Add a script to run the executor in a Docker container locally.

Also force GOOS=linux for the executor. It doesn't make sense to cross compile that.

Makefile

@@ -35,7 +35,7 @@ EXECUTOR_PACKAGE = $(REPOPATH)/executor
 KBUILD_PACKAGE = $(REPOPATH)/kbuild
 
 out/executor: $(GO_FILES)
-	GOOS=$* GOARCH=$(GOARCH) CGO_ENABLED=0 go build -ldflags $(GO_LDFLAGS) -tags $(GO_BUILD_TAGS) -o $@ $(EXECUTOR_PACKAGE)
+	GOARCH=$(GOARCH) GOOS=linux CGO_ENABLED=0 go build -ldflags $(GO_LDFLAGS) -tags $(GO_BUILD_TAGS) -o $@ $(EXECUTOR_PACKAGE)
 
 
 out/kbuild: $(GO_FILES)

run_in_docker.sh

@@ -0,0 +1,35 @@
+# 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.
+
+#!/bin/bash
+set -e
+
+if [ $# -ne 2 ];
+    then echo "Usage: run_in_docker.sh <context directory> <image tag>"
+fi
+
+
+context=$1
+tag=$2
+
+if [[ ! -e $HOME/.config/gcloud/application_default_credentials.json ]]; then
+    echo "Application Default Credentials do not exist. Run [gcloud auth application-default login] to configure them"
+    exit 1
+fi
+
+docker run \
+    -v $HOME/.config/gcloud:/root/.config/gcloud \
+    -v ${context}:/workspace \
+    gcr.io/kbuild-project/executor:latest \
+    /kbuild/executor -d ${tag}