Add alpine-based image

Dockerfile.alpine

@@ -0,0 +1 @@
+Dockerfile.alpine.3.9

Dockerfile.alpine.3.9

@@ -0,0 +1,8 @@
+FROM alpine:3.9
+RUN apk add --no-cache \
+    git \
+    python3
+COPY requirements.txt .
+RUN pip3 install --no-cache-dir -r requirements.txt
+RUN pre-commit sample-config > /.pre-commit-config.yaml
+ENTRYPOINT ["pre-commit", "run", "--config", "/.pre-commit-config.yaml"]

Makefile

@@ -4,6 +4,8 @@
 .DEFAULT_GOAL := help
 DOCKER=docker
 DOCKER_TAG=petzi/pre-commit
+DOCKER_TAG_ALPINE=$(DOCKER_TAG):alpine
+DOCKER_TAG_UBUNTU=$(DOCKER_TAG):ubuntu
 
 # The help command is inspired by this post:
 # https://marmelab.com/blog/2016/02/29/auto-documented-makefile.html
@@ -12,5 +14,7 @@ help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
 
 .PHONY: build
-build:  ## Build the image on development
+build:  ## Build the images on development
 	$(DOCKER) build -t $(DOCKER_TAG) .
+	$(DOCKER) build -f Dockerfile.alpine -t $(DOCKER_TAG_ALPINE) .
+	$(DOCKER) build -f Dockerfile.ubuntu -t $(DOCKER_TAG_UBUNTU) .