I am using this dockerfile for Meteor + Graphicsmagick and using MUP to deploy it.

Make this change to your mup.js file

docker: {
  image: "joshjoe/meteor-graphicsmagick",
},

Then make sure you are also making a volume available to docker if you want to map something to a permenant location so your files arenn't deleted when you do new mup deploys.

volumes: {
  "/opt/uploads": "/uploads"
},

Here is my who mup.js file for reference.

module.exports = { servers: { one: { host: '1.2.3.4', username: 'myusername', pem:'/Users/mylocalusername/.ssh/do', opts: { port: 1235 } } }, meteor: { name: 'meteorapp', path: '/Users/mylocalusername/meteor/meteorapp', volumes: { "/opt/uploaddirectory": "/uploaddirectory" }, docker: { image: "joshjoe/meteor-graphicsmagick", }, servers: { one: {} }, buildOptions: { debug: true, serverOnly: true, }, env: { PORT: "80", ROOT_URL: 'http://subdomain.domain.com', MONGO_URL: 'mongodb://localhost/meteor' }, deployCheckWaitTime: 120 }, mongo: { oplog: true, port: 27017, servers: { one: {}, }, }, };