title: Can't use curl inside a docker container that has installed it before
body: <p>I'm using RestHeart docker image.</p>
  
  <p>From it's <a href="https://hub.docker.com/r/softinstigate/restheart/dockerfile/" rel="nofollow noreferrer">dockerfile</a>:</p>
  
  <pre><code>FROM openjdk:8u111-jre-alpine
  
  RUN apk upgrade --update &amp;&amp; apk add --update libstdc++ curl ca-certificates bash
  
  ...
  </code></pre>
  
  <p>This means that curl is currently installed, right?</p>
  
  <p>I run that image inside a Docker compose:</p>
  
  <pre><code>version: '3.4'
  services:
  
    mongodb:
      image: mongo:4.0
      ports:
        - 27017:27017
  
    restheart:
      image: softinstigate/restheart:3.10.0
      ports:
        - 8082:8080
      volumes:
        - ./restheart:/opt/restheart/etc:ro
      depends_on:
        - mongodb
  </code></pre>
  
  <p>The container id for restheart container is <code>e1a023d9a8a9</code>.</p>
  
  <p>But when I execute <code>docker exec e1a023d9a8a9 curl</code> I get:</p>
  
  <blockquote>
    <p>OCI runtime exec failed: exec failed: container_linux.go:346: starting
    container process caused "exec: \"curl\": executable file not found in
    $PATH": unknown</p>
  </blockquote>