Ubuntu – Ubuntu for Docker Containers

14.04docker

Is Ubuntu a suitable distro for using inside a Docker container? If so, how does the Ubuntu installed by

docker pull ubuntu

differ from Ubuntu 14.04?

Best Answer

The Official Ubuntu base image available at Docker Hub Registry is based on Ubuntu Core released by Canonical.

Core's page on Ubuntu Wiki explicitly states it is suitable for use in Docker (emphasis mine):

Ubuntu Core is a minimal rootfs for use in the creation of custom images for specific needs. Ubuntu Core strives to create a suitable minimal environment for use in Board Support Packages, constrained or integrated environments, as the basis for application demonstration images, or Linux containers such as LXC or Docker.

The manifest file contains the list of pre-installed packages. Of course, you can install any package available in the Ubuntu repos, but you may have a hard time trying to run GUI applications inside a container.

Related Solutions

Ubuntu – Unable to locate package libc6-dbg:i386 in docker

I'll answer this myself.

The information needed for figuring this out is at https://wiki.debian.org/Multiarch/HOWTO.

Apt in the official docker ubuntu image and also in phusion/baseimage is configured only with support for the amd64. This is what it tells you if you ask:

# dpkg --print-architecture
amd64
# dpkg --print-foreign-architectures
<no output>

The way to fix this is to add another architecture before the apt-get update:

# dpkg --add-architecture i386
# apt-get update
<lots of lines>
# apt-get install libc6-dbg:i386
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  gcc-4.9-base:i386 libc6:i386 libgcc1:i386
Suggested packages:
  glibc-doc:i386 locales:i386
The following NEW packages will be installed:
  gcc-4.9-base:i386 libc6:i386 libc6-dbg:i386 libgcc1:i386
0 upgraded, 4 newly installed, 0 to remove and 21 not upgraded.
Need to get 7039 kB of archives.
After this operation, 26.4 MB of additional disk space will be used.
Do you want to continue? [Y/n]

For completeness, here is the final Dockerfile:

FROM ubuntu:14.04

MAINTAINER Me <xyz@example.com>

RUN dpkg --add-architecture i386
RUN apt-get update
RUN apt-get install libc6-dbg
RUN apt-get install libc6-dbg:i386

Ubuntu – How to configure locales to Unicode in a Docker Ubuntu 14.04 container

The /etc/default/locale file is loaded by PAM; see /etc/pam.d/login for example. However, PAM is not invoked when running a command in a Docker container. To configure the locale, simply set the relevant environment variable in your Dockerfile. Example:

FROM ubuntu:trusty
ENV LANG en_US.UTF-8
CMD ["/bin/bash"]

Best Answer

Related Solutions

Ubuntu – Unable to locate package libc6-dbg:i386 in docker

Ubuntu – How to configure locales to Unicode in a Docker Ubuntu 14.04 container

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