This is an image based on the official PHP image with some additions.
Several commonly used extensions are added. The list includes but is not limited to mysql, pgsql, memcached, yaml, pdo, opcache, xhprof, and others. See the Dockerfile or composer.json for a complete list of extensions.
A non-system user is created to run PHP and is the default user for the image. The username defaults to php and can be set with the build argument STDUSER.
The timezone is explicitly set and defaults to UTC. It can be changed at build time by setting the build argument TIMEZONE.
Dockerize is installed to allow for using environment variables in config files.
The latest version of composer is installed at the time of building.
SSTMP is installed to allow for sending mail inside the container. The config file uses environment variables.
SMTP_ROOT_ADDRESS
The user that gets all the mails (UID < 1000, usually the admin)
SMTP_HOST
The mail server (where the mail is sent to), both port 465 or 587 should be acceptable. See also http://mail.google.com/support/bin/answer.py?answer=78799
REWRITE_DOMAIN
The address where the mail appears to come from for user authentication.
FQDN
The full hostname
USE_TLS
Use SSL/TLS
USE_START_TLS
Use SSL/TLS before starting negotiation
FROM_LINE_OVERRIDE
Email 'From header's can override the default domain?
AUTH_USER, AUTH_PASS, AUTH_METHOD
SMTP Auth settings