How to make ffmpeg available inside my Docker container? : <p>I'm currently trying to run a <code>ffmpeg</code> Docker image inside my own container with <code>docker-compose</code> using the <code>depends_on</code> clause. But when I try to reach <code>ffmpeg</code> inside my code, it seems like it's not available system-wide and I get an error. I believe I'm misconfiguring Docker.</p>

<p>My current <code>Dockerfile</code> is as follows:</p>

<pre><code>FROM node:9

WORKDIR /usr/app

COPY package*.json ./

RUN npm install --quiet

COPY . .
</code></pre>

<p>And my <code>docker-compose.yml</code>:</p>

<pre><code>version: '3'
services:
  app:
    build: .
    command: npm run dev
    volumes:
    - .:/usr/app/
    - /usr/app/node_modules
    ports:
      - "3000:3000"
    depends_on:
      - ffmpeg
  ffmpeg:
    image: jrottenberg/ffmpeg:3.3
</code></pre>

<p>When I run <code>docker-compose up</code> I can see that the <code>ffmpeg</code> is actually working, but then my application proceeds to start and it seems that <code>ffmpeg</code> ceases to work.</p>
