chore(docker): add tools for generating docker images

Makefile

@@ -0,0 +1,98 @@
+# ==============================================================================
+# Welcome to the Makefile
+# ==============================================================================
+#
+# This Makefile contains a series of tasks which can help with building, testing
+# and working with the app. The following tasks are available to you:
+#
+# Image building & releasing actions:
+#
+#   make docker-build      - Builds a production Docker image.
+#   make docker-ci-build   - Builds an image without any asset compilation,
+#                            ideal for running test suites and similar tasks.
+#   make docker-image      - Builds a production Docker image and tags it as
+#                            appropriate based on the current branch & tag.
+#   make docker-release    - Builds a production Docker image and uploads to the
+#                            registry.
+#
+
+# ==============================================================================
+# Configuration
+# ==============================================================================
+
+# Docker image name to release the production image as.
+DOCKER_IMAGE := postalhq/postal
+
+# Path to bundle config
+BUNDLE_CONFIG ?= $(HOME)/.bundle/config
+
+# Detect if a tty is available
+TTY := $(shell [ -t 0 ] && echo 1)
+
+# Tag names
+DOCKER_TAG_NAME ?= $(shell git rev-parse --abbrev-ref HEAD 2>/dev/null)
+DOCKER_TAG_VERSION ?= $(shell git describe --tags --exact-match 2>/dev/null)
+
+ifeq ($(DOCKER_TAG_NAME),master)
+	DOCKER_TAG_NAME = latest
+endif
+
+ifeq ($(DOCKER_TAG_NAME),main)
+	DOCKER_TAG_NAME = latest
+endif
+
+# Version string to use
+VERSION ?= $(DOCKER_TAG_VERSION)
+ifeq ($(VERSION),)
+	VERSION = $(shell git describe --tags 2>/dev/null)
+endif
+
+ifeq ($(VERSION),)
+	VERSION = 0.0.0-dev
+endif
+
+# ==============================================================================
+# Image Building
+# ==============================================================================
+
+DOCKER_BUILD_CMD = DOCKER_BUILDKIT=1 docker \
+	build $(if $(TTY),,--progress plain) \
+	--build-arg VERSION=$(VERSION) \
+	--secret "id=bundle_config,src=$(BUNDLE_CONFIG)" \
+	.
+
+DOCKER_CI_BUILD_CMD = $(DOCKER_BUILD_CMD) --target=ci
+
+.PHONY: docker-build
+docker-build:
+	$(DOCKER_BUILD_CMD)
+
+.PHONY: docker-ci-build
+docker-ci-build:
+	$(DOCKER_CI_BUILD_CMD)
+
+# ==============================================================================
+# Image Tagging
+# ==============================================================================
+
+.PHONY: docker-image
+docker-image: docker-build
+	$(eval IMAGE := $(shell $(DOCKER_BUILD_CMD) -q))
+ifeq ($(DOCKER_TAG_NAME),latest)
+	docker tag "$(IMAGE)" "$(DOCKER_IMAGE):$(DOCKER_TAG_NAME)"
+endif
+
+# ==============================================================================
+# Image Releasing
+# ==============================================================================
+
+.PHONY: docker-release
+docker-release: docker-image
+ifeq ($(DOCKER_TAG_NAME),latest)
+	docker push "$(DOCKER_IMAGE):$(DOCKER_TAG_NAME)"
+endif
+ifneq ($(DOCKER_TAG_VERSION),)
+	docker tag "$(DOCKER_IMAGE):$(DOCKER_TAG_NAME)" \
+		"$(DOCKER_IMAGE):$(DOCKER_TAG_VERSION)" && \
+		docker push "$(DOCKER_IMAGE):$(DOCKER_TAG_VERSION)"
+endif