Update README.md

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README.md

@@ -1,23 +1,33 @@
 # simplexnoisemapgenerator
 
-This is an excersise in procedurally generating heightmaps. [Leaflet](http://leafletjs.com/) is used to display the results on a webpage.
+This is an exercise in procedurally generating heightmaps. [Leaflet] is used to display the results on a webpage.
 
 At this moment it is using two instances of simplex noise at different frequencies to generate heightmap. Biomes are calculated using elevation above sea level and rainfall value generated from another instance of simplex noise
 
 ## Installation
 
 Should be straightforward:
 
-1. Have `node.js` installed - 6.x is recommended but 5.x with `--harmony` flag should work as well
+1. Have `node.js` installed - 6.x or newer is required, 10.x is recommended (it's 2019!)
 1. Clone from github
-1. Install node-canvas dependencies - see [instructions here](https://github.com/Automattic/node-canvas) 
-  - Windows users: don't be afraid! It does work!
-  - Debian (and maybe Ubuntu) users: use `libjpeg62-turbo-dev` instead of `libjpeg8-dev`
+1. Install node-canvas dependencies - see [instructions here][node-canvas github]
+   - Windows users: don't be afraid! It does work!
+   - Debian (and maybe Ubuntu) users: use `libjpeg62-turbo-dev` instead of `libjpeg8-dev`
 1. Run `npm install`
 1. Run `node index.js`
 1. Go to [http://localhost:3000](http://localhost:3000)
 
-You might want to use [PM2](http://pm2.keymetrics.io/) to run several instances in parallel to quicker generate the tiles. Running `pm2 start index.js -i 0` will start a number of instances equal to the number of available CPU cores at your machine.
+You might want to use [PM2] to run several instances in parallel to quicker generate the tiles. Running `pm2 start index.js -i 0` will start a number of instances equal to the number of available CPU cores at your machine.
+
+### Docker
+
+There's an alpine based Dockerfile in repository with Node 10 and PM2 so just `docker build .` and `docker run -p3000:3000 %image%` and you should be good to go.
+
+For reasons unknown (I really don't fancy analyzing node-gyp's idiosyncrasies) building will occasionally fail on compiling native node packages. Just rerun until it succeeds.
+
+It fails 100% of time (sample size = 3) when using a Node 12 base image.
+
+By default PM2 is configured to run on as many cores, as available to docker. To change this setting either update `instances` in `ecosystem.config.js` to something else than `0`, or use [appropriate `docker run` configuration][Docker RUN cpuset-constraint docs]
 
 ## Static example
 ### 0.0.4 ![Example of generated map from 0.0.4](http://i.imgur.com/tzhL4Sr.png)
@@ -29,6 +39,7 @@ I have set it up on http://spigot.michaljarosz.net - the server is not very powe
 
 ## Version history
 
+* 0.0.5 - Package updates. Added Dockerfile. No functional changes.
 * 0.0.4 - Added biome generation based on Polygonal Map Generation for Game from Red Blob Games article (see below)
 * 0.0.3 - First released implementation. Heightmap only
 
@@ -40,3 +51,8 @@ I have set it up on http://spigot.michaljarosz.net - the server is not very powe
 ## License
 
 MIT
+
+[Docker RUN cpuset-constraint docs]: https://docs.docker.com/engine/reference/run/#cpuset-constraint
+[Leaflet]: http://leafletjs.com/
+[node-canvas github]: https://github.com/Automattic/node-canvas
+[PM2]: http://pm2.keymetrics.io/