Three Docker concepts

Differencies between Dockerfile, Docker Image and Docker Container
21 August 2017   1453

Dockerfile is a file that you create which in turn produces a Docker image when you build it.

A Docker image is created by two actions:

  1. The first action is to create a Dockerfile
  2. The second action is to run some type of build command that uses the Dockerfile

Dockerfile is a text file that Docker reads in from top to bottom. It contains a bunch of instructions which informs Docker HOW the Docker image should get built.

In other worlds, a Dockerfile is a recipe (or blueprint if that helps) for building Docker images, and the act of running a separate build command produces the Docker image from that recipe.

When you run a Docker image, it creates a Docker container.

Let's sum up:

  • Dockerfile is a "recipe" for Docker
  • A Docker image is created by running a Docker command (which uses that Dockerfile)
  • A Docker container is a running instance of a Docker image

Learn more here.

Canonical to Represent Minimal Ubuntu

New version of Ubuntu is created for servers, isolated containers based on Docker and cloud systems
12 July 2018   661

Ubuntu team presented a simplified version of the base image - Minimal Ubuntu. It is designed for servers, isolated containers based on Docker and cloud systems. The release features high performance, minimal load time and automation of applications in the cloud.

The small footprint of Minimal Ubuntu, when deployed with fast VM provisioning from GCE, helps deliver drastically improved boot times, making them a great choice for developers looking to build their applications on Google Cloud Platform.

Paul Nash

Group Product Manager, Google Cloud

The authors of the project emphasize the size of the distribution kit, which "weighs" 157 MB, and also supports the main cloud systems like Amazon EC2, Google Compute Engine (GCE), LXD and KVM / OpenStack, each of which has its own optimized version of the package. In addition, the OS-based image for operating with containers based on the Docker platform, compatible with the Kubernetes.

Minimal Ubuntu is designed for automated execution, so it includes only a minimal set of tools. The distribution can be upgraded to a set of Ubuntu Server packages using the special utility "unminimize", which returns components that are convenient for interactive management.

According to Canonical representatives, the deletion of the manual control functions resulted in the acceleration of the load time by 40% and the reduction of the occupied disk space by 50%. At the same time, this release remained completely compatible with all the packages from standard Ubuntu repositories. Required packages can be installed using the standard package manager apt or using snapd, which are included in the distribution by default.

Two assemblies are available for download, based on Ubuntu 16.04 LTS and 18.04 LTS. You can download them on the official website.