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PHP 7.4 container image

This container image includes PHP 7.4 as a S2I base image for your PHP 7.4 applications. Users can choose between RHEL and CentOS based builder images. The RHEL UBI images are available in the Red Hat Container Catalog, and the Fedora images are available in Fedora Registry. The resulting image can be run using podman.

Note: while the examples in this README are calling podman, you can replace any such calls by docker with the same arguments

Description

PHP 7.4 available as container is a base platform for building and running various PHP 7.4 applications and frameworks. PHP is an HTML-embedded scripting language. PHP attempts to make it easy for developers to write dynamically generated web pages. PHP also offers built-in database integration for several commercial and non-commercial database management systems, so writing a database-enabled webpage with PHP is fairly simple. The most common use of PHP coding is probably as a replacement for CGI scripts.

This container image includes an npm utility, so users can use it to install JavaScript modules for their web applications. There is no guarantee for any specific npm or nodejs version, that is included in the image; those versions can be changed anytime and the nodejs itself is included just to make the npm work.

Usage in OpenShift

In this example, we will assume that you are using the ubi8/php-74 image, available via php:74 imagestream tag in Openshift.

To build a simple cakephp-sample-app application in Openshift:

oc new-app php:7.4~https://github.com/sclorg/cakephp-ex.git

To access the application:

$ oc get pods
$ oc exec <pod> -- curl 127.0.0.1:8080

Accessing the application:

$ curl 127.0.0.1:8080

Source-to-Image framework and scripts

This image supports the Source-to-Image (S2I) strategy in OpenShift. The Source-to-Image is an OpenShift framework which makes it easy to write images that take application source code as an input, use a builder image like this PHP container image, and produce a new image that runs the assembled application as an output.

To support the Source-to-Image framework, important scripts are included in the builder image:

  • The /usr/libexec/s2i/assemble script inside the image is run to produce a new image with the application artifacts. The script takes sources of a given application and places them into appropriate directories inside the image. It utilizes some common patterns in PHP application development (see the Environment variables section below).
  • The /usr/libexec/s2i/run script is set as the default command in the resulting container image (the new image with the application artifacts). It runs httpd with PHP support enabled.

Building an application using a Dockerfile

Compared to the Source-to-Image strategy, using a Dockerfile is a more flexible way to build a PHP container image with an application. Use a Dockerfile when Source-to-Image is not sufficiently flexible for you or when you build the image outside of the OpenShift environment.

To use the PHP image in a Dockerfile, follow these steps:

1. Pull a base builder image to build on

podman pull ubi8/php-74

An UBI image ubi8/php-74 is used in this example. This image is usable and freely redistributable under the terms of the UBI End User License Agreement (EULA). See more about UBI at UBI FAQ.

2. Pull an application code

An example application available at https://github.com/sclorg/cakephp-ex.git is used here. Feel free to clone the repository for further experiments.

git clone https://github.com/sclorg/cakephp-ex.git app-src

3. Prepare an application inside a container

This step usually consists of at least these parts:

  • putting the application source into the container
  • installing the dependencies
  • setting the default command in the resulting image

For all these three parts, users can either setup all manually and use commands ./composer.phar or other commands explicitly in the Dockerfile (3.1.), or users can use the Source-to-Image scripts inside the image (3.2.; see more about these scripts in the section "Source-to-Image framework and scripts" above), that already know how to set-up and run some common PHP applications.

3.1. To use your own setup, create a Dockerfile with this content:
FROM ubi8/php-74

# Add application sources
ADD app-src .

# Install the dependencies
RUN TEMPFILE=$(mktemp) && \
    curl -o "$TEMPFILE" "https://getcomposer.org/installer" && \
    php <"$TEMPFILE" && \
    ./composer.phar install --no-interaction --no-ansi --optimize-autoloader

# Run script uses standard ways to configure the PHP application
# and execs httpd -D FOREGROUND at the end
# See more in <version>/s2i/bin/run in this repository.
# Shortly what the run script does: The httpd daemon and php needs to be
# configured, so this script prepares the configuration based on the container
# parameters (e.g. available memory) and puts the configuration files into
# the approriate places.
# This can obviously be done differently, and in that case, the final CMD
# should be set to "CMD httpd -D FOREGROUND" instead.
CMD /usr/libexec/s2i/run
3.2. To use the Source-to-Image scripts and build an image using a Dockerfile, create a Dockerfile with this content:
FROM ubi8/php-74

# Add application sources to a directory that the assemble script expects them
# and set permissions so that the container runs without root access
USER 0
ADD app-src /tmp/src
RUN chown -R 1001:0 /tmp/src
USER 1001

# Install the dependencies
RUN /usr/libexec/s2i/assemble

# Set the default command for the resulting image
CMD /usr/libexec/s2i/run

4. Build a new image from a Dockerfile prepared in the previous step

podman build -t cakephp-app .

5. Run the resulting image with the final application

podman run -d cakephp-app

Environment variables for Source-to-Image

To set these environment variables, you can place them as a key value pair into a .s2i/environment file inside your source code repository.

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

  • ERROR_REPORTING
    • Informs PHP of which errors, warnings and notices you would like it to take action for
    • Default: E_ALL & ~E_NOTICE
  • DISPLAY_ERRORS
    • Controls whether or not and where PHP will output errors, notices and warnings
    • Default: ON
  • DISPLAY_STARTUP_ERRORS
    • Cause display errors which occur during PHP's startup sequence to be handled separately from display errors
    • Default: OFF
  • TRACK_ERRORS
    • Store the last error/warning message in $php_errormsg (boolean)
    • Default: OFF
  • HTML_ERRORS
    • Link errors to documentation related to the error
    • Default: ON
  • INCLUDE_PATH
    • Path for PHP source files
    • Default: .:/opt/app-root/src:/opt/rh/rh-php74/root/usr/share/pear (EL7)
    • Default: .:/opt/app-root/src:/usr/share/pear (EL8, Fedora)
  • PHP_MEMORY_LIMIT
    • Memory Limit
    • Default: 128M
  • SESSION_NAME
    • Name of the session
    • Default: PHPSESSID
  • SESSION_HANDLER
    • Method for saving sessions
    • Default: files
  • SESSION_PATH
    • Location for session data files
    • Default: /tmp/sessions
  • SESSION_COOKIE_DOMAIN
    • The domain for which the cookie is valid.
    • Default:
  • SESSION_COOKIE_HTTPONLY
    • Whether or not to add the httpOnly flag to the cookie
    • Default: 0
  • SESSION_COOKIE_SECURE
    • Specifies whether cookies should only be sent over secure connections.
    • Default: Off
  • SHORT_OPEN_TAG
    • Determines whether or not PHP will recognize code between tags
    • Default: OFF
  • DOCUMENTROOT
    • Path that defines the DocumentRoot for your application (ie. /public)
    • Default: /

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

  • OPCACHE_MEMORY_CONSUMPTION
    • The OPcache shared memory storage size in megabytes
    • Default: 128
  • OPCACHE_REVALIDATE_FREQ
    • How often to check script timestamps for updates, in seconds. 0 will result in OPcache checking for updates on every request.
    • Default: 2
  • OPCACHE_MAX_FILES
    • The maximum number of keys (scripts) in the OPcache hash table. Only numbers between 200 and 1000000 are allowed.
    • Default: 4000

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

  • PHPRC
    • Sets the path to the php.ini file
  • PHP_INI_SCAN_DIR
    • Path to scan for additional ini configuration files

You can override the Apache MPM prefork settings to increase the performance for of the PHP application. In case you set some Cgroup limits, the image will attempt to automatically set the optimal values. You can override this at any time by specifying the values yourself:

  • HTTPD_START_SERVERS

    • The StartServers directive sets the number of child server processes created on startup.
    • Default: 8

  • HTTPD_MAX_REQUEST_WORKERS

    • The MaxRequestWorkers directive sets the limit on the number of simultaneous requests that will be served.
    • MaxRequestWorkers was called MaxClients before version httpd 2.3.13.
    • Default: 256 (this is automatically tuned by setting Cgroup limits for the container using this formula: TOTAL_MEMORY / 15MB. The 15MB is average size of a single httpd process.

  • HTTPD_MAX_REQUESTS_PER_CHILD

    • The MaxRequestsPerChild directive sets the limit on the number of connections that an individual child server process will handle. After MaxRequestsPerChild connections, the child process will die. If MaxRequestsPerChild is 0, then the process will never expire.
    • Setting MaxRequestsPerChild to a non-zero value limits the amount of memory that a process can consume by (accidental) memory leakage.
    • MaxRequestsPerChild is called MaxConnectionsPerChild in Apache HTTP 2.3.9 and later.
    • Default: 4000

  • HTTPD_MAX_KEEPALIVE_REQUESTS

    • The MaxKeepAliveRequests directive limits the number of requests allowed per connection when KeepAlive is on. If it is set to 0, unlimited requests will be allowed.
    • Default: 100

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

    • COMPOSER_MIRROR
      • Adds a custom composer repository mirror URL to composer configuration. Note: This only affects packages listed in composer.json.
    • COMPOSER_INSTALLER
    • COMPOSER_VERSION
      • Overrides the default composer version to install (1, 2, preview, snapshot or version="x.y.z")
    • COMPOSER_ARGS
      • Adds extra arguments to the composer install command line (for example --no-dev).

Source repository layout

You do not need to change anything in your existing PHP project's repository. However, if these files exist they will affect the behavior of the build process:

  • composer.json

    List of dependencies to be installed with composer. The format is documented here.

  • .htaccess

    In case the DocumentRoot of the application is nested within the source directory /opt/app-root/src, users can provide their own Apache .htaccess file. This allows the overriding of Apache's behavior and specifies how application requests should be handled. The .htaccess file needs to be located at the root of the application source.

Hot deploy

In order to immediately pick up changes made in your application source code, you need to run your built image with the OPCACHE_REVALIDATE_FREQ=0 environment variable passed to Podman -e run flag:

$ podman run -e OPCACHE_REVALIDATE_FREQ=0 -p 8080:8080 php-app

To change your source code in running container, use Podman's exec) command:

podman exec -it <CONTAINER_ID> /bin/bash

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

Extending image

Not only content, but also startup scripts and configuration of the image can be extended using source-to-image.

The structure of the application can look like this:

Folder name Description
./httpd-cfg Can contain additional Apache configuration files (*.conf)
./httpd-ssl Can contain own SSL certificate (in certs/ subdirectory) and key (in private/ subdirectory)
./php-pre-start Can contain shell scripts (*.sh) that are sourced before httpd is started
./php-post-assemble Can contain shell scripts (*.sh) that are sourced at the end of assemble script
./ Application source code

See also

Dockerfile and other sources are available on https://github.com/sclorg/s2i-php-container. In that repository you also can find another versions of Python environment Dockerfiles. Dockerfile for RHEL8 is called Dockerfile.rhel8 and the Fedora Dockerfile is called Dockerfile.fedora.

Security Implications

-p 8080:8080

 Opens  container  port  8080  and  maps it to the same port on the Host.