Make sync config a positional argument

README.md

@@ -90,19 +90,25 @@ artifacts:
 Run the sync:
 
 ```shell
-flux-mirror sync -c flux-mirror.yaml
+flux-mirror sync flux-mirror.yaml
+```
+
+You can also read the config from stdin:
+
+```shell
+flux-mirror sync - < flux-mirror.yaml
 ```
 
 Preview without writing:
 
 ```shell
-flux-mirror sync -c flux-mirror.yaml --dry-run
+flux-mirror sync flux-mirror.yaml --dry-run
 ```
 
 Force a resync of drifted tags e.g. `latest`:
 
 ```shell
-flux-mirror sync -c flux-mirror.yaml --overwrite
+flux-mirror sync flux-mirror.yaml --overwrite
 ```
 
 See [`examples/`](examples) for more configurations and
@@ -122,13 +128,13 @@ real failures from drift, so a CI gate can react to each independently:
 The `--no-progress` flag suppresses the live spinner so log output stays clean in CI:
 
 ```shell
-flux-mirror sync -c flux-mirror.yaml --no-progress
+flux-mirror sync flux-mirror.yaml --no-progress
 ```
 
 For downstream tooling, emit a structured report:
 
 ```shell
-flux-mirror sync -c flux-mirror.yaml -o json | jq '.entries[].outcomes'
+flux-mirror sync flux-mirror.yaml -o json | jq '.entries[].outcomes'
 ```
 
 ### GitHub Actions
@@ -164,7 +170,7 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Sync Kubernetes SIGs Charts
-        run: flux-mirror sync -c kubernetes-sigs.yaml --no-progress
+        run: flux-mirror sync kubernetes-sigs.yaml --no-progress
 ```
 
 ### Docker
@@ -176,7 +182,7 @@ docker run --rm \
   -e DOCKER_CONFIG=/.docker \
   -v "$PWD/flux-mirror.yaml:/config.yaml:ro" \
   -v "$HOME/.docker/config.json:/.docker/config.json:ro" \
-  ghcr.io/fluxcd/flux-mirror:latest sync -c /config.yaml --no-progress
+  ghcr.io/fluxcd/flux-mirror:latest sync /config.yaml --no-progress
 ```
 
 ### Kubernetes
@@ -191,7 +197,7 @@ destination registry credentials from a `Secret` created via
 
 | Command                       | Description                                                       |
 |-------------------------------|-------------------------------------------------------------------|
-| `flux-mirror sync [-c PATH]`  | Mirror Helm charts and OCI artifacts described by a YAML config.  |
+| `flux-mirror sync CONFIG|-`   | Mirror Helm charts and OCI artifacts described by a YAML config.  |
 | `flux-mirror version`         | Print the CLI version.                                            |
 
 Run `flux-mirror <command> --help` for the full flag list.

actions/setup/README.md

@@ -35,7 +35,7 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Sync
-        run: flux-mirror sync -c .flux-mirror.yaml --no-progress
+        run: flux-mirror sync .flux-mirror.yaml --no-progress
 ```
 
 `flux-mirror sync` exits with `1` on a pull/push failure and `2` when drift is detected.

cmd/flux-mirror/main_test.go

@@ -6,6 +6,7 @@ package main
 import (
 	"bytes"
 	"os"
+	"strings"
 	"testing"
 	"time"
 
@@ -27,11 +28,16 @@ func TestMain(m *testing.M) {
 // arguments to their default values after execution to
 // ensure test isolation.
 func executeCommand(args []string) (string, error) {
+	return executeCommandWithInput(args, "")
+}
+
+func executeCommandWithInput(args []string, input string) (string, error) {
 	defer resetCmdArgs()
 
 	buf := new(bytes.Buffer)
 	cmd := rootCmd
 	cmd.SetArgs(args)
+	cmd.SetIn(strings.NewReader(input))
 	cmd.SetOut(buf)
 	cmd.SetErr(buf)
 
@@ -41,6 +47,7 @@ func executeCommand(args []string) (string, error) {
 
 func resetCmdArgs() {
 	rootArgs.timeout = timeout
+	rootCmd.SetIn(os.Stdin)
 
 	versionArgs = versionFlags{output: "text"}
 	syncArgs = syncFlags{output: "text", concurrency: 4, retries: 3}

cmd/flux-mirror/sync.go

@@ -29,7 +29,7 @@ const (
 )
 
 var syncCmd = &cobra.Command{
-	Use:   "sync",
+	Use:   "sync [CONFIG|-]",
 	Short: "Mirror Helm charts and OCI artifacts to a destination registry",
 	Long: `Mirror Helm charts and OCI artifacts between registries based on a
 declarative YAML config (apiVersion: mirror.fluxcd.io/v1alpha1, kind: Config).
@@ -41,22 +41,24 @@ Exit codes:
   1  at least one tag job failed
   2  no failures, but at least one tag drifted (overwrite=false)`,
 	Example: `  # Run a sync against a config file
-  flux-mirror sync -c flux-mirror.yaml
+  flux-mirror sync flux-mirror.yaml
 
   # Pass the config via env var
   FLUX_MIRROR_CONFIG=flux-mirror.yaml flux-mirror sync
 
+  # Pass the config via stdin
+  flux-mirror sync - < flux-mirror.yaml
+
   # Preview without writing to the destination
-  flux-mirror sync -c flux-mirror.yaml --dry-run -o yaml
+  flux-mirror sync flux-mirror.yaml --dry-run -o yaml
 
   # Force overwrite of every drifted tag
-  flux-mirror sync -c flux-mirror.yaml --overwrite`,
-	Args: cobra.NoArgs,
+  flux-mirror sync flux-mirror.yaml --overwrite`,
+	Args: cobra.MaximumNArgs(1),
 	RunE: syncCmdRun,
 }
 
 type syncFlags struct {
-	config          string
 	output          flags.Output
 	concurrency     int
 	retries         int
@@ -79,8 +81,6 @@ var syncArgs = syncFlags{
 }
 
 func init() {
-	syncCmd.Flags().StringVarP(&syncArgs.config, "config", "c", "",
-		"Path to the YAML config file (or set "+envConfig+").")
 	syncCmd.Flags().VarP(&syncArgs.output, "output", "o", syncArgs.output.Description())
 	syncCmd.Flags().IntVar(&syncArgs.concurrency, "concurrency", syncArgs.concurrency,
 		"Maximum number of copy operations to run in parallel per job")
@@ -123,12 +123,12 @@ func init() {
 	rootCmd.AddCommand(syncCmd)
 }
 
-func syncCmdRun(cmd *cobra.Command, _ []string) error {
-	cfgPath, err := resolveConfigPath()
+func syncCmdRun(cmd *cobra.Command, args []string) error {
+	cfgPath, err := resolveConfigPath(args)
 	if err != nil {
 		return err
 	}
-	cfg, err := config.Load(cfgPath)
+	cfg, err := loadConfig(cmd, cfgPath)
 	if err != nil {
 		return err
 	}
@@ -309,12 +309,26 @@ func buildClientTransport() (http.RoundTripper, error) {
 	return t, nil
 }
 
-func resolveConfigPath() (string, error) {
-	if syncArgs.config != "" {
-		return syncArgs.config, nil
+func resolveConfigPath(args []string) (string, error) {
+	if len(args) > 0 {
+		return args[0], nil
 	}
 	if env := os.Getenv(envConfig); env != "" {
 		return env, nil
 	}
-	return "", fmt.Errorf("config required: pass --config/-c or set %s", envConfig)
+	return "", fmt.Errorf("config required: pass the config path as the first argument, pass '-' for stdin, or set %s", envConfig)
+}
+
+func loadConfig(cmd *cobra.Command, path string) (*config.Config, error) {
+	if path != "-" {
+		return config.Load(path)
+	}
+	cfg, err := config.Decode(cmd.InOrStdin())
+	if err != nil {
+		return nil, err
+	}
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+	return cfg, nil
 }

cmd/flux-mirror/sync_test.go

@@ -20,6 +20,7 @@ var dockerReg string
 
 func ensureRegistry(t *testing.T) {
 	t.Helper()
+	testregistry.UseEmptyDockerConfig(t)
 	if dockerReg != "" {
 		return
 	}
@@ -33,7 +34,14 @@ func ensureRegistry(t *testing.T) {
 func writeConfig(t *testing.T, src, dst string) string {
 	t.Helper()
 	g := NewWithT(t)
-	body := fmt.Sprintf(`apiVersion: mirror.fluxcd.io/v1alpha1
+	body := configBody(src, dst)
+	path := filepath.Join(t.TempDir(), "config.yaml")
+	g.Expect(os.WriteFile(path, []byte(body), 0o600)).To(Succeed())
+	return path
+}
+
+func configBody(src, dst string) string {
+	return fmt.Sprintf(`apiVersion: mirror.fluxcd.io/v1alpha1
 kind: Config
 artifacts:
   - source: %s
@@ -42,9 +50,6 @@ artifacts:
       semver: ">=0.0.0"
       limit: 5
 `, src, dst)
-	path := filepath.Join(t.TempDir(), "config.yaml")
-	g.Expect(os.WriteFile(path, []byte(body), 0o600)).To(Succeed())
-	return path
 }
 
 func TestSync_NoConfigError(t *testing.T) {
@@ -73,7 +78,22 @@ func TestSync_ConfigViaEnv(t *testing.T) {
 	g.Expect(out).To(ContainSubstring(`"1.0.0"`))
 }
 
-func TestSync_FlagOverridesEnv(t *testing.T) {
+func TestSync_ConfigViaStdin(t *testing.T) {
+	g := NewWithT(t)
+	ensureRegistry(t)
+
+	src := dockerReg + "/stdin-src-" + testregistry.RandSuffix()
+	dst := dockerReg + "/stdin-dst-" + testregistry.RandSuffix()
+	testregistry.PushImage(t, src+":1.0.0")
+	t.Setenv("FLUX_MIRROR_CONFIG", "")
+
+	out, err := executeCommandWithInput([]string{"sync", "-", "--insecure", "-o", "json"}, configBody(src, dst))
+	g.Expect(err).ToNot(HaveOccurred())
+	g.Expect(out).To(ContainSubstring(`"copied": [`))
+	g.Expect(out).To(ContainSubstring(`"1.0.0"`))
+}
+
+func TestSync_ArgOverridesEnv(t *testing.T) {
 	g := NewWithT(t)
 	ensureRegistry(t)
 
@@ -82,10 +102,10 @@ func TestSync_FlagOverridesEnv(t *testing.T) {
 	testregistry.PushImage(t, src+":1.0.0")
 
 	cfgPath := writeConfig(t, src, dst)
-	// Env points at a bogus path — the flag must win.
+	// Env points at a bogus path — the positional argument must win.
 	t.Setenv("FLUX_MIRROR_CONFIG", "/nonexistent/path.yaml")
 
-	out, err := executeCommand([]string{"sync", "-c", cfgPath, "--insecure", "--verbose"})
+	out, err := executeCommand([]string{"sync", cfgPath, "--insecure", "--verbose"})
 	g.Expect(err).ToNot(HaveOccurred())
 	g.Expect(out).To(ContainSubstring(src))
 }
@@ -102,7 +122,7 @@ func TestSync_DriftExitCode(t *testing.T) {
 	cfgPath := writeConfig(t, src, dst)
 	t.Setenv("FLUX_MIRROR_CONFIG", "")
 
-	_, err := executeCommand([]string{"sync", "-c", cfgPath, "--insecure"})
+	_, err := executeCommand([]string{"sync", cfgPath, "--insecure"})
 	g.Expect(err).To(HaveOccurred())
 	var ec interface{ ExitCode() int }
 	g.Expect(errors.As(err, &ec)).To(BeTrue())
@@ -120,14 +140,14 @@ func TestSync_DryRun(t *testing.T) {
 	cfgPath := writeConfig(t, src, dst)
 	t.Setenv("FLUX_MIRROR_CONFIG", "")
 
-	out, err := executeCommand([]string{"sync", "-c", cfgPath, "--insecure", "--dry-run", "-o", "yaml"})
+	out, err := executeCommand([]string{"sync", cfgPath, "--insecure", "--dry-run", "-o", "yaml"})
 	g.Expect(err).ToNot(HaveOccurred())
 	g.Expect(out).To(MatchRegexp(`would-copy:\s*\n\s*- 1\.0\.0`))
 }
 
 func TestSync_BadOutputFormat(t *testing.T) {
 	g := NewWithT(t)
 	cfgPath := writeConfig(t, "ghcr.io/a/b", "ghcr.io/c/d")
-	_, err := executeCommand([]string{"sync", "-c", cfgPath, "-o", "xml"})
+	_, err := executeCommand([]string{"sync", cfgPath, "-o", "xml"})
 	g.Expect(err).To(HaveOccurred())
 }

docs/config.md

@@ -10,8 +10,9 @@ The config uses a Kubernetes-style `apiVersion`/`kind` fields. It is not a
 Kubernetes resource; it is a CLI config consumed by `flux-mirror`, the same
 way `kustomization.yaml` is consumed by `kustomize`.
 
-`flux-mirror sync` reads the file path from `--config` / `-c`, falling back
-to `FLUX_MIRROR_CONFIG`. The flag wins when both are set.
+`flux-mirror sync` reads the file path from the first positional argument,
+falling back to `FLUX_MIRROR_CONFIG`. Use `-` as the argument to read YAML
+from stdin. The argument wins when both are set.
 
 ## Top-level fields