refactor build tooling

- adds required `GCLOUD_SDK_VERSION` `--build-arg` to `Dockerfile`
- removes `Dockerfile.1.10`, `Dockerfile.1.11` (can now be customized via `GCLOUD_SDK_VERSION` build arg)
- removes `bin/dist`; replaced with `make`-based implementation
- adds several misc config / rc files
- updates `README`, `DOCS.md` to reflect changes, address linting

.dockerignore

@@ -0,0 +1,5 @@
+.git
+.github
+.vscode
+local-example
+

.drone.yml

@@ -7,14 +7,15 @@ build_config: &build_config
   image: golang:1
   environment:
     - GO111MODULE=on
-    - GOPROXY=https://proxy.golang.org 
+    - GOPROXY=https://proxy.golang.org
     - CGO_ENABLED=0
   commands:
     - go build -a -ldflags "-X main.version=${DRONE_TAG:-other} -X main.rev=${DRONE_COMMIT}"
 
 publish_config: &publish_config
   image: plugins/docker
   repo: nytimes/drone-gke
+  dockerfile: Dockerfile
   secrets:
     - docker_username
     - docker_password
@@ -24,7 +25,7 @@ pipeline:
     image: golang:1
     environment:
       - GO111MODULE=on
-      - GOPROXY=https://proxy.golang.org 
+      - GOPROXY=https://proxy.golang.org
       - CGO_ENABLED=0
     commands:
       - go mod download
@@ -45,6 +46,8 @@ pipeline:
 
   publish_develop:
     <<: *publish_config
+    build_args:
+    - CLOUD_SDK_VERSION=alpine
     tag:
       - "develop"
     when:
@@ -53,19 +56,23 @@ pipeline:
 
   publish_latest:
     <<: *publish_config
+    build_args:
+    - CLOUD_SDK_VERSION=alpine
     auto_tag: true
 
   publish_1_10:
     <<: *publish_config
+    build_args:
+    - CLOUD_SDK_VERSION=217.0.0
     auto_tag: true
     auto_tag_suffix: "k8s-1.10"
-    dockerfile: Dockerfile.1.10
 
   publish_1_11:
     <<: *publish_config
+    build_args:
+    - CLOUD_SDK_VERSION=241.0.0
     auto_tag: true
     auto_tag_suffix: "k8s-1.11"
-    dockerfile: Dockerfile.1.11
 
   slack:
     image: plugins/slack

.editorconfig

@@ -0,0 +1,21 @@
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
+
+[*.go]
+indent_style = tab
+
+[{go.mod,go.sum}]
+indent_style = tab
+
+[Makefile]
+indent_style = tab

.gitignore

@@ -1 +1,2 @@
 /drone-gke
+.vscode

DOCS.md

@@ -1,3 +1,5 @@
+# drone-gke Usage
+
 Use this plugin to deploy Docker images to [Google Container Engine (GKE)][gke].
 
 [gke]: https://cloud.google.com/container-engine/
@@ -47,7 +49,7 @@ Simply copy the contents of the JSON credentials file and paste it directly in t
 
 #### CLI
 
-```
+```sh
 drone secret add \
   --event push \
   --event pull_request \
@@ -78,19 +80,17 @@ Kubernetes expects secrets to be base64 encoded, `drone-gke` does that for you.
 
 These variables are always available to reference in any manifest, and cannot be overwritten by `vars` or `secrets`:
 
-```
----START VARIABLES AVAILABLE FOR ALL TEMPLATES---
+```json
 {
-	"BRANCH": "master",
-	"BUILD_NUMBER": "12",
-	"COMMIT": "4923x0c3380413ec9288e3c0bfbf534b0f18fed1",
-	"TAG": "",
-	"cluster": "my-gke-cluster",
-	"namespace": "",
-	"project": "my-gcp-proj",
-	"zone": "us-east1-a"
+  "BRANCH": "master",
+  "BUILD_NUMBER": "12",
+  "COMMIT": "4923x0c3380413ec9288e3c0bfbf534b0f18fed1",
+  "TAG": "",
+  "cluster": "my-gke-cluster",
+  "namespace": "",
+  "project": "my-gcp-proj",
+  "zone": "us-east1-a"
 }
----END VARIABLES AVAILABLE FOR ALL TEMPLATES---
 ```
 
 ## Expanding environment variables

Dockerfile

@@ -1,14 +1,12 @@
-# latest kubectl in the SDK
-# https://cloud.google.com/sdk/docs/release-notes
-FROM google/cloud-sdk:alpine
-
-# Install kubectl
-RUN gcloud components install kubectl && \
-    rm -rf ./google-cloud-sdk/.install
+# see https://hub.docker.com/r/google/cloud-sdk/tags for available tags / versions
+ARG GCLOUD_SDK_VERSION
 
+FROM google/cloud-sdk:${GCLOUD_SDK_VERSION} AS cloud-sdk
 ENV CLOUDSDK_CONTAINER_USE_APPLICATION_DEFAULT_CREDENTIALS=true
+ENV CLOUDSDK_CORE_DISABLE_PROMPTS=1
+ADD bin/install-kubectl /usr/local/bin/
+RUN install-kubectl && rm -f /usr/local/bin/install-kubectl
 
-# Add the Drone plugin
-ADD drone-gke /bin/
-
-ENTRYPOINT ["/bin/drone-gke"]
+FROM cloud-sdk
+ADD drone-gke /usr/local/bin/
+ENTRYPOINT ["drone-gke"]

Makefile

@@ -0,0 +1,191 @@
+# executables
+docker := $(shell which docker) --log-level error
+gcloud := $(shell which gcloud) --quiet --verbosity=error
+git := $(shell which git)
+go := $(shell which go)
+kubectl := $(shell which kubectl)
+
+# plugin's binary options
+binary_name = drone-gke
+
+# git options
+git_default_branch = $(shell cat $(CURDIR)/.git/refs/remotes/origin/HEAD | cut -d ' ' -f 2 | cut -d '/' -f 4)
+git_current_branch = $(shell $(git) rev-parse --abbrev-ref HEAD)
+git_current_revision = $(shell $(git) rev-parse --short HEAD)
+
+# plugin's docker options
+docker_default_repo_name = nytimes
+docker_image_name = drone-gke
+docker_default_tag = latest
+ifneq ($(git_current_branch), $(git_default_branch))
+	docker_default_tag = $(git_current_branch)
+endif
+docker_default_file = $(CURDIR)/Dockerfile
+docker_default_build_context = $(CURDIR)
+
+# gcloud SDK options
+gcloud_sdk_image_name = google/cloud-sdk
+gcloud_default_sdk_version = alpine
+
+# print usage (default target)
+usage :
+	@echo "Usage:"
+	@echo ""
+	@echo "  \$$ make check               # run tests for required software"
+	@echo "  \$$ make clean               # delete plugin binary, docker image"
+	@echo "  \$$ make dist                # build and push plugin docker image"
+	@echo "  \$$ make docker-image        # build plugin docker image"
+	@echo "  \$$ make docker-release      # push plugin docker image"
+	@echo "  \$$ make docker-run-local    # run docker container using local-example"
+	@echo "  \$$ make $(binary_name)           # build plugin binary"
+	@exit 0
+
+.PHONY : usage
+
+# check that docker is installed
+check-docker :
+ifneq (0,$(shell command -v $(docker) 2>&1 >/dev/null ; echo $$?))
+	$(error "docker not installed")
+else
+	@exit 0
+endif
+
+.PHONY : check-docker
+
+# check that gcloud is installed
+check-gcloud :
+ifneq (0,$(shell command -v $(gcloud) 2>&1 >/dev/null ; echo $$?))
+	$(error "gcloud not installed")
+else
+	@exit 0
+endif
+
+.PHONY : check-gcloud
+
+# check that git is installed
+check-git :
+ifneq (0,$(shell command -v $(git) 2>&1 >/dev/null ; echo $$?))
+	$(error "git not installed")
+else
+	@exit 0
+endif
+
+.PHONY : check-git
+
+# check that go is installed
+check-go :
+ifneq (0,$(shell command -v $(go) 2>&1 >/dev/null ; echo $$?))
+	$(error "go not installed")
+else
+	@exit 0
+endif
+
+.PHONY : check-go
+
+# check that kubectl is installed
+check-kubectl :
+ifneq (0,$(shell command -v $(kubectl) 2>&1 >/dev/null ; echo $$?))
+	$(error "kubectl not installed")
+else
+	@exit 0
+endif
+
+.PHONY : check-kubectl
+
+# check that all required executables are installed
+check : check-docker check-gcloud check-git check-go check-kubectl
+
+.PHONY : check
+
+# clean configuration
+clean : export docker_repo_name ?= $(docker_default_repo_name)
+clean : export docker_tag ?= $(docker_default_tag)
+
+# delete binary, docker image
+clean :
+	@rm -f $(binary_name)
+	@$(docker) rmi --force $(docker_repo_name)/$(docker_image_name):$(docker_tag) 2>/dev/null
+
+.PHONY : clean
+
+# compilation configuration
+$(binary_name) : export CGO_ENABLED ?= 0
+$(binary_name) : export GO111MODULE ?= on
+$(binary_name) : export GOARCH ?= amd64
+$(binary_name) : export GOOS ?= linux
+$(binary_name) : export GOPROXY ?= https://proxy.golang.org
+$(binary_name) : export revision ?= $(git_current_revision)
+
+# compile binary
+$(binary_name) : main.go exec.go go.sum
+	@$(go) build -a -ldflags "-X main.rev=$(revision)"
+
+# docker build configuration
+docker-image : export docker_build_context ?= $(docker_default_build_context)
+docker-image : export docker_file ?= $(docker_default_file)
+docker-image : export docker_repo_name ?= $(docker_default_repo_name)
+docker-image : export docker_tag ?= $(docker_default_tag)
+docker-image : export gcloud_sdk_version ?= $(gcloud_default_sdk_version)
+
+# build docker image
+docker-image : $(binary_name) $(docker_file)
+	@$(docker) build \
+		--build-arg GCLOUD_SDK_VERSION=$(gcloud_sdk_version) \
+		--tag $(docker_repo_name)/$(docker_image_name):$(docker_tag) \
+		--file $(docker_file) $(docker_build_context)
+
+.PHONY : docker-image
+
+# docker push configuration
+docker-release : export docker_repo_name ?= $(docker_default_repo_name)
+docker-release : export docker_tag ?= $(docker_default_tag)
+
+# push docker image
+docker-release :
+	@$(docker) push $(docker_repo_name)/$(docker_image_name):$(docker_tag)
+
+.PHONY : docker-release
+
+# compile binary, build and push docker image
+dist : docker-image docker-release
+
+# local docker run configuration
+docker-run-local : export CONFIG_HOME ?= $(CURDIR)/local-example
+docker-run-local : export GOOGLE_APPLICATION_CREDENTIALS ?= xxx
+docker-run-local : export PLUGIN_CLUSTER ?= yyy
+docker-run-local : export PLUGIN_NAMESPACE ?= drone-gke
+docker-run-local : export PLUGIN_SECRET_TEMPLATE ?= $(CONFIG_HOME)/.kube.sec.yml
+docker-run-local : export PLUGIN_TEMPLATE ?= $(CONFIG_HOME)/.kube.yml
+docker-run-local : export PLUGIN_VARS_PATH ?= $(CONFIG_HOME)/vars.json
+docker-run-local : export PLUGIN_ZONE ?= zzz
+docker-run-local : export SECRET_API_TOKEN ?= 123
+docker-run-local : export SECRET_BASE64_P12_CERT ?= "cDEyCg=="
+docker-run-local : export docker_repo_name ?= $(docker_default_repo_name)
+docker-run-local : export docker_tag ?= $(docker_default_tag)
+docker-run-local : export docker_cmd ?= --dry-run --verbose
+
+# run docker container using local-example
+docker-run-local :
+	@[ -d $(CONFIG_HOME) ] || ( echo "$(CONFIG_HOME) does not exist" ; exit 1 )
+	@[ -f $(PLUGIN_SECRET_TEMPLATE) ] || ( echo "$(PLUGIN_SECRET_TEMPLATE) does not exist" ; exit 1 )
+	@[ -f $(PLUGIN_TEMPLATE) ] || ( echo "$(PLUGIN_TEMPLATE) does not exist" ; exit 1 )
+	@[ -f $(PLUGIN_VARS_PATH) ] || ( echo "$(PLUGIN_VARS_PATH) does not exist" ; exit 1 )
+	@[ -f $(GOOGLE_APPLICATION_CREDENTIALS) ] || ( echo "$(GOOGLE_APPLICATION_CREDENTIALS) does not exist" ; exit 1 )
+	@cd $(CONFIG_HOME) ; \
+	$(docker) run \
+		--env PLUGIN_CLUSTER=$(PLUGIN_CLUSTER) \
+		--env PLUGIN_NAMESPACE=$(PLUGIN_NAMESPACE) \
+		--env PLUGIN_SECRET_TEMPLATE=$(PLUGIN_SECRET_TEMPLATE) \
+		--env PLUGIN_TEMPLATE=$(PLUGIN_TEMPLATE) \
+		--env PLUGIN_VARS="$$(cat $(PLUGIN_VARS_PATH))" \
+		--env PLUGIN_ZONE=$(PLUGIN_ZONE) \
+		--env SECRET_API_TOKEN=$(SECRET_API_TOKEN) \
+		--env SECRET_BASE64_P12_CERT=$(SECRET_BASE64_P12_CERT) \
+		--env TOKEN="$$(cat $(GOOGLE_APPLICATION_CREDENTIALS))" \
+		--volume $(CONFIG_HOME):$(CONFIG_HOME) \
+		--workdir $(CONFIG_HOME) \
+		$(docker_repo_name)/$(docker_image_name):$(docker_tag) $(docker_cmd)
+
+.PHONY : docker-run-local
+
+.PHONY : dist