1. Introduction
  2. Run a PHP application in LAMP
  3. Linux Images - From debs to images
  4. Linux containers - From normal processes to containers
  5. Install Docker
  6. Running Containers
  7. Dockerfiles
  8. Volumes and Networks
  9. Docker Compose
  10. Final Assignment

Linux Containers

⏱ 9 mins remaining

Linux Images - From debs to images

What is inside a .deb ?

  1. Pick a .deb file from the APT cache /var/cache/apt/archives. Copy somewhere safe.
  2. Extract the .deb file ar and peak into its content using tar.
ar -x *.deb
tar -tf control.tar.zst
tar -tf data.tar.zst

  • Control Archive (control.tar.zst) This archive contains control files and scripts that manage the package installation, removal, and configuration. Key files include:

    • control: Contains metadata like package name, version, dependencies, and maintainer information.
    • postinst, preinst, postrm, prerm: Scripts executed during various stages of package installation and removal.

  • Data Archive (data.tar.zst): This archive contains the actual files to be installed on the system. It includes the directory structure and files that will be placed in their respective locations on the target system.

  • Debian Binary Control File (debian-binary): A text file indicating the Debian package format version. It typically contains the version number, such as “2.0” or “2.0\n”.

💡 What are the .deb limitations ?

Open Discussion: What do you think are .deb (native package management) limitations.

What is inside a container images ?

  1. Pick a container image from docker images output
  2. Save the image into a safe place using docker save -o output.tar
  3. extract the tar file and peak into its content
tar -xvf output.tar
tar -tf <layer1>.tar | less
tar -tf <layer2>.tar | less