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
 }
 
@@ -142,12 +143,6 @@ 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()

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,
 			},
 		}