feat: warn when picking up .grype.yaml from CWD

cmd/grype/cli/cli.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/anchore/clio"
 	"github.com/anchore/grype/cmd/grype/cli/commands"
+	"github.com/anchore/grype/cmd/grype/cli/internal/configwarn"
 	grypeHandler "github.com/anchore/grype/cmd/grype/cli/ui"
 	"github.com/anchore/grype/cmd/grype/internal/ui"
 	v6 "github.com/anchore/grype/grype/db/v6"
@@ -74,6 +75,10 @@ func SetupConfig(id clio.Identification) *clio.SetupConfig {
 				syft.SetLogger(state.Logger.Nested("from", "syft"))
 				stereoscope.SetLogger(state.Logger.Nested("from", "stereoscope"))
 
+				if path := configwarn.Detect(id.Name, os.Args, os.Getenv); path != "" {
+					state.Logger.Warnf("using configuration file from current directory: %s", path)
+				}
+
 				return nil
 			},
 		).

cmd/grype/cli/internal/configwarn/configwarn.go

@@ -0,0 +1,85 @@
+// Package configwarn detects when grype is about to pick up a configuration
+// file from the current working directory (e.g. ./.grype.yaml) without an
+// explicit --config flag or GRYPE_CONFIG environment variable. Reading a
+// hidden config file from the CWD silently can be a debugging hazard
+// (see anchore/grype#3427), so we surface a WARN-level log when it happens.
+package configwarn
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// supportedExts mirrors viper.SupportedExts. We hard-code the list rather
+// than depend on viper here so this package can be used without pulling the
+// configuration loader stack into tests.
+var supportedExts = []string{
+	"json", "toml", "yaml", "yml", "properties", "props", "prop",
+	"hcl", "tfvars", "dotenv", "env", "ini",
+}
+
+// fileExists is overridable for tests.
+var fileExists = func(path string) bool {
+	info, err := os.Stat(path)
+	return err == nil && !info.IsDir()
+}
+
+// Detect returns the path to a CWD-resident grype config file if one would
+// be picked up implicitly, otherwise it returns "".
+//
+// It returns "" (no warning) when:
+//   - the user passed an explicit -c / --config / --config=... flag
+//   - GRYPE_CONFIG (or the equivalent <appName>_CONFIG) is set
+//   - no recognised config file exists in the current working directory
+//
+// It looks for both finder layouts that fangs uses by default:
+//   - ./.<appName>.<ext>
+//   - ./.<appName>/config.<ext>
+func Detect(appName string, args []string, env func(string) string) string {
+	if explicitConfigFlag(args) {
+		return ""
+	}
+	envKey := strings.ToUpper(appName) + "_CONFIG"
+	if env != nil && env(envKey) != "" {
+		return ""
+	}
+
+	for _, ext := range supportedExts {
+		candidate := "." + appName + "." + ext
+		if fileExists(candidate) {
+			return candidate
+		}
+	}
+	subdir := "." + appName
+	for _, ext := range supportedExts {
+		candidate := filepath.Join(subdir, "config."+ext)
+		if fileExists(candidate) {
+			return candidate
+		}
+	}
+	return ""
+}
+
+// explicitConfigFlag returns true if a -c / --config flag appears in args
+// (in any of: "-c file", "--config file", "-c=file", "--config=file", or
+// the bundled short form "-cfoo"). We intentionally accept false positives
+// here over false negatives: if anything that looks like a config flag is
+// present, suppress the warning.
+func explicitConfigFlag(args []string) bool {
+	for i, a := range args {
+		switch {
+		case a == "-c", a == "--config":
+			if i+1 < len(args) {
+				return true
+			}
+		case strings.HasPrefix(a, "--config="):
+			return true
+		case strings.HasPrefix(a, "-c=") && len(a) > 3:
+			return true
+		case strings.HasPrefix(a, "-c") && len(a) > 2 && !strings.HasPrefix(a, "--"):
+			return true
+		}
+	}
+	return false
+}

cmd/grype/cli/internal/configwarn/configwarn_test.go

@@ -0,0 +1,135 @@
+package configwarn
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDetect(t *testing.T) {
+	tests := []struct {
+		name    string
+		app     string
+		args    []string
+		env     map[string]string
+		present []string
+		want    string
+	}{
+		{
+			name:    "no file present, no flag, no env",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: nil,
+			want:    "",
+		},
+		{
+			name:    "cwd .grype.yaml present and no flag/env",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    ".grype.yaml",
+		},
+		{
+			name:    "cwd .grype.yml present and no flag/env",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: []string{".grype.yml"},
+			want:    ".grype.yml",
+		},
+		{
+			name:    "cwd .grype.json present and no flag/env",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: []string{".grype.json"},
+			want:    ".grype.json",
+		},
+		{
+			name:    "cwd .grype/config.yaml present and no flag/env",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: []string{filepath.Join(".grype", "config.yaml")},
+			want:    filepath.Join(".grype", "config.yaml"),
+		},
+		{
+			name:    "explicit --config suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "--config", "/etc/grype.yaml", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "explicit --config= suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "--config=/etc/grype.yaml", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "explicit -c suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "-c", "/etc/grype.yaml", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "explicit -c=path suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "-c=/etc/grype.yaml", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "explicit -cpath bundled short form suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "-c/etc/grype.yaml", "alpine:latest"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "GRYPE_CONFIG env suppresses warning",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			env:     map[string]string{"GRYPE_CONFIG": "/etc/grype.yaml"},
+			present: []string{".grype.yaml"},
+			want:    "",
+		},
+		{
+			name:    "trailing -c with no value is not treated as explicit",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest", "-c"},
+			present: []string{".grype.yaml"},
+			want:    ".grype.yaml",
+		},
+		{
+			name:    "subdir form is only checked after the flat form",
+			app:     "grype",
+			args:    []string{"grype", "alpine:latest"},
+			present: []string{".grype.yaml", filepath.Join(".grype", "config.yaml")},
+			want:    ".grype.yaml",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			present := map[string]struct{}{}
+			for _, p := range tt.present {
+				present[p] = struct{}{}
+			}
+			origExists := fileExists
+			fileExists = func(path string) bool {
+				_, ok := present[path]
+				return ok
+			}
+			t.Cleanup(func() { fileExists = origExists })
+
+			env := func(string) string { return "" }
+			if tt.env != nil {
+				env = func(k string) string { return tt.env[k] }
+			}
+
+			got := Detect(tt.app, tt.args, env)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}