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Last pushed: 6 days ago
Short Description
Base image which allows using of source-to-image.
Full Description

OpenShift base images

This repository contains Dockerfiles for images which can be used as base images
to add support for source-to-image.

Installation and Usage

Choose either the CentOS7 or RHEL7 base image:

  • RHEL7 base image

To build a RHEL7 based image, you need to build it on properly subscribed RHEL machine.

$ git clone --recursive
$ cd s2i-base-container
$ make build VERSIONS=core TARGET=rhel7
  • CentOS7 base image

This image is available on DockerHub. To download it run:

docker pull sclorg/s2i-core-centos7

To build a Base image from scratch run:

$ git clone --recursive
$ cd s2i-base-container
$ make build VERSIONS=core

Notice: By omitting the VERSION parameter, the build/test action will be performed
on all provided versions of s2i image.

Software Collections in S2I images

OpenShift S2I images use Software Collections
packages to provide the latest versions of various software.
The SCL packages are released more frequently than the RHEL or CentOS systems,
which are unlikely to change for several years.
We rely on RHEL and CentOS for base images, on the other hand,
because those are stable, supported, and secure platforms.

Normally, SCL requires manual operation to enable the collection you want to use.
This is burdensome and can be prone to error.
The OpenShift S2I approach is to set Bash environment variables that
serve to automatically enable the desired collection:

  • BASH_ENV: enables the collection for all non-interactive Bash sessions
  • ENV: enables the collection for all invocations of /bin/sh
  • PROMPT_COMMAND: enables the collection in interactive shell

Two examples:

  • If you specify BASH_ENV, then all your #!/bin/bash scripts
    do not need to call scl enable.
  • If you specify PROMPT_COMMAND, then on execution of the
    docker exec ... /bin/bash command, the collection will be automatically enabled.

Executables in Software Collections packages (e.g., ruby)
are not directly in a directory named in the PATH environment variable.
This means that you cannot do:

$ docker exec <cid> ... ruby

but must instead do:

$ docker exec <cid> ... /bin/bash -c ruby

The /bin/bash -c, along with the setting the appropriate environment variable,
ensures the correct ruby executable is found and invoked.

Docker Pull Command

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