chore: migrate to Go modules

Makefile

@@ -3,25 +3,24 @@ SHELL := /bin/zsh
 PLATFORM=linux
 # ARCH := $(shell go env GOARCH)
 ARCH := amd64
-GOPATH := $(shell go env GOPATH)
-GOBIN := $(GOPATH)/bin
 TARGET := websocket-proxy
-# Go related variables.
-GO_PATH := $(PWD):$(PWD)/vendor:$(GOPATH)
 VERSION := 0.0.1
 ifeq (run,$(firstword $(MAKECMDGOALS)))
   # use the rest as arguments for "run"
   RUN_ARGS := $(wordlist 2,$(words $(MAKECMDGOALS)),$(MAKECMDGOALS))
-  # ...and turn them into do-nothing targets
-#   $(eval $(RUN_ARGS):;@:)
+  # Allow the remaining goals to be passed through as bootstrap servers.
+  %:
+	@:
 endif
 
+.PHONY: all build docker run vendor update-deps
+
 all: build docker
 
 build:
-	@echo ".:: buiding binary for $(PLATFORM) ::."
+	@echo ".:: building binary for $(PLATFORM) ::."
 	@rm -f $(TARGET)
-	@GOPATH=$(GO_PATH) GOOS=$(PLATFORM) GOARCH=$(ARCH) go build -o $(TARGET) .
+	@GOOS=$(PLATFORM) GOARCH=$(ARCH) go build -o $(TARGET) .
 
 docker:
 	@echo ".:: building docker image ::."
@@ -33,7 +32,11 @@ run:
 	@go run serv.go -addr :9000 --bootstrap-servers $(RUN_ARGS)
 
 vendor:
-	@echo ".:: update submodule ::."
-	@git submodule init
-	@git submodule update
-	@dep update
+	@echo ".:: synchronizing vendored Go modules ::."
+	@go mod vendor
+
+update-deps:
+	@echo ".:: updating Go dependencies ::."
+	@go get -u ./...
+	@go mod tidy
+	@go mod vendor