Created Docker support with postgis instance (#2748)

Adapted README.md to indicate the new Docker support

Author: Stoiker

.dockerignore

@@ -0,0 +1,8 @@
+.dockerignore
+node_modules
+npm-debug.log
+Dockerfile
+.git
+.gitignore
+utils
+test

Dockerfile

@@ -0,0 +1,28 @@
+# Build Stage
+FROM node:8.15 AS BUILD
+
+WORKDIR /usr/src/app
+# Copy content of git repo to container
+COPY ./package.json /usr/src/app/
+COPY ./package-lock.json /usr/src/app/
+
+RUN npm install --only=production && npm prune --production
+
+# Production Stage
+FROM node:8.15-slim
+
+# Copy tilemill and node modules to new container
+WORKDIR /usr/src/app
+COPY --chown=node:node --from=BUILD /usr/src/app/node_modules /usr/src/app/node_modules
+COPY --chown=node:node . /usr/src/app
+
+RUN chmod 777 startdocker.sh
+
+USER node
+# Export port for tiles
+EXPOSE 20008
+# Export port for webpage
+EXPOSE 20009
+
+CMD ["node", "/usr/src/app/index.js", "--listenHost=0.0.0.0"]
+

README.md

@@ -43,7 +43,20 @@ Scripts have been created that will do most everything for you. They were writte
 
 [Full Installation instructions can be found in the TileMill Documentation](https://tilemill-project.github.io/tilemill/docs/install/).
 
+### Docker
+It is also possible to run tilemill as a docker container:
 
+    git clone https://github.com/tilemill-project/tilemill.git
+    cd tilemill
+    docker-compose up
+    
+This will host a docker container which uses the port 20008 and 20009 for tilemill, tilemill is then reachable under [http://localhost:20009](http://localhost:20009) .
+Additionally, a postgis instance is started as well which is reachable under 
+
+	host=localhost port=5432 user=docker password=docker dbname=gis
+
+Docker hosted volumes are used for the containers, hence if you want to use sqlite dbs you have to interact with those to get the dbs into the docker container.
+    
 # Build Status, Running Tests, Updating Documentation
 
 See CONTRIBUTING.md

docker-compose.yml

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+version: "3.3"
+services:
+  postgis:
+    image: kartoza/postgis:9.6-2.4
+    volumes:
+      - postgisVolume:/var/lib/postgresql
+    environment:
+      - POSTGRES_USER=docker
+      - POSTGRES_PASS=docker
+      - ALLOW_IP_RANGE=0.0.0.0/0
+    ports:
+      - "5432:5432"
+
+  tilemill:
+    build:
+      context: ./
+    ports:
+      - "20008:20008"
+      - "20009:20009"
+    volumes:
+      - tilemillVolume:/home/node/
+    environment:
+      - PGPORT=5432
+      - PGHOST=postgis
+      - PGDATABASE=gis
+      - PGUSER=docker
+      - PGPASSWORD=docker    
+    depends_on:
+      - postgis
+
+volumes:
+  postgisVolume:
+  tilemillVolume: