ffmpeg install within existing Node.js docker image

Question

I need to use ffmpeg in a Node.js application that runs in a docker container (created using docker-compose). I'm very new to Docker, and would like to know how to command Docker to install ffmpeg when creating the image.

DockerFile

FROM node:carbon
WORKDIR /usr/src/app

# where available (npm@5+)
COPY package*.json ./
RUN npm install -g nodemon
RUN npm install --only=production
COPY . .

EXPOSE 3000
CMD [ "npm", "start" ] 

package.json:

{
  "name": "radcast-apis",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node ./bin/www",
    "dev": "nodemon --inspect-brk=0.0.0.0:5858 ./bin/www"
  },
  "dependencies": {
    "audioconcat": "^0.1.3",
    "cookie-parser": "~1.4.3",
    "debug": "~2.6.9",
    "express": "~4.16.0",
    "firebase-admin": "^5.12.1",
    "http-errors": "~1.6.2",
    "jade": "~1.11.0",
    "morgan": "~1.9.0"
  },
  "devDependencies": {
    "nodemon": "^1.11.0"
  }
}

docker-compose.yml:

version: "2"
services:
  web:
    volumes:
    - "./app:/src/app"
    build: .
    command: npm run dev
    ports:
    - "3000:3000"
    - "5858:5858"

Answer 1

If it helps anyone, I figured out a way.

• Use ffmpeg-static by adding the entry to package.json "ffmpeg-static": "^2.3.0", this makes the binary files available in the docker container.
• By using ffmpeg_static = require('ffmpeg-static') and then inspecting the path property on ffmpeg_static, you can see where the binaries are in the container.
• Add this path to an ENV variable: ENV PATH="/your/path/to/node_modules/ffmpeg-static/bin/linux/x64:${PATH}"

That worked a trick for us! The answer that saved us was an analogous use-case for firebase cloud functions - here.