "config")
 	cmd.Stderr = nil
 	cmd.Stdout = nil
 
 	err := cmd.Run()
 	var exitError *exec.ExitError
-	if errors.As(err, &exitError) &&
-		exitError.ExitCode() == 10 /*repo does not exist*/ {
-		return false, nil
+	if errors.As(err, &exitError) {
+		v, err := resticVersion()
+		if err != nil {
+			return false, fmt.Errorf("failed to check if repo %s exists: %w", repo, err)
+		}
+		if v.LessThan(version.Must(version.NewVersion("0.17.0"))) /*no dedicated exit code*/ ||
+			exitError.ExitCode() == 10 /*repo does not exist*/ {
+			return false, nil
+		}
+		return false, fmt.Errorf("failed to check if repo %s exists: %w", repo, err)
 	} else if err != nil {
 		return false, fmt.Errorf("failed to check if repo %s exists: %w", repo, err)
 	}

cmd/standard-backups-restic-backend/restic_test.go

@@ -1,9 +1,13 @@
 package main
 
 import (
+	"fmt"
+	"os"
+	"os/exec"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestOptionsToArgs(t *testing.T) {
@@ -57,3 +61,38 @@ func TestOptionsToArgs(t *testing.T) {
 		})
 	}
 }
+
+func TestCheckRepoExists(t *testing.T) {
+	tests := map[string]string{
+		"system": "restic",
+	}
+	restic016, ok := os.LookupEnv("RESTIC_0_16")
+	if ok {
+		tests["0.16"] = fmt.Sprintf("%s/bin/restic", restic016)
+	}
+	for name, restic := range tests {
+		t.Run(name, func(t *testing.T) {
+			t.Setenv("RESTIC", restic)
+			t.Run("exists", func(t *testing.T) {
+				repo := t.TempDir()
+				cmd := exec.Command(restic, "init", "--repo", repo)
+				cmd.Env = append(cmd.Env, "RESTIC_PASSWORD=supersecret")
+				cmd.Stdout = os.Stdout
+				cmd.Stderr = os.Stderr
+				err := cmd.Run()
+				require.NoError(t, err)
+
+				res, err := checkRepoExists(repo, map[string]string{
+					"RESTIC_PASSWORD": "supersecret",
+				})
+				assert.NoError(t, err)
+				assert.True(t, res)
+			})
+			t.Run("not-exists", func(t *testing.T) {
+				res, err := checkRepoExists(t.TempDir(), map[string]string{})
+				assert.NoError(t, err)
+				assert.False(t, res)
+			})
+		})
+	}
+}

flake.nix

@@ -17,6 +17,19 @@
       '';
 
       devShells.default = pkgs.mkShell {
+        # This old version of restic doesn't return the right status code when a
+        # repository is not found. We want to support it too because it's still
+        # in use in ubuntu 24.04.
+        RESTIC_0_16 = pkgs.restic.overrideAttrs (final: previous: rec {
+          version = "0.16.5";
+          src = pkgs.fetchFromGitHub {
+            owner = "restic";
+            repo = "restic";
+            rev = "v${version}";
+            hash = "sha256-WwySXQU8eoyQRcI+zF+pIIKLEFheTnqkPTw0IZeUrhA=";
+          };
+          vendorHash = "sha256-VZTX0LPZkqN4+OaaIkwepbGwPtud8Cu7Uq7t1bAUC8M=";
+        });
         hardeningDisable = [
           "fortify" # required to use delve debugger
         ];

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/go-viper/mapstructure/v2 v2.5.0
 	github.com/goccy/go-yaml v1.19.2
 	github.com/gookit/color v1.6.0
+	github.com/hashicorp/go-version v1.8.0
 	github.com/k0kubun/pp/v3 v3.5.1
 	github.com/lithammer/dedent v1.1.0
 	github.com/olekukonko/tablewriter v1.1.4

go.sum

@@ -27,6 +27,8 @@ github.com/gookit/assert v0.1.1 h1:lh3GcawXe/p+cU7ESTZ5Ui3Sm/x8JWpIis4/1aF0mY0=
 github.com/gookit/assert v0.1.1/go.mod h1:jS5bmIVQZTIwk42uXl4lyj4iaaxx32tqH16CFj0VX2E=
 github.com/gookit/color v1.6.0 h1:JjJXBTk1ETNyqyilJhkTXJYYigHG24TM9Xa2M1xAhRA=
 github.com/gookit/color v1.6.0/go.mod h1:9ACFc7/1IpHGBW8RwuDm/0YEnhg3dwwXpoMsmtyHfjs=
+github.com/hashicorp/go-version v1.8.0 h1:KAkNb1HAiZd1ukkxDFGmokVZe1Xy9HG6NUp+bPle2i4=
+github.com/hashicorp/go-version v1.8.0/go.mod h1:fltr4n8CU8Ke44wwGCBoEymUuxUHl09ZGVZPK5anwXA=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/k0kubun/pp/v3 v3.5.1 h1:fS8Xt0MWVVSiKwfXeIdE0WJlktdA87/gt0Hs0+j2R2s=