Perl

Overview

OKD provides S2I enabled Perl images for building and running Perl applications. The Perl S2I builder image assembles your application source with any required dependencies to create a new image containing your Perl application. This resulting image can be run either by OKD or by a container runtime.

Versions

Currently, OKD supports versions 5.16, 5.20, and 5.24 of Perl.

Images

Images comes in two flavors, depending on your needs:

• RHEL 7

• CentOS 7

RHEL 7 Based Images

The RHEL 7 images are available through the Red Hat Registry:

$ docker pull registry.redhat.io/openshift3/perl-516-rhel7
$ docker pull registry.redhat.io/rhscl/perl-520-rhel7
$ docker pull registry.redhat.io/rhscl/perl-524-rhel7

CentOS 7 Based Image

A CentOS image for Perl 5.16 is available on Docker Hub:

$ docker pull openshift/perl-516-centos7

To use these images, you can either access them directly from these image registries or push them into your OKD container image registry. Additionally, you can create an image stream that points to the image, either in your container image registry or at the external location. Your OKDt resources can then reference the ImageStream. You can find example image stream definitions for all the provided OKD images.

Build Process

S2I produces ready-to-run images by injecting source code into a container and letting the container prepare that source code for execution. It performs the following steps:

1. Starts a container from the builder image.

2. Downloads the application source.

3. Streams the scripts and application sources into the builder image container.

4. Runs the assemble script (from the builder image).

5. Saves the final image.

See S2I Build Process for a detailed overview of the build process.

Configuration

The Perl image supports a number of environment variables which can be set to control the configuration and behavior of the Perl runtime.

To set these environment variables as part of your image, you can place them into a .s2i/environment file inside your source code repository, or define them in the environment section of the build configuration’s **sourceStrategy** definition.

You can also set environment variables to be used with an existing image when creating new applications, or by updating environment variables for existing objects such as deployment configurations.

Accessing Logs

Access logs are streamed to standard output and as such they can be viewed using the oc logs command. Error logs are stored in the /tmp/error_log file, which can be viewed using the oc rsh command to access the container.

Hot Deploying

Hot deployment allows you to quickly make and deploy changes to your application without having to generate a new S2I build. To enable hot deployment in this image, you must set the **PERL_APACHE2_RELOAD** environment variable to true. For example, see the oc new-app command. You can use the oc set env command to update environment variables of existing objects.

To change your source code in a running pod, use the oc rsh command to enter the container:

$ oc rsh <pod_id>

After you enter into the running container, your current directory is set to /opt/app-root/src, where the source code is located.