PHP - Source-to-Image (S2I) | Using Images

Important

Azure Red Hat OpenShift 3.11 will be retired 30 June 2022. Support for creation of new Azure Red Hat OpenShift 3.11 clusters continues through 30 November 2020. Following retirement, remaining Azure Red Hat OpenShift 3.11 clusters will be shut down to prevent security vulnerabilities.

Follow this guide to create an Azure Red Hat OpenShift 4 cluster. If you have specific questions, please contact us

Overview
Versions
Images
Build Process
Configuration
- Apache Configuration
Accessing Logs
Hot Deploying

Overview

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

Versions

Currently, Azure Red Hat OpenShift provides versions 5.5, 5.6, and 7.0 of PHP.

Images

These images come 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/php-55-rhel7
$ docker pull registry.redhat.io/rhscl/php-56-rhel7
$ docker pull registry.redhat.io/rhscl/php-70-rhel7

CentOS 7 Based Images

CentOS images for PHP 5.5 and 5.6 are available on Docker Hub:

$ docker pull openshift/php-55-centos7
$ docker pull openshift/php-56-centos7

To use these images, you can either access them directly from these image registries or push them into your Azure Red Hat OpenShift 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 Azure Red Hat OpenShift resources can then reference the image stream.

You can find example image stream definitions for all the provided Azure Red Hat OpenShift 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:

Starts a container from the builder image.
Downloads the application source.
Streams the scripts and application sources into the builder image container.
Runs the assemble script (from the builder image).
Saves the final image.

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

Configuration

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

Environment variables that control build behavior must be set as part of the s2i build configuration or in the .s2i/environment file to make them available to the build steps.

The following environment variables set their equivalent property value in the php.ini file:

Table 1. PHP Environment Variables
Variable Name	Description	Default
`ERROR_REPORTING`	Informs PHP of the errors, warnings, and notices for which you would like it to take action.	E_ALL & ~E_NOTICE
`DISPLAY_ERRORS`	Controls if and where PHP outputs errors, notices, and warnings.	ON
`DISPLAY_STARTUP_ERRORS`	Causes any display errors that occur during PHP’s startup sequence to be handled separately from display errors.	OFF
`TRACK_ERRORS`	Stores the last error/warning message in `$php_errormsg` (boolean).	OFF
`HTML_ERRORS`	Links errors to documentation that is related to the error.	ON
`INCLUDE_PATH`	Path for PHP source files.	*.:/opt/openshift/src:/opt/rh/php55/root/usr/share/pear*
`SESSION_PATH`	Location for session data files.	*/tmp/sessions*
`DOCUMENTROOT`	Path that defines the document root for your application (for example, */public*).	/

The following environment variable sets its equivalent property value in the opcache.ini file:

Table 2. Additional PHP settings
Variable Name	Description	Default
`OPCACHE_MEMORY_CONSUMPTION`	The OPcache shared memory storage size.	16M
`OPCACHE_REVALIDATE_FREQ`	How often to check script time stamps for updates, in seconds. 0 results in OPcache checking for updates on every request.	2

You can also override the entire directory used to load the PHP configuration by setting:

Table 3. Additional PHP settings
Variable Name	Description
`PHPRC`	Sets the path to the *php.ini* file.
`PHP_INI_SCAN_DIR`	Path to scan for additional *.ini* configuration files

You can use a custom composer repository mirror URL to download packages instead of the default 'packagist.org':

Table 4. Composer Environment Variables
Variable Name	Description
`COMPOSER_MIRROR`	Set this variable to use a custom Composer repository mirror URL to download required packages during the build process. Note: This only affects packages listed in *composer.json*.

Apache Configuration

If the DocumentRoot of the application is nested in the source directory /opt/openshift/src, you can provide your own .htaccess file to override the default Apache behavior and specify how application requests should be handled. The .htaccess file must be located at the root of the application source.

Accessing Logs

Access logs are streamed to standard out 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. In order to immediately pick up changes made in your application source code, you must run your built image with the OPCACHE_REVALIDATE_FREQ=0 environment variable.

For example, see the oc new-app command. You can use the oc env command to update environment variables of existing objects.

You should only use this option while developing or debugging; it is not recommended to turn this on in your production environment.

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.