content.md 6.9 KB

What is WordPress?

WordPress is a free and open source blogging tool and a content management system (CMS) based on PHP and MySQL, which runs on a web hosting service. Features include a plugin architecture and a template system. WordPress is used by more than 22.0% of the top 10 million websites as of August 2013. WordPress is the most popular blogging system in use on the Web, at more than 60 million websites. The most popular languages used are English, Spanish and Bahasa Indonesia.

wikipedia.org/wiki/WordPress

%%LOGO%%

How to use this image

$ docker run --name some-%%REPO%% --link some-mysql:mysql -d %%IMAGE%%

The following environment variables are also honored for configuring your WordPress instance:

  • -e WORDPRESS_DB_HOST=... (defaults to the IP and port of the linked mysql container)
  • -e WORDPRESS_DB_USER=... (defaults to "root")
  • -e WORDPRESS_DB_PASSWORD=... (defaults to the value of the MYSQL_ROOT_PASSWORD environment variable from the linked mysql container)
  • -e WORDPRESS_DB_NAME=... (defaults to "wordpress")
  • -e WORDPRESS_TABLE_PREFIX=... (defaults to "", only set this when you need to override the default table prefix in wp-config.php)
  • -e WORDPRESS_AUTH_KEY=..., -e WORDPRESS_SECURE_AUTH_KEY=..., -e WORDPRESS_LOGGED_IN_KEY=..., -e WORDPRESS_NONCE_KEY=..., -e WORDPRESS_AUTH_SALT=..., -e WORDPRESS_SECURE_AUTH_SALT=..., -e WORDPRESS_LOGGED_IN_SALT=..., -e WORDPRESS_NONCE_SALT=... (default to unique random SHA1s)
  • -e WORDPRESS_DEBUG=1 (defaults to disabled, non-empty value will enable WP_DEBUG in wp-config.php)
  • -e WORDPRESS_CONFIG_EXTRA=... (defaults to nothing, non-empty value will be embedded verbatim inside wp-config.php -- especially useful for applying extra configuration values this image does not provide by default such as WP_ALLOW_MULTISITE; see docker-library/wordpress#142 for more details)

If the WORDPRESS_DB_NAME specified does not already exist on the given MySQL server, it will be created automatically upon startup of the %%REPO%% container, provided that the WORDPRESS_DB_USER specified has the necessary permissions to create it.

If you'd like to be able to access the instance from the host without the container's IP, standard port mappings can be used:

$ docker run --name some-%%REPO%% --link some-mysql:mysql -p 8080:80 -d %%IMAGE%%

Then, access it via http://localhost:8080 or http://host-ip:8080 in a browser.

If you'd like to use an external database instead of a linked mysql container, specify the hostname and port with WORDPRESS_DB_HOST along with the password in WORDPRESS_DB_PASSWORD and the username in WORDPRESS_DB_USER (if it is something other than root):

$ docker run --name some-%%REPO%% -e WORDPRESS_DB_HOST=10.1.2.3:3306 \
    -e WORDPRESS_DB_USER=... -e WORDPRESS_DB_PASSWORD=... -d %%IMAGE%%

When running WordPress with TLS behind a reverse proxy such as NGINX which is responsible for doing TLS termination, be sure to set X-Forwarded-Proto appropriately (see "Using a Reverse Proxy" in "Administration Over SSL" in upstream's documentation). No additional environment variables or configuration should be necessary (this image automatically adds the noted HTTP_X_FORWARDED_PROTO code to wp-config.php if any of the above-noted environment variables are specified).

If your database requires SSL, WordPress ticket #28625 has the relevant details regarding support for that with WordPress upstream. As a workaround, the "Secure DB Connection" plugin can be extracted into the WordPress directory and the appropriate values described in the configuration of that plugin added in wp-config.php.

Docker Secrets

As an alternative to passing sensitive information via environment variables, _FILE may be appended to the previously listed environment variables, causing the initialization script to load the values for those variables from files present in the container. In particular, this can be used to load passwords from Docker secrets stored in /run/secrets/<secret_name> files. For example:

$ docker run --name some-wordpress -e WORDPRESS_DB_PASSWORD_FILE=/run/secrets/mysql-root ... -d %%IMAGE%%:tag

Currently, this is supported for WORDPRESS_DB_HOST, WORDPRESS_DB_USER, WORDPRESS_DB_PASSWORD, WORDPRESS_DB_NAME, WORDPRESS_AUTH_KEY, WORDPRESS_SECURE_AUTH_KEY, WORDPRESS_LOGGED_IN_KEY, WORDPRESS_NONCE_KEY, WORDPRESS_AUTH_SALT, WORDPRESS_SECURE_AUTH_SALT, WORDPRESS_LOGGED_IN_SALT, WORDPRESS_NONCE_SALT, WORDPRESS_TABLE_PREFIX, and WORDPRESS_DEBUG.

%%STACK%%

Run docker stack deploy -c stack.yml %%REPO%% (or docker-compose -f stack.yml up), wait for it to initialize completely, and visit http://swarm-ip:8080, http://localhost:8080, or http://host-ip:8080 (as appropriate).

Adding additional libraries / extensions

This image does not provide any additional PHP extensions or other libraries, even if they are required by popular plugins. There are an infinite number of possible plugins, and they potentially require any extension PHP supports. Including every PHP extension that exists would dramatically increase the image size.

If you need additional PHP extensions, you'll need to create your own image FROM this one. The documentation of the php image explains how to compile additional extensions. Additionally, the wordpress Dockerfile has an example of doing this.

The following Docker Hub features can help with the task of keeping your dependent images up-to-date:

  • Automated Builds let Docker Hub automatically build your Dockerfile each time you push changes to it.
  • Repository Links can ensure that your image is also rebuilt any time %%REPO%% is updated.

Running as an arbitrary user

See the "Running as an arbitrary user" section of the php image documentation.

When running WP-CLI via the cli variants of this image, it is important to note that they're based on Alpine, and have a default USER of Alpine's www-data, whose UID is 82 (compared to the Debian-based WordPress variants whose default effective UID is 33), so when running %%IMAGE%%:cli against an existing Debian-based WordPress install, something like --user 33:33 is likely going to be necessary. See docker-library/wordpress#256 for more discussion around this.