fix: make caching options more explicit (#2966)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

cmd/syft/internal/options/cache.go

@@ -24,17 +24,26 @@ type Cache struct {
 }
 
 func (c *Cache) DescribeFields(descriptions clio.FieldDescriptionSet) {
-	descriptions.Add(&c.Dir, "root directory to cache any downloaded content")
+	descriptions.Add(&c.Dir, "root directory to cache any downloaded content; empty string will use an in-memory cache")
-	descriptions.Add(&c.TTL, "time to live for cached data")
+	descriptions.Add(&c.TTL, "time to live for cached data; setting this to 0 will disable caching entirely")
 }
 
 func (c *Cache) PostLoad() error {
-	if c.Dir != "" {
 	ttl, err := parseDuration(c.TTL)
 	if err != nil {
 		log.Warnf("unable to parse duration '%v', using default (%s) due to: %v", c.TTL, durationToString(defaultTTL()), err)
 		ttl = defaultTTL()
 	}
+	// if TTL is <= 0, disable caching entirely
+	if ttl <= 0 {
+		cache.SetManager(nil)
+		return nil
+	}
+	// if dir == "" but we have a TTL, use an in-memory cache
+	if c.Dir == "" {
+		cache.SetManager(cache.NewInMemory(ttl))
+		return nil
+	}
 	dir, err := homedir.Expand(c.Dir)
 	if err != nil {
 		log.Warnf("unable to expand cache directory %s: %v", c.Dir, err)
@@ -48,7 +57,6 @@ func (c *Cache) PostLoad() error {
 			cache.SetManager(m)
 		}
 	}
-	}
 	return nil
 }
 
@@ -100,9 +108,8 @@ func durationToString(duration time.Duration) string {
 	return out
 }
 
-var whitespace = regexp.MustCompile(`\s+`)
-
 func parseDuration(duration string) (time.Duration, error) {
+	whitespace := regexp.MustCompile(`\s+`)
 	duration = strings.ToLower(whitespace.ReplaceAllString(duration, ""))
 	parts := strings.SplitN(duration, "d", 2)
 	var days time.Duration
@@ -114,7 +121,9 @@ func parseDuration(duration string) (time.Duration, error) {
 			return 0, daysErr
 		}
 		days = time.Duration(numDays) * 24 * time.Hour
+		if len(parts[1]) > 0 {
 			remain, err = time.ParseDuration(parts[1])
+		}
 	} else {
 		remain, err = time.ParseDuration(duration)
 	}

cmd/syft/internal/options/cache_test.go

@@ -1,6 +1,7 @@
 package options
 
 import (
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -10,6 +11,9 @@ import (
 	"github.com/adrg/xdg"
 	"github.com/mitchellh/go-homedir"
 	"github.com/stretchr/testify/require"
+
+	"github.com/anchore/syft/internal"
+	"github.com/anchore/syft/internal/cache"
 )
 
 func Test_defaultDir(t *testing.T) {
@@ -91,12 +95,135 @@ func Test_defaultDir(t *testing.T) {
 	}
 }
 
+func Test_cacheOptions(t *testing.T) {
+	tmp := t.TempDir()
+	tests := []struct {
+		name string
+		opts Cache
+		test func(t *testing.T)
+	}{
+		{
+			name: "disable-1",
+			opts: Cache{
+				Dir: "some-dir",
+				TTL: "0",
+			},
+			test: func(t *testing.T) {
+				c := cache.GetManager().GetCache("test-disable-1", "v-disable-1")
+				err := c.Write("key-disable-1", strings.NewReader("some-value-disable-1"))
+				require.NoError(t, err)
+				rdr, err := c.Read("key-disable-1")
+				require.Nil(t, rdr)
+				require.Error(t, err)
+			},
+		},
+		{
+			name: "disable-2",
+			opts: Cache{
+				Dir: "some-dir",
+				TTL: "0s",
+			},
+			test: func(t *testing.T) {
+				c := cache.GetManager().GetCache("test-disable-2", "v-disable-2")
+				err := c.Write("key-disable-2", strings.NewReader("some-value-disable-2"))
+				require.NoError(t, err)
+				rdr, err := c.Read("key-disable-2")
+				require.Nil(t, rdr)
+				require.Error(t, err)
+			},
+		},
+
+		{
+			name: "disable-3",
+			opts: Cache{
+				Dir: "some-dir",
+				TTL: "0d",
+			},
+			test: func(t *testing.T) {
+				c := cache.GetManager().GetCache("test-disable-3", "v-disable-3")
+				err := c.Write("key-disable-3", strings.NewReader("some-value-disable-3"))
+				require.NoError(t, err)
+				rdr, err := c.Read("key-disable-3")
+				require.Nil(t, rdr)
+				require.Error(t, err)
+			},
+		},
+		{
+			name: "in-memory",
+			opts: Cache{
+				Dir: "",
+				TTL: "10m",
+			},
+			test: func(t *testing.T) {
+				c := cache.GetManager().GetCache("test-mem", "v-mem")
+				err := c.Write("key-mem", strings.NewReader("some-value-mem"))
+				require.NoError(t, err)
+				rdr, err := c.Read("key-mem")
+				require.NotNil(t, rdr)
+				defer internal.CloseAndLogError(rdr, "")
+				require.NoError(t, err)
+				data, err := io.ReadAll(rdr)
+				require.NoError(t, err)
+				require.Equal(t, "some-value-mem", string(data))
+				require.NoDirExists(t, filepath.Join("test-mem", "v-mem"))
+			},
+		},
+		{
+			name: "on disk",
+			opts: Cache{
+				Dir: tmp,
+				TTL: "10m",
+			},
+			test: func(t *testing.T) {
+				c := cache.GetManager().GetCache("test-disk", "v-disk")
+				err := c.Write("key-disk", strings.NewReader("some-value-disk"))
+				require.NoError(t, err)
+				rdr, err := c.Read("key-disk")
+				require.NotNil(t, rdr)
+				defer internal.CloseAndLogError(rdr, "")
+				require.NoError(t, err)
+				data, err := io.ReadAll(rdr)
+				require.NoError(t, err)
+				require.Equal(t, "some-value-disk", string(data))
+				require.DirExists(t, filepath.Join(tmp, "test-disk", "v-disk"))
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			original := cache.GetManager()
+			defer cache.SetManager(original)
+
+			err := test.opts.PostLoad()
+			require.NoError(t, err)
+
+			test.test(t)
+		})
+	}
+}
+
 func Test_parseDuration(t *testing.T) {
 	tests := []struct {
 		duration string
 		expect   time.Duration
 		err      require.ErrorAssertionFunc
 	}{
+		{
+			duration: "0d",
+			expect:   0,
+		},
+		{
+			duration: "0m",
+			expect:   0,
+		},
+		{
+			duration: "0s",
+			expect:   0,
+		},
+		{
+			duration: "0",
+			expect:   0,
+		},
 		{
 			duration: "1d",
 			expect:   24 * time.Hour,
@@ -141,6 +268,8 @@ func Test_parseDuration(t *testing.T) {
 			if test.err != nil {
 				test.err(t, err)
 				return
+			} else {
+				require.NoError(t, err)
 			}
 			require.Equal(t, test.expect, got)
 		})

internal/cache/cache.go

@@ -36,7 +36,8 @@ func GetManager() Manager {
 	return manager
 }
 
-// SetManager sets the global cache manager, which is used to instantiate all caches
+// SetManager sets the global cache manager, which is used to instantiate all caches.
+// Setting this to nil disables caching.
 func SetManager(m Manager) {
 	if m == nil {
 		manager = &bypassedCache{}

internal/cache/cache_test.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -10,8 +11,18 @@ func Test_SetManager(t *testing.T) {
 	original := GetManager()
 	defer SetManager(original)
 
+	SetManager(nil)
+
+	require.NotNil(t, GetManager())
+	require.IsType(t, &bypassedCache{}, GetManager())
+
 	SetManager(NewInMemory(0))
 
+	require.NotNil(t, GetManager())
+	require.IsType(t, &bypassedCache{}, GetManager())
+
+	SetManager(NewInMemory(1 * time.Hour))
+
 	require.NotNil(t, GetManager())
 	require.IsType(t, &filesystemCache{}, GetManager())
 

internal/cache/memory.go

@@ -8,6 +8,9 @@ import (
 
 // NewInMemory returns an in-memory only cache manager
 func NewInMemory(ttl time.Duration) Manager {
+	if ttl <= 0 {
+		return &bypassedCache{}
+	}
 	return &filesystemCache{
 		dir: "",
 		fs:  afero.NewMemMapFs(),