cache: Add support for bind cache

acceptance/acceptance_test.go

@@ -1797,6 +1797,33 @@ func testAcceptance(
 						})
 					})
 
+					when("--cache with options for build cache as bind", func() {
+						var bindCacheDir, cacheFlags string
+						it.Before(func() {
+							h.SkipIf(t, !pack.SupportsFeature(invoke.Cache), "")
+							cacheBindName := fmt.Sprintf("%s-bind", repoName)
+							bindCacheDir, err := ioutil.TempDir("", cacheBindName)
+							assert.Nil(err)
+							cacheFlags = fmt.Sprintf("type=build;format=bind;source=%s", bindCacheDir)
+						})
+
+						it("creates image and cache image on the registry", func() {
+							buildArgs := []string{
+								repoName,
+								"-p", filepath.Join("testdata", "mock_app"),
+								"--cache",
+								cacheFlags,
+							}
+
+							output := pack.RunSuccessfully("build", buildArgs...)
+							assertions.NewOutputAssertionManager(t, output).ReportsSuccessfulImageBuild(repoName)
+
+							t.Log("checking that bind mount has cache contents")
+							assert.FileExists(fmt.Sprintf("%s/committed", bindCacheDir))
+							defer os.RemoveAll(bindCacheDir)
+						})
+					})
+
 					when("ctrl+c", func() {
 						it("stops the execution", func() {
 							var buf = new(bytes.Buffer)

internal/build/lifecycle_execution.go

@@ -135,10 +135,16 @@ func (l *LifecycleExecution) Run(ctx context.Context, phaseFactoryCreator PhaseF
 		}
 		buildCache = cache.NewImageCache(cacheImage, l.docker)
 	} else {
-		buildCache = cache.NewVolumeCache(l.opts.Image, l.opts.Cache.Build, "build", l.docker)
+		switch l.opts.Cache.Build.Format {
+		case cache.CacheVolume:
+			buildCache = cache.NewVolumeCache(l.opts.Image, l.opts.Cache.Build, "build", l.docker)
+			l.logger.Debugf("Using build cache volume %s", style.Symbol(buildCache.Name()))
+		case cache.CacheBind:
+			buildCache = cache.NewBindCache(l.opts.Cache.Build, l.docker)
+			l.logger.Debugf("Using build cache dir %s", style.Symbol(buildCache.Name()))
+		}
 	}
 
-	l.logger.Debugf("Using build cache volume %s", style.Symbol(buildCache.Name()))
 	if l.opts.ClearCache {
 		if err := buildCache.Clear(ctx); err != nil {
 			return errors.Wrap(err, "clearing build cache")
@@ -251,7 +257,7 @@ func (l *LifecycleExecution) Create(ctx context.Context, publish bool, dockerHos
 	case cache.Image:
 		flags = append(flags, "-cache-image", buildCache.Name())
 		cacheOpts = WithBinds(volumes...)
-	case cache.Volume:
+	case cache.Volume, cache.Bind:
 		cacheOpts = WithBinds(append(volumes, fmt.Sprintf("%s:%s", buildCache.Name(), l.mountPaths.cacheDir()))...)
 	}
 

internal/cache/bind_cache.go

@@ -0,0 +1,36 @@
+package cache
+
+import (
+	"context"
+	"os"
+
+	"github.com/docker/docker/client"
+)
+
+type BindCache struct {
+	docker client.CommonAPIClient
+	bind   string
+}
+
+func NewBindCache(cacheType CacheInfo, dockerClient client.CommonAPIClient) *BindCache {
+	return &BindCache{
+		bind:   cacheType.Source,
+		docker: dockerClient,
+	}
+}
+
+func (c *BindCache) Name() string {
+	return c.bind
+}
+
+func (c *BindCache) Clear(ctx context.Context) error {
+	err := os.RemoveAll(c.bind)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (c *BindCache) Type() Type {
+	return Bind
+}

internal/cache/cache_opts.go

@@ -3,6 +3,7 @@ package cache
 import (
 	"encoding/csv"
 	"fmt"
+	"path/filepath"
 	"strings"
 
 	"github.com/pkg/errors"
@@ -13,6 +14,7 @@ type CacheInfo struct {
 	Format Format
 	Source string
 }
+
 type CacheOpts struct {
 	Build  CacheInfo
 	Launch CacheInfo
@@ -21,6 +23,7 @@ type CacheOpts struct {
 const (
 	CacheVolume Format = iota
 	CacheImage
+	CacheBind
 )
 
 func (f Format) String() string {
@@ -29,6 +32,20 @@ func (f Format) String() string {
 		return "image"
 	case CacheVolume:
 		return "volume"
+	case CacheBind:
+		return "bind"
+	}
+	return ""
+}
+
+func (c *CacheInfo) SourceName() string {
+	switch c.Format {
+	case CacheImage:
+		fallthrough
+	case CacheVolume:
+		return "name"
+	case CacheBind:
+		return "source"
 	}
 	return ""
 }
@@ -76,15 +93,19 @@ func (c *CacheOpts) Set(value string) error {
 				cache.Format = CacheImage
 			case "volume":
 				cache.Format = CacheVolume
+			case "bind":
+				cache.Format = CacheBind
 			default:
 				return errors.Errorf("invalid cache format '%s'", value)
 			}
 		case "name":
 			cache.Source = value
+		case "source":
+			cache.Source = value
 		}
 	}
 
-	err = populateMissing(c)
+	err = sanitize(c)
 	if err != nil {
 		return err
 	}
@@ -93,18 +114,47 @@ func (c *CacheOpts) Set(value string) error {
 
 func (c *CacheOpts) String() string {
 	var cacheFlag string
-	cacheFlag = fmt.Sprintf("type=build;format=%s;name=%s;", c.Build.Format.String(), c.Build.Source)
-	cacheFlag += fmt.Sprintf("type=launch;format=%s;name=%s;", c.Launch.Format.String(), c.Launch.Source)
+	cacheFlag = fmt.Sprintf("type=build;format=%s;", c.Build.Format.String())
+	if c.Build.Source != "" {
+		cacheFlag += fmt.Sprintf("%s=%s;", c.Build.SourceName(), c.Build.Source)
+	}
+
+	cacheFlag += fmt.Sprintf("type=launch;format=%s;", c.Launch.Format.String())
+	if c.Launch.Source != "" {
+		cacheFlag += fmt.Sprintf("%s=%s;", c.Launch.SourceName(), c.Launch.Source)
+	}
+
 	return cacheFlag
 }
 
 func (c *CacheOpts) Type() string {
 	return "cache"
 }
 
-func populateMissing(c *CacheOpts) error {
-	if (c.Build.Source == "" && c.Build.Format == CacheImage) || (c.Launch.Source == "" && c.Launch.Format == CacheImage) {
-		return errors.Errorf("cache 'name' is required")
+func sanitize(c *CacheOpts) error {
+	for _, v := range []CacheInfo{c.Build, c.Launch} {
+		// volume cache name can be auto-generated
+		if v.Format != CacheVolume && v.Source == "" {
+			return errors.Errorf("cache '%s' is required", v.SourceName())
+		}
+	}
+
+	if c.Build.Format == CacheBind || c.Launch.Format == CacheBind {
+		var (
+			resolvedPath string
+			err          error
+		)
+		if c.Build.Format == CacheBind {
+			if resolvedPath, err = filepath.Abs(c.Build.Source); err != nil {
+				return errors.Wrap(err, "resolve absolute path")
+			}
+			c.Build.Source = filepath.Join(resolvedPath, "build-cache")
+		} else {
+			if resolvedPath, err = filepath.Abs(c.Launch.Source); err != nil {
+				return errors.Wrap(err, "resolve absolute path")
+			}
+			c.Launch.Source = filepath.Join(resolvedPath, "launch-cache")
+		}
 	}
 	return nil
 }