build(docker): move Markdownlint

Move Markdownlint into the main Dockerfile and a service to the Docker
Compose override file.

Dockerfile

@@ -1,3 +1,15 @@
+FROM node:14-alpine AS markdownlint
+
+RUN npm install -g markdownlint-cli
+
+USER node
+
+ENTRYPOINT ["markdownlint"]
+
+CMD ["/data"]
+
+###
+
 FROM node:14-alpine AS assets
 
 ARG NODE_ENV="production"

docker-compose.override.yaml.example

@@ -23,3 +23,10 @@ services:
   js:
     <<: *default-assets
     command: "./run yarn:build:js"
+
+  markdownlint:
+    build:
+      context: "."
+      target: "markdownlint"
+    volumes:
+      - "./source:/data/source"

markdownlint.Dockerfile

@@ -1,5 +0,0 @@
-FROM node:14-alpine
-ENTRYPOINT ["markdownlint"]
-CMD ["/data"]
-WORKDIR /root
-RUN npm install -g markdownlint-cli

run

@@ -46,17 +46,8 @@ function help {
   printf "\nExtended help:\n  Each task has comments for general usage\n"
 }
 
-function markdownlint:build {
-  docker image build . \
-    -f markdownlint.Dockerfile \
-    -t markdownlint
-}
-
-function markdownlint:run {
-  docker container run --rm \
-    -v $(pwd)/.markdownlint.yaml:/root/.markdownlint.yaml \
-    -v $(pwd)/source:/data \
-    markdownlint
+function lint:markdown {
+  docker-compose run --rm markdownlint "${@}"
 }
 
 function run-production {