title: I cannot install yum in my docker container
body: <p>I have a <code>docker container</code> which was built by a <code>keycloak</code> image.</p>
  
  <p>I want to install <code>vim</code> in the container but I found that I need to have <code>yum</code> in order to install the <code>vim</code>. I tried to download <code>yum</code> from the internet and use rpm to install it, but the container didn't have <code>sudo</code> to let me change the file permission.</p>
  
  <p>Following is my linux version:</p>
  
  <pre><code>NAME="Red Hat Enterprise Linux"
  VERSION="8.0 (Ootpa)"
  ID="rhel"
  ID_LIKE="fedora"
  VERSION_ID="8.0"
  PLATFORM_ID="platform:el8"
  PRETTY_NAME="Red Hat Enterprise Linux 8.0 (Ootpa)"
  ANSI_COLOR="0;31"
  CPE_NAME="cpe:/o:redhat:enterprise_linux:8.0:GA"
  HOME_URL="https://www.redhat.com/"
  BUG_REPORT_URL="https://bugzilla.redhat.com/"
  
  REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 8"
  REDHAT_BUGZILLA_PRODUCT_VERSION=8.0
  REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
  REDHAT_SUPPORT_PRODUCT_VERSION="8.0" 
  </code></pre>
  
  <p>How can I get any text editor installed in the container?</p>