Rework cache key generation a bit. (#375)

* Rework cache key generation a bit.

Cache keys are now based on the previous commands, rather than the previous state
of the filesystem.

* Refactor command interface a bit, only cache the context for commands that use it.

pkg/commands/add.go

@@ -29,6 +29,7 @@ import (
 )
 
 type AddCommand struct {
+	BaseCommand
 	cmd           *instructions.AddCommand
 	buildcontext  string
 	snapshotFiles []string
@@ -110,7 +111,6 @@ func (a *AddCommand) String() string {
 	return a.cmd.String()
 }
 
-// CacheCommand returns false since this command shouldn't be cached
-func (a *AddCommand) CacheCommand() bool {
-	return false
+func (a *AddCommand) UsesContext() bool {
+	return true
 }

pkg/commands/arg.go

@@ -24,6 +24,7 @@ import (
 )
 
 type ArgCommand struct {
+	BaseCommand
 	cmd *instructions.ArgCommand
 }
 
@@ -46,17 +47,7 @@ func (r *ArgCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this command only touches metadata.
-func (r *ArgCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (r *ArgCommand) String() string {
 	return r.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (r *ArgCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/base_command.go

@@ -0,0 +1,34 @@
+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package commands
+
+type BaseCommand struct {
+	cache       bool
+	usesContext bool
+}
+
+func (b *BaseCommand) CacheCommand() bool {
+	return b.cache
+}
+
+func (b *BaseCommand) UsesContext() bool {
+	return b.usesContext
+}
+
+func (b *BaseCommand) FilesToSnapshot() []string {
+	return []string{}
+}

pkg/commands/cmd.go

@@ -26,6 +26,7 @@ import (
 )
 
 type CmdCommand struct {
+	BaseCommand
 	cmd *instructions.CmdCommand
 }
 
@@ -52,17 +53,7 @@ func (c *CmdCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this is a metadata command
-func (c *CmdCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (c *CmdCommand) String() string {
 	return c.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (c *CmdCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/cmd_test.go

@@ -48,7 +48,7 @@ func TestExecuteCmd(t *testing.T) {
 
 	for _, test := range cmdTests {
 		cmd := CmdCommand{
-			&instructions.CmdCommand{
+			cmd: &instructions.CmdCommand{
 				ShellDependantCmdLine: instructions.ShellDependantCmdLine{
 					PrependShell: test.prependShell,
 					CmdLine:      test.cmdLine,

pkg/commands/commands.go

@@ -37,6 +37,9 @@ type DockerCommand interface {
 	// Return true if this command should be true
 	// Currently only true for RUN
 	CacheCommand() bool
+
+	// Return true if this command depends on the build context.
+	UsesContext() bool
 }
 
 func GetCommand(cmd instructions.Command, buildcontext string) (DockerCommand, error) {

pkg/commands/copy.go

@@ -29,6 +29,7 @@ import (
 )
 
 type CopyCommand struct {
+	BaseCommand
 	cmd           *instructions.CopyCommand
 	buildcontext  string
 	snapshotFiles []string
@@ -103,7 +104,6 @@ func (c *CopyCommand) String() string {
 	return c.cmd.String()
 }
 
-// CacheCommand returns true since this command should be cached
-func (c *CopyCommand) CacheCommand() bool {
-	return false
+func (c *CopyCommand) UsesContext() bool {
+	return true
 }

pkg/commands/entrypoint.go

@@ -26,6 +26,7 @@ import (
 )
 
 type EntrypointCommand struct {
+	BaseCommand
 	cmd *instructions.EntrypointCommand
 }
 
@@ -50,17 +51,7 @@ func (e *EntrypointCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerf
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this is a metadata command
-func (e *EntrypointCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (e *EntrypointCommand) String() string {
 	return e.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (e *EntrypointCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/entrypoint_test.go

@@ -48,7 +48,7 @@ func TestEntrypointExecuteCmd(t *testing.T) {
 
 	for _, test := range entrypointTests {
 		cmd := EntrypointCommand{
-			&instructions.EntrypointCommand{
+			cmd: &instructions.EntrypointCommand{
 				ShellDependantCmdLine: instructions.ShellDependantCmdLine{
 					PrependShell: test.prependShell,
 					CmdLine:      test.cmdLine,

pkg/commands/env.go

@@ -25,6 +25,7 @@ import (
 )
 
 type EnvCommand struct {
+	BaseCommand
 	cmd *instructions.EnvCommand
 }
 
@@ -34,17 +35,7 @@ func (e *EnvCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 	return util.UpdateConfigEnv(newEnvs, config, replacementEnvs)
 }
 
-// We know that no files have changed, so return an empty array
-func (e *EnvCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (e *EnvCommand) String() string {
 	return e.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (e *EnvCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/env_test.go

@@ -33,7 +33,7 @@ func Test_EnvExecute(t *testing.T) {
 	}
 
 	envCmd := &EnvCommand{
-		&instructions.EnvCommand{
+		cmd: &instructions.EnvCommand{
 			Env: []instructions.KeyValuePair{
 				{
 					Key:   "path",

pkg/commands/expose.go

@@ -29,6 +29,7 @@ import (
 )
 
 type ExposeCommand struct {
+	BaseCommand
 	cmd *instructions.ExposeCommand
 }
 
@@ -72,15 +73,6 @@ func validProtocol(protocol string) bool {
 	return false
 }
 
-func (r *ExposeCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 func (r *ExposeCommand) String() string {
 	return r.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (r *ExposeCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/expose_test.go

@@ -48,7 +48,7 @@ func TestUpdateExposedPorts(t *testing.T) {
 	}
 
 	exposeCmd := &ExposeCommand{
-		&instructions.ExposeCommand{
+		cmd: &instructions.ExposeCommand{
 			Ports: ports,
 		},
 	}
@@ -77,7 +77,7 @@ func TestInvalidProtocol(t *testing.T) {
 	}
 
 	exposeCmd := &ExposeCommand{
-		&instructions.ExposeCommand{
+		cmd: &instructions.ExposeCommand{
 			Ports: ports,
 		},
 	}

pkg/commands/healthcheck.go

@@ -23,6 +23,7 @@ import (
 )
 
 type HealthCheckCommand struct {
+	BaseCommand
 	cmd *instructions.HealthCheckCommand
 }
 
@@ -34,17 +35,7 @@ func (h *HealthCheckCommand) ExecuteCommand(config *v1.Config, buildArgs *docker
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this is a metadata command
-func (h *HealthCheckCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (h *HealthCheckCommand) String() string {
 	return h.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (h *HealthCheckCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/label.go

@@ -26,6 +26,7 @@ import (
 )
 
 type LabelCommand struct {
+	BaseCommand
 	cmd *instructions.LabelCommand
 }
 
@@ -64,17 +65,7 @@ func updateLabels(labels []instructions.KeyValuePair, config *v1.Config, buildAr
 
 }
 
-// No files have changed, this command only touches metadata.
-func (r *LabelCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (r *LabelCommand) String() string {
 	return r.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (r *LabelCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/onbuild.go

@@ -24,6 +24,7 @@ import (
 )
 
 type OnBuildCommand struct {
+	BaseCommand
 	cmd *instructions.OnbuildCommand
 }
 
@@ -39,17 +40,7 @@ func (o *OnBuildCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile
 	return nil
 }
 
-// FilesToSnapshot returns that no files have changed, this command only touches metadata.
-func (o *OnBuildCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (o *OnBuildCommand) String() string {
 	return o.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (o *OnBuildCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/onbuild_test.go

@@ -60,7 +60,7 @@ func TestExecuteOnbuild(t *testing.T) {
 		}
 
 		onbuildCmd := &OnBuildCommand{
-			&instructions.OnbuildCommand{
+			cmd: &instructions.OnbuildCommand{
 				Expression: test.expression,
 			},
 		}

pkg/commands/run.go

@@ -35,6 +35,7 @@ import (
 )
 
 type RunCommand struct {
+	BaseCommand
 	cmd *instructions.RunCommand
 }
 
@@ -142,17 +143,15 @@ func addDefaultHOME(u string, envs []string) []string {
 	return append(envs, home)
 }
 
-// FilesToSnapshot returns nil for this command because we don't know which files
-// have changed, so we snapshot the entire system.
-func (r *RunCommand) FilesToSnapshot() []string {
-	return nil
-}
-
 // String returns some information about the command for the image config
 func (r *RunCommand) String() string {
 	return r.cmd.String()
 }
 
+func (r *RunCommand) FilesToSnapshot() []string {
+	return nil
+}
+
 // CacheCommand returns true since this command should be cached
 func (r *RunCommand) CacheCommand() bool {
 	return true

pkg/commands/shell.go

@@ -23,6 +23,7 @@ import (
 )
 
 type ShellCommand struct {
+	BaseCommand
 	cmd *instructions.ShellCommand
 }
 
@@ -32,17 +33,7 @@ func (s *ShellCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.B
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this is a metadata command
-func (s *ShellCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (s *ShellCommand) String() string {
 	return s.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (s *ShellCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/shell_test.go

@@ -45,7 +45,7 @@ func TestShellExecuteCmd(t *testing.T) {
 
 	for _, test := range shellTests {
 		cmd := ShellCommand{
-			&instructions.ShellCommand{
+			cmd: &instructions.ShellCommand{
 				Shell: test.cmdLine,
 			},
 		}

pkg/commands/stopsignal.go

@@ -26,6 +26,7 @@ import (
 )
 
 type StopSignalCommand struct {
+	BaseCommand
 	cmd *instructions.StopSignalCommand
 }
 
@@ -52,17 +53,7 @@ func (s *StopSignalCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerf
 	return nil
 }
 
-// FilesToSnapshot returns an empty array since this is a metadata command
-func (s *StopSignalCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 // String returns some information about the command for the image config history
 func (s *StopSignalCommand) String() string {
 	return s.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (s *StopSignalCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/stopsignal_test.go

@@ -51,7 +51,7 @@ func TestStopsignalExecuteCmd(t *testing.T) {
 
 	for _, test := range stopsignalTests {
 		cmd := StopSignalCommand{
-			&instructions.StopSignalCommand{
+			cmd: &instructions.StopSignalCommand{
 				Signal: test.signal,
 			},
 		}

pkg/commands/user.go

@@ -27,6 +27,7 @@ import (
 )
 
 type UserCommand struct {
+	BaseCommand
 	cmd *instructions.UserCommand
 }
 
@@ -59,15 +60,6 @@ func (r *UserCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bu
 	return nil
 }
 
-func (r *UserCommand) FilesToSnapshot() []string {
-	return []string{}
-}
-
 func (r *UserCommand) String() string {
 	return r.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (r *UserCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/user_test.go

@@ -91,7 +91,7 @@ func TestUpdateUser(t *testing.T) {
 			},
 		}
 		cmd := UserCommand{
-			&instructions.UserCommand{
+			cmd: &instructions.UserCommand{
 				User: test.user,
 			},
 		}

pkg/commands/volume.go

@@ -29,6 +29,7 @@ import (
 )
 
 type VolumeCommand struct {
+	BaseCommand
 	cmd           *instructions.VolumeCommand
 	snapshotFiles []string
 }
@@ -74,8 +75,3 @@ func (v *VolumeCommand) FilesToSnapshot() []string {
 func (v *VolumeCommand) String() string {
 	return v.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (v *VolumeCommand) CacheCommand() bool {
-	return false
-}

pkg/commands/workdir.go

@@ -29,6 +29,7 @@ import (
 )
 
 type WorkdirCommand struct {
+	BaseCommand
 	cmd           *instructions.WorkdirCommand
 	snapshotFiles []string
 }
@@ -66,8 +67,3 @@ func (w *WorkdirCommand) FilesToSnapshot() []string {
 func (w *WorkdirCommand) String() string {
 	return w.cmd.String()
 }
-
-// CacheCommand returns false since this command shouldn't be cached
-func (w *WorkdirCommand) CacheCommand() bool {
-	return false
-}

pkg/executor/build.go

@@ -18,7 +18,6 @@ package executor
 
 import (
 	"bytes"
-	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -85,23 +84,6 @@ func newStageBuilder(opts *config.KanikoOptions, stage config.KanikoStage) (*sta
 	}, nil
 }
 
-// key will return a string representation of the build at the cmd
-func (s *stageBuilder) key(cmd string) (string, error) {
-	fsKey, err := s.snapshotter.Key()
-	if err != nil {
-		return "", err
-	}
-	c := bytes.NewBuffer([]byte{})
-	enc := json.NewEncoder(c)
-	enc.Encode(s.cf)
-	cf, err := util.SHA256(c)
-	if err != nil {
-		return "", err
-	}
-	logrus.Debugf("%s\n%s\n%s\n%s\n", s.baseImageDigest, fsKey, cf, cmd)
-	return util.SHA256(bytes.NewReader([]byte(s.baseImageDigest + fsKey + cf + cmd)))
-}
-
 // extractCachedLayer will extract the cached layer and append it to the config file
 func (s *stageBuilder) extractCachedLayer(layer v1.Image, createdBy string) error {
 	logrus.Infof("Found cached layer, extracting to filesystem")
@@ -139,6 +121,15 @@ func (s *stageBuilder) build(opts *config.KanikoOptions) error {
 		return err
 	}
 	var volumes []string
+
+	// Set the initial cache key to be the base image digest, the build args and the SrcContext.
+	compositeKey := NewCompositeCache(s.baseImageDigest)
+	contextHash, err := HashDir(opts.SrcContext)
+	if err != nil {
+		return err
+	}
+	compositeKey.AddKey(opts.BuildArgs...)
+
 	args := dockerfile.NewBuildArgs(opts.BuildArgs)
 	for index, cmd := range s.stage.Commands {
 		finalCmd := index == len(s.stage.Commands)-1
@@ -149,13 +140,21 @@ func (s *stageBuilder) build(opts *config.KanikoOptions) error {
 		if command == nil {
 			continue
 		}
-		logrus.Info(command.String())
-		cacheKey, err := s.key(command.String())
-		if err != nil {
-			return errors.Wrap(err, "getting key")
+
+		// Add the next command to the cache key.
+		compositeKey.AddKey(command.String())
+		if command.UsesContext() {
+			compositeKey.AddKey(contextHash)
 		}
+		logrus.Info(command.String())
+
+		ck, err := compositeKey.Hash()
+		if err != nil {
+			return err
+		}
+
 		if command.CacheCommand() && opts.Cache {
-			image, err := cache.RetrieveLayer(opts, cacheKey)
+			image, err := cache.RetrieveLayer(opts, ck)
 			if err == nil {
 				if err := s.extractCachedLayer(image, command.String()); err != nil {
 					return errors.Wrap(err, "extracting cached layer")
@@ -222,7 +221,7 @@ func (s *stageBuilder) build(opts *config.KanikoOptions) error {
 		}
 		// Push layer to cache now along with new config file
 		if command.CacheCommand() && opts.Cache {
-			if err := pushLayerToCache(opts, cacheKey, layer, command.String()); err != nil {
+			if err := pushLayerToCache(opts, ck, layer, command.String()); err != nil {
 				return err
 			}
 		}

pkg/executor/composite_cache.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2018 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package executor
+
+import (
+	"crypto/sha256"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/GoogleContainerTools/kaniko/pkg/util"
+)
+
+// NewCompositeCache returns an initialized composite cache object.
+func NewCompositeCache(initial ...string) *CompositeCache {
+	c := CompositeCache{
+		keys: initial,
+	}
+	return &c
+}
+
+// CompositeCache is a type that generates a cache key from a series of keys.
+type CompositeCache struct {
+	keys []string
+}
+
+// AddKey adds the specified key to the sequence.
+func (s *CompositeCache) AddKey(k ...string) {
+	s.keys = append(s.keys, k...)
+}
+
+// Key returns the human readable composite key as a string.
+func (s *CompositeCache) Key() string {
+	return strings.Join(s.keys, "-")
+}
+
+// Hash returns the composite key in a string SHA256 format.
+func (s *CompositeCache) Hash() (string, error) {
+	return util.SHA256(strings.NewReader(s.Key()))
+}
+
+// HashDir returns a hash of the directory.
+func HashDir(p string) (string, error) {
+	sha := sha256.New()
+	if err := filepath.Walk(p, func(path string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		fileHash, err := util.CacheHasher()(path)
+		if err != nil {
+			return err
+		}
+		if _, err := sha.Write([]byte(fileHash)); err != nil {
+			return err
+		}
+		return nil
+	}); err != nil {
+		return "", err
+	}
+
+	return string(sha.Sum(nil)), nil
+}