implement pruning for plugins

pkg/skaffold/build/bazel/bazel.go

@@ -115,7 +115,7 @@ func (b *Builder) local(ctx context.Context, out io.Writer, tags tag.ImageTags,
 }
 
 func (b *Builder) Prune(ctx context.Context, out io.Writer) error {
-	// TODO(nkubala): implement
+	// bazel builds directly to the registry, so this is a noop
 	return nil
 }
 

pkg/skaffold/build/plugin/core.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/constants"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/plugin/builders/bazel"
@@ -67,6 +68,10 @@ func Execute() error {
 	err := <-errCh
 
 	if err == cancelError {
+		// there is a race between skaffold's cleanup process and us shutting down the plugin client.
+		// since we are actually using the plugin to perform the image pruning, we need to give skaffold
+		// a small window to call this before we can safely shutdown.
+		time.Sleep(30 * time.Millisecond)
 		hashiplugin.CleanupClients()
 	}
 	if err != nil {

pkg/skaffold/plugin/shared/client.go

@@ -0,0 +1,93 @@
+/*
+Copyright 2019 The Skaffold Authors
+
+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 shared
+
+import (
+	"context"
+	"io"
+	"net/rpc"
+
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/build"
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/build/tag"
+
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/config"
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// BuilderRPC is an implementation of an rpc client
+type BuilderRPC struct {
+	client *rpc.Client
+}
+
+func (b *BuilderRPC) Init(opts *config.SkaffoldOptions, env *latest.ExecutionEnvironment) {
+	// We don't expect a response, so we can just use interface{}
+	var resp interface{}
+	args := InitArgs{
+		Opts: opts,
+		Env:  env,
+	}
+	b.client.Call("Plugin.Init", args, &resp)
+}
+
+func (b *BuilderRPC) DependenciesForArtifact(_ context.Context, artifact *latest.Artifact) ([]string, error) {
+	var resp []string
+	if err := convertPropertiesToBytes([]*latest.Artifact{artifact}); err != nil {
+		return nil, errors.Wrapf(err, "converting properties to bytes")
+	}
+	args := DependencyArgs{artifact}
+	err := b.client.Call("Plugin.DependenciesForArtifact", args, &resp)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+func (b *BuilderRPC) Labels() map[string]string {
+	var resp map[string]string
+	err := b.client.Call("Plugin.Labels", new(interface{}), &resp)
+	if err != nil {
+		// Can't return error, so log it instead
+		logrus.Errorf("Unable to get labels from server: %v", err)
+	}
+	return resp
+}
+
+func (b *BuilderRPC) Build(_ context.Context, _ io.Writer, tags tag.ImageTags, artifacts []*latest.Artifact) ([]build.Artifact, error) {
+	var resp []build.Artifact
+	if err := convertPropertiesToBytes(artifacts); err != nil {
+		return nil, errors.Wrapf(err, "converting properties to bytes")
+	}
+	args := BuildArgs{
+		ImageTags: tags,
+		Artifacts: artifacts,
+	}
+	err := b.client.Call("Plugin.Build", args, &resp)
+	if err != nil {
+		return nil, err
+	}
+	return resp, nil
+}
+
+func (b *BuilderRPC) Prune(ctx context.Context, out io.Writer) error {
+	var resp interface{}
+	if err := b.client.Call("Plugin.Prune", new(interface{}), &resp); err != nil {
+		return err
+	}
+	return nil
+}

pkg/skaffold/plugin/shared/server.go

@@ -18,7 +18,6 @@ package shared
 
 import (
 	"context"
-	"io"
 	"net/rpc"
 	"os"
 
@@ -28,72 +27,9 @@ import (
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
 	plugin "github.com/hashicorp/go-plugin"
 	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
 	yaml "gopkg.in/yaml.v2"
 )
 
-// BuilderRPC is an implementation of an rpc client
-type BuilderRPC struct {
-	client *rpc.Client
-}
-
-func (b *BuilderRPC) Init(opts *config.SkaffoldOptions, env *latest.ExecutionEnvironment) {
-	// We don't expect a response, so we can just use interface{}
-	var resp interface{}
-	args := InitArgs{
-		Opts: opts,
-		Env:  env,
-	}
-	b.client.Call("Plugin.Init", args, &resp)
-}
-
-func (b *BuilderRPC) DependenciesForArtifact(_ context.Context, artifact *latest.Artifact) ([]string, error) {
-	var resp []string
-	if err := convertPropertiesToBytes([]*latest.Artifact{artifact}); err != nil {
-		return nil, errors.Wrapf(err, "converting properties to bytes")
-	}
-	args := DependencyArgs{artifact}
-	err := b.client.Call("Plugin.DependenciesForArtifact", args, &resp)
-	if err != nil {
-		return nil, err
-	}
-	return resp, nil
-}
-
-func (b *BuilderRPC) Labels() map[string]string {
-	var resp map[string]string
-	err := b.client.Call("Plugin.Labels", new(interface{}), &resp)
-	if err != nil {
-		// Can't return error, so log it instead
-		logrus.Errorf("Unable to get labels from server: %v", err)
-	}
-	return resp
-}
-
-func (b *BuilderRPC) Build(_ context.Context, _ io.Writer, tags tag.ImageTags, artifacts []*latest.Artifact) ([]build.Artifact, error) {
-	var resp []build.Artifact
-	if err := convertPropertiesToBytes(artifacts); err != nil {
-		return nil, errors.Wrapf(err, "converting properties to bytes")
-	}
-	args := BuildArgs{
-		ImageTags: tags,
-		Artifacts: artifacts,
-	}
-	err := b.client.Call("Plugin.Build", args, &resp)
-	if err != nil {
-		return nil, err
-	}
-	return resp, nil
-}
-
-func (b *BuilderRPC) Prune(_ context.Context, _ io.Writer) error {
-	var resp error
-	if err := b.client.Call("Plugin.Prune", new(interface{}), &resp); err != nil {
-		return err
-	}
-	return resp
-}
-
 func convertPropertiesToBytes(artifacts []*latest.Artifact) error {
 	for _, a := range artifacts {
 		if a.BuilderPlugin.Properties == nil {
@@ -120,7 +56,7 @@ func (s *BuilderRPCServer) Init(args InitArgs, resp *interface{}) error {
 	return nil
 }
 
-func (s *BuilderRPCServer) Labels(args interface{}, resp *map[string]string) error {
+func (s *BuilderRPCServer) Labels(_ interface{}, resp *map[string]string) error {
 	*resp = s.Impl.Labels()
 	return nil
 }
@@ -134,6 +70,10 @@ func (s *BuilderRPCServer) Build(b BuildArgs, resp *[]build.Artifact) error {
 	return nil
 }
 
+func (s *BuilderRPCServer) Prune(args interface{}, resp *interface{}) error {
+	return s.Impl.Prune(context.Background(), os.Stdout)
+}
+
 func (s *BuilderRPCServer) DependenciesForArtifact(d DependencyArgs, resp *[]string) error {
 	dependencies, err := s.Impl.DependenciesForArtifact(context.Background(), d.Artifact)
 	if err != nil {